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Penelitian ini bertujuan untuk menguji dan memberikan bukti empiris tentang pengaruh penghindaran pajak dan karakteristik perusahaan terhadap relevansi nilai, serta peran corporate governance dalam mempengaruhi penghindaran pajak terhadap relevansi nilai. Pengujian ini dilakukan pada 142 perusahaan publik yang tecatat pada Bursa Efek Indonesia selama periode 2012-2014 dengan menggunakan teknik analisi Partial Least Square (PLS). Hasil penelitian menunjukkan bahwa penghindaran pajak berpengaruh positif terhadap relevansi nilai. Karakteristik perusahaan berpengaruh negatif terhadap relevansi nilai. Serta corporate governance secara signifikan mengurangi pengaruh penghindaran pajak terhadap relevansi nilai. Penelitian ini memberikan implikasi yang luas mengenai agency problem yang digambarkan melalui tindakan penghindaran pajak perusahaan, serta signalling theory yang digambarkan dengan peningkatan relevansi nilai perusahaan. Penelitian ini juga memberikan implikasi kepada manajemen sebagai pengelola perusahaan agar lebih transparan dalam menyediakan informasi perusahaan dan mengoptimalkan penerapan mekanisme corporate governance untuk dapat menyajikan informasi keuangan yang berkualitas. Investor dalam melakukan kebijakan investasi tidak hanya melihat kemampuan perusahaan dalam menghasilkan laba, namun juga harus mempertimbangan peran krusial good corporate governance sebagai mekanisme kontrol terhadap perilaku oportunistik manajer. Terakhir, penelitian ini dapat memberikan implikasi bagi pihak regulator, khususnya kantor pajak untuk membuat regulasi yang lebih relevan dalam fungsi pengawasan dan dalam memeriksa pajak perusahaan agar penerimaan negara yang bersumber dari pajak dapat dioptimalkan.

Abstract The diverse applications of magnetorheological elastomer (MRE) drive efforts to understand consistent performance and resistance to failure. Stress relaxation can lead to molecular chain deterioration, degradation in stiffness and rheological properties, and ultimately affect the life cycle of MRE. However, quantifying the energy and molecular dynamics during stress relaxation is challenging due to the difficulty of obtaining atomic-level insights experimentally. This study employs molecular dynamics (MD) simulation to elucidate the stress relaxation in MRE during constant strain. Magnetorheological elastomer models incorporating silicone rubber filled with varying magnetic iron particles (50–80 wt%) were constructed. Experimental results from an oscillatory shear rheometer showed the linear viscoelastic region of MRE to be within 0.001–0.01% strain. The simulation results indicated that stress relaxation has occurred, with stored energies decreased by 8.63–52.7% in all MRE models. Monitoring changes in energy components, the highest final stored energy (12,045 kJ) of the MRE model with 80 wt% Fe particles was primarily attributed to stronger intramolecular and intermolecular interactions, revealed by higher potential energy (3262 kJ) and van der Waals energy (− 2717.29 kJ). Stress relaxation also altered the molecular dynamics of this MRE model as evidenced by a decrease in kinetic energy (9362 kJ) and mean square displacement value (20,318 Å2). The MD simulation provides a promising quantitative tool for elucidating stress relaxation, preventing material failure and offering insights for the design of MRE in the nanotechnology industry.

This study aims to determine the effectiveness of the Flipped-Project-based Learning model on student learning outcomes. This type of quasi-experimental research uses a control group pretest-posttest design that is applied to class XI IPS SMA Negeri 8 Malang, Indonesia (social sciences program at State Senior High School) academic years 2023-2024. The instrument used is an essay test of 5 questions on International Economic Cooperation material that has been tested for validity and reliability. Data analysis used tests of normality, homogeneity, and independent sample t-test. The result of the study showed that the Flipped-Project Based Learning model was effective in improving students' student learning outcomes in Economics Lessons. Recommendations for further research, it is necessary to develop a project-based model in a blended or hybrid model by utilising digital learning or e-learning platforms.

Silicone rubber magnetorheological elastomers (SR-MREs) are increasingly recognized for their resilience in marine conditions, offering prolonged service life and durability. This study evaluates the one-month durability of silicone rubber magnetorheological elastomers (SR-MREs) under seawater conditions. Results revealed a 6% reduction in hardness and an 8% decrease in Young’s modulus compared to unimmersed samples. Morphological and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) analyses supported these findings, revealing surface defects and chemical bonding changes. The immersed SR-MRE displayed a notable 250% increase in elongation at break, highlighting enhanced elasticity. Rheological properties revealed complex mechanical behavior, with an initial increase in storage modulus from 0.25 to 0.38 MPa in the presence of a magnetic field, followed by a gradual decrease to 0.15 MPa at 0 A and 0.52 Mpa at 5 A with strain. Additionally, this study proposes an illustrative mechanism to elucidate the relationship between seawater elements and SR-MRE behavior, enhancing our understanding of its mechanical properties and degradation in marine environments, thus highlighting SR-MRE’s potential as a durable material compared to traditional rubber composites.

The study aimed to describe the impact of Fiqh learning actions using the Make-a-Match method on the cooperative skills of eleventh-grade students at Madrasah Aliyah Muhammadiyah 1 Kota Malang. This research used a qualitative approach with class action research (CAR) designed with two cycles. The study subjects were students in the 11th grade of the Department of Social Sciences Education (IPS), which had 18 students. Researchers collected data through observations, interviews, and documentation during the class action process. They then analyzed it through the Miles, Huberman, and Saldana procedures. Research results showed that the Make-a-Match method improved students' collaborative skills. Each of the collaborative skills indicators showed an improvement from cycle I to cycle II. The match-seeking technique required in applying this learning method instructed students to actively follow learning, be responsible as group members, interact, and collaborate.

Abstract It is well known in the field of materials science that a substance’s longevity is significantly influenced by its environment. Everything begins with the initial contact on a material’s surface. This influence will then deteriorate and have an extended negative impact on the strength of the material. In this study, the effect of natural weathering in tropical climates on magnetorheological elastomer (MRE) was investigated through microstructural evaluation to understand the aging behavior of the environmentally exposed MRE. To understand and elucidate the process, MREs made of silicone rubber and 70 wt% micron-sized carbonyl iron particles were prepared and exposed to the natural weathering of a tropical climate for 90 days. The MRE samples were then mechanically tensile tested, which revealed that Young’s modulus increased, while elongation at break decreased. Surface degradation due to weathering was suspected to be the primary cause of this condition. Using scanning electron microscopy (SEM), the degradation of MRE was investigated as a function of morphological evidence. Upon examination through SEM, it was noted that the weathering effects on the morphology of the exposed samples showed distinct characteristics on the degraded surfaces of the MRE, including numerous microvoids, cavities, and microcracks. While these features were not prominent for the MRE itself, they bear resemblance to the effects observed in similar materials like rubber and elastomer. An atomic force microscope (AFM) is used to investigate the surface topography and local degradation conditions. This observation revealed a distinctive degradation characteristic of the MRE in connection to natural weathering in tropical climates. The surface damage of the MRE samples became severe and inhomogeneous during the environmental aging process, and degradation began from the exposed MRE surface, causing the mechanical characteristics of the MRE to significantly change.

A study regarding the role of Muhammadiyah in the pillars of community empowerment and strengthening needs to be carried out, considering that this organization is the largest organization in Indonesia. This article aimed to analyze the strength of Muhammadiyah's existence which focuses on the pillars of empowerment and strengthening of society. This paper was prepared using library research methods. Data were analyzed using qualitative descriptive analysis. Data visualization, especially regarding references and keywords that frequently appear, is assisted with VOSviewer. The results show that Muhammadiyah is an Islamic organization that has a clear and real role in empowering and strengthening of society. Muhammadiyah has a central role in the field of philanthropy, in fact this has become Muhammadiyah's identity. Al-Ma'un became the ideological-theological foundation of Muhammadiyah's struggle. The advocacy movement through community empowerment has changed the face of Muhammadiyah to become more populist. Community empowerment is carried out through action programs that directly touch on the real problems of poor and marginalized communities represented by farmers, fishermen, livestock breeders, workers, urban poor communities and people with disabilities. Women's groups who have been marginalized and tend to be subordinated have also become targets of empowerment work carried out by Muhammadiyah, especially through its wing organization, namely Aisyiyah.

Globally, scale deposition in water supply pipelines is one of the major problems faced by water utilities. This research aimed to determine the causes and effects of scale deposition in the water supply pipelines in Surakarta City, Indonesia. The total dissolved solids (TDS), hardness, manganese, and alkalinity in groundwater were higher than those in the surface water and spring water; thus, the supply areas from groundwater were identified using TDS at the taps. The three scaling indicators, i.e., the Langelier saturation index (LSI), the Ryznar stability index (RSI), and the Puckorius scaling index (PSI), indicated moderate calcium carbonate scaling. However, elemental analysis of eight scale samples using X-ray fluorescence (XRF) revealed that the major components of scale were either manganese (50.1–80.8%) or iron (45.6–63.8%), whereas calcium (3.0–7.8%) was a minor component. Because only five of twenty groundwater sources were chlorinated before distribution, it is estimated that dissolved manganese is oxidized by manganese-oxidizing bacteria. The manganese deposition rate in the networks was estimated to be 1660 kg/year using the manganese concentration at groundwater sources and in customers’ taps. These results suggest the importance of the elemental analysis of scale and avoidance of overreliance on scale indicators.

Corrosion in carbon steel (CS) has been an existing issue and it calls attention to the need for improved corrosion protection. At present, superhydrophobic (SHB) coating technology has piqued the interest of researchers as alternative means of mitigating metal corrosion. Herein, a one-step solution deposition process was used to prepare an SHB coating based on nano-zinc oxide/epoxy (ZnO/EP) on CS and its corrosion resistance performance was analyzed by the means of electrochemical analysis and compared with that of the blank CS metal and the regular coatings (plain EP and regular ZnO/EP). Results implied the as-prepared SHB coating shows remarkable improvement in corrosion protection for the substrate. Notably, it exhibited higher in both impedance modulus (|Z|) and coating resistance (Rc) results approaching 1010 Ωcm2, than those of regular coatings by 3 orders of magnitude to that of plain EP (∼107 Ω cm2), and 1 order of magnitude to regular coating (∼109 Ω cm2), indicating its superior corrosion resistance performance. Besides that, the superior inhibitive effect of the SHB ZnO/EP (ZES) is also proven by the potentiodynamic polarization (PDP) results, in which the Icorr value is suppressed down to 2.08 × 10−11 A/cm2, thereby achieving an excellent corrosion rate result of 3.38 × 10−11 mm/year. The exceptional barrier protection is ascribed to the presence of a stabilized air interlayer captured within the coating/electrolyte interface thus effectively blocking the penetration of electrolyte into the coating. This facile yet effective one-step processed SHB coating offers an effective route to improve the corrosion resistance performance of the CS metal and thereafter expand its potential applications.

Online food delivery services (OFDS) which are commonly endeavored by food delivery workers have become revolutionary today. However, the alarming rates of road accidents among them resulted in the announcement of obligatory contributions towards the Social Security Protection scheme in Malaysia, starting 1st October 2021. The Self-Employment Social Security Scheme was introduced to provide protection for individuals who are selfemployed under the provisions of the Self-Employment Social Security Act 2017. A survey was conducted among 50 food delivery riders around Kuala Lumpur and Selangor on awareness of the scheme, exploring delivery rider demographic characteristics, awareness on benefits of the protection scheme, importance, or willingness to commit with the contribution towards social security protection, along with issues of concern during work. The analysis showed that the riders realize the importance and benefits of the Social Security Protection scheme and are willing to commit to it. Various underlying issues on egregious riding act to ensure fast delivery were also elaborated. In conclusion, the above findings provide evidence that food delivery riders understand that positioning them under the self-employment security scheme could provide protection against employment injuries including occupational diseases and accidents during work-related activities. Potential measures for a sound working environment and alleviate risky practices are also discussed.

Road accidents occurred everywhere along the expressway, especially at the inter-urban expressway, due to its high accessibility to wide-ranging highway networks. This study uses dataset from Shah Alam Expressway from 2013 to 2017 to determine the pattern of road accidents which includes the identification of high-risk locations at the expressway as well as the attributes to the accidents at those locations. In order to determine the high-risk location, the weightage point method and accident crash frequency method have been adopted. From the two methods applied, three popular identical sites have been identified as high-risk locations at both the westbound and eastbound. For the west bound, segments 19, 46 and 63 are considered as high risk whereas for the east bound, the high-risk locations are at segments 19, 46 and 60. Most of the accidents at the high-risk locations for west and east bounds caused no injury to road users and happened during daytime. Appropriate countermeasures should be done by local authorities in order to reduce accidents at the above-mentioned area. However, special countermeasures should be considered for segments 8, 28, 31 and 32 at the west bound whereby road accidents frequently happened during nighttime at these locations. On the other hand, a special scheme and countermeasure can be implemented for segment 46 at the eastbound where motorcyclists played a major involvement in road accidents at this location. Future research may consider applying some spatial statistics for detailed analysis to the accident dataset.

Abstract This paper aims to investigate the mechanical and rheological properties of magnetorheological elastomer (MRE) in marine ecosystems. The prepared samples comprised silicone rubber (SR) and 70 wt% micron-sized carbonyl iron particles (CIPs), immersed in an artificial marine ecosystem using salt water (Natrium Chloride) for 30 days. The mechanical properties of MRE samples were evaluated using hardness and quasi-static tensile tests. While the rheometer was used to investigate the rheological properties of their storage modulus condition with magnetic field stimulation. Further analysis of the defects and damages caused by salt water ageing was done through morphological observation using scanning electron microscope (SEM) technology. The results showed that the hardness and tensile strength of MRE samples that were soaked in salt water were affected over time. Lower values of hardness and tensile strength were obtained after 30 days due to the presence of Na+ and Cl−, which acted as an accelerator to the hydrolyzation process of the MRE. The process then, enhanced the water ingress capability into the matrix to cause the molecular changes. Interestingly, for rheological properties, 30 days of salt water ageing allowed the water molecules to move the MRE matrix molecular chains apart, a process known as plasticization and thus increasing the MR effect. Furthermore, morphological evidence was established to determine the MRE changes during salt water ageing. The research findings should greatly contribute to a better understanding of the effect of salt water on the performance of MRE.

Benign renal lesions are relatively rare. Angiomyolipoma (AML) is the most commonly encountered benign renal lesion. One of the complications of AML is rupture, which results in retroperitoneal haemorrhage with a mortality rate of up to 20%. Pregnancy poses a major risk for the rupture of AML. This is attributed to its hormonal effect, which causes the tumour to grow rapidly during pregnancy. The possibility of AML rupture should be considered when encountering pregnant patients with hypovolemic shock but with normal initial obstetric ultrasound findings. We present a case of a pregnant patient who was admitted with hypovolemic shock and CT scan confirmed rupture of AML.

The potential of magnetorheological (MR) foam, a recently developed porous smart material, has grown rapidly in recent years. The ability of MR foam to change its properties continuously, actively, and reversibly in response to a controlled external magnetic stimulus is one of its advantages for applications in advanced technology industries. However, its ability to store energy is still relatively low. This study attempts to address this drawback by highlighting a method to improve this ability by enhancing the material's storage modulus by introducing constrained foaming during the fabrication process. MR foam containing 75 wt% carbonyl iron particles (CIPs) was prepared in situ using two foaming approaches: free and constrained foaming. The effect of constraint foaming on the storage modulus enhancement was further investigated by reducing the mold length by 25 % and 50 %. The rheological properties of the fabricated MR foam samples were then examined using a rheometer in both the absence and presence of magnetic fields in an oscillatory shear mode. Thus, this study showed that constraint foaming has successfully improved the properties, especially regarding storage modulus and MR effect. When the mold volume was further reduced by 50 %, the storage modulus increased by about 50 % compared to a free-foaming MR foam at off-state conditions. Meanwhile, the results portrayed a higher storage modulus value under a 0.659 T magnetic field. This positive enhancement was believed to be due to a more compact CIP distribution. Hence, constraint volume MR foams were able to form stronger chain-like structures. The micrograph analysis by digital microscope revealed that the pore size decreased as the mold length was reduced. A shorter mold resulted in a more compact distribution of magnetic particles. As a result, MR foam with constrained foaming, especially at 50 % mold length, has a higher storage modulus. Overall, using constrained foaming to fabricate MR foam could improve the structure and mechanical properties of MR foam for a wide range of smart devices.

The ability of a vehicle to protect its occupants from serious injuries in the event of a collision is defined as crashworthiness. The proper design of lightweight energy absorption components is a topic of interest because it can enhance the occupant's safety and lead to less fuel consumption and gas emission. Honeycomb structures are known to have excellent mechanical performances, which are mainly due to the configurations of the unit cell. Thus, they have attracted attention in the field of automobiles, railway vehicles, etc. In the present work, the criteria of crashworthiness as well as the nature-bioinspired cellular structures are first introduced. Then, the various classifications of advanced honeycomb design, including graded, hierarchical, and sandwich panel-based honeycomb structures, are established and discussed with a focus on the advantageous effect of various designs on the crashworthiness of honeycomb-based structures. Finally, the importance of potential design to enhance the crashworthy performance of honeycomb structures together with the future challenges is summarized. This work provides a good understanding of architectural design for a new generation of advanced honeycomb-based structures with efficient energy-absorbing properties.

This study aim to seek the relationship between self-effort and e-learner success, either directly or through self-regulation. This type of research is quantitative. The research method used is an exploratory survey. Primary data were obtained from questionnaires filled out by 923 Social Science Education students at all State Islamic Universities in Indonesia. 11 State Islamic Universities with a Social Science Education program participated in this research. The direct test uses Ordinary Least Square (OLS), while the indirect effect is tested using the Sobel test. The results of this study can prove that self-effort has a direct and indirect positive influence on e-learner success through self-regulation. Students with high self-effort will be able to improve their self-regulation, impacting their e-learning success. This evidence shows that e-learning requires students' independence to succeed academically. This research provides a theoretical contribution to the development of e-learning theory. Students in online learning success need self-effort and self-regulation because, in online learning, students are required to be more active than in direct learning in class. The author recommends further research to expand other variables that affect the success of e-learning with different models and theories, such as expectation confirmatory theory, technology acceptance model, intention to continue using LMS, course and information quality.

The phenomenon of covid-19 has not been completed because the virus continues to mutate from the alpha, delta, gamma to Omicron variants, this variant is more virulent and quickly spreads than the previous variant. The impact is still being felt today. This study aims to investigate how SMEs can deal with crises and the strategies they have used to maintain their business, to prepare SMEs for future crises. The population in this study are SMEs who are members of the Institute for Modern Creative Industries (LIKM). The sampling technique used purposive sampling technique with 6 sources. This research is a type of qualitative research with a case study approach. The type of case study used is a collective or multiple case study. This study uses primary data. Data collection techniques used in this study were interviews and observation. The data analysis technique used is the spiral model technique. The results of this study, so that SMEs can survive the strategy used is to increase advertising and promotion through social media. Marketing using social media clearly has a very high effectiveness and contributes to sales volume. The marketing model found shows that the higher the understanding of business actors on the potential of digital marketing using social media, the more precise they will be in choosing a marketing model using social media

Abstract This study introduces a novel platform to predict complex modulus variables as a function of the applied magnetic field and other imperative variables using machine learning. The complex modulus prediction of magnetorheological (MR) elastomers is a challenging process, attributable to the material’s highly nonlinear nature. This problem becomes apparent when considering various possible fabrication parameters. Furthermore, traditional parametric modeling methods are limited when applied to solve larger-scale cases involving large databases. Consequently, the application of non-parametric modeling such as machine learning has gained increasing attraction in recent years. Therefore, this work proposes a data-driven approach for predicting multiple input-dependent complex moduli using feedforward neural networks. Besides excitation frequency and magnetic flux density as operating conditions, the inputs consider compositions and curing conditions represented by magnetic particle weight percentage and the curing magnetic field, respectively. Extreme learning machines and artificial neural networks were used to train the models. The simulation results obtained at various curing conditions and other inputs confirm that the predicted complex modulus has high accuracy with an R2 of about 0.997, as compared to the experimental results. Furthermore, the predicted complex modulus pattern and magnetorheological effect agree with the experimental data using both the learned and unlearned data.

Kelurahan Tunggulwulung merupakan salah daerah di Kecamatan Lowokwaru, Kota Malang yang memiliki potensi daerah berupa kesenian budaya tradisional. Hal ini dapat menjadikan Kelurahan Tunggulwulung sebagai daerah yang berpotensi untuk dikembangkan menjadi kampung wisata budaya di Kota Malang. Perlu adanya pemberdayaan masyarakat Tunggulwulung melalui pelatihan tembang macapat. Melalui program kegiatan pengabdian masyarakat di Universitas Islam Negeri Maulana Malik Ibrahim Malang, diharapkan menjadi salah satu program yang tepat dalam membantu masyarakat Tunggulwulung meningkatkan potensi daerah sebagai Kampung Budaya Tunggulwulung Yang Berbhineka Tunggal Ika yang dikenal masyarakat luas, baik nasional maupun internasional. Kegiatan pengabdian masyarakat ini bertujuan untuk: (1) mengetahui perencanaan pelatihan tembang macapat; (2) terealisasikan pelaksanaan kegiatan pelatihan tembang macapat; (3) menumbuhkan kesadaran dari hasil kegiatan pelatihan tembang macapat; dan (4) mengetahui hambatan-hambatan kegiatan pelatihan tembang macapat. Penelitian ini menggunakan metode Partisipatory Action Research (PAR) dengan tahapan: Plan (Perencanaan), Action (Tindakan), Observe (Pengamatan), dan Reflect (Refleksi). Hasil pengabdian berbasis riset ini, yaitu (1) penyusunan materi kegiatan pelatihan tembang macapat pada tahap perencanaan; (2) pelaksanaan latihan tembang macapat bertempat di Sekolah Budaya Tunggulwulung; (3) kegiatan pelatihan ini dapat memberikan kontribusi terhadap Kelurahan Tunggulwulung dalam mendukung terciptanya kampung budaya; dan (4) hambatan pada pelatihan tembang macapat: a) sulit menemukan waktu dalam latihan,b) peserta pelatihan dari kalangan tertentu saja, dan c) warga Kelurahan Tunggulwulung tidak semua warga berasal dari Jawa, sehingga enggan mengikuti pelatihan. Tembang Macapat: Motivator of Tunggulwulung Village Towards the Malang City Cultural Tourism Village ABSTRACT Tunggulwulung Village is one of the areas in Lowokwaru District, Malang City which has regional potential in the form of traditional cultural arts. This can make Tunggulwulung Village an area that has the potential to be developed into a cultural tourism village in Malang. The need for community empowerment in Tunggulwulung through macapat song training. Through the community service program at the State Islamic University of Maulana Malik Ibrahim Malang, it is expected to be one of the right programs to help the people of Tunggulwulung improve the potential of the region as the Diverse Single Cultural Community of Tunggulwulung, known to the wider community, both nationally and internationally. This community service activity aims to: (1) know the planning of a macapat song training; (2) the implementation of macapat song training activities is realized; (3) raising awareness of the results of macapat song training activities; and (4) know the obstacles of macapat song training activities. This research uses the Participatory Action Research (PAR) method with stages: Plan, Action, Observe, and Reflect. The results of this research-based service, namely (1) the preparation of material for macapat song training activities at the planning stage; (2) the macapat song training exercise takes place at the Tunggulwulung Cultural School; (3) this training activity can contribute to the Tunggulwulung Village in supporting the creation of a cultural village; and (4) barriers to macapat song training: a) it is difficult to find time in training, b) only certain participants, and c) not all residents of Tunggulwulung Kelurahan are from Java, so they are reluctant to attend training. Keywords: macapat song; Tunggulwulung Village; village of cultural tourism

Magnetorheological (MR) foam is a newly developed porous smart material that is able to change its properties continuously, actively, and reversibly in response to controllable external magnetic stimuli. Unfortunately, the stiffness or also known as storage modulus of MR foam is still rather low and insufficient, in the range of below 100 kPa only, due to weak interparticle interaction between CIPs and the foam matrix, which consequently restricts the potential of MR foam to be used in future sensor applications or in other semi-active devices. Therefore, the aim of this research is to enhance the structural and storage modulus of MR foam by adding silica nanoparticles as an additive. Consequently, MR foam samples with different compositions of silica nanoparticles in the range of 0–5 wt% were prepared via an in situ method. The rheological properties were tested under an oscillatory shear mode with the absence and presence of magnetic fields using a rheometer, with the input parameters of strains between 0.001% and 10% and range of magnetic flux density between 0 and 0.73 T for a magnetic field sweep test. The rheological findings show that with the addition of silica nanoparticles, particularly at 4 wt%, have enhanced the storage modulus of MR foam by 260%, which attributed to the highest stiffness from 45 to 162 kPa. Meanwhile, the change of storage modulus under the influence of magnetic fields (0 T–0.73 T) somehow showed small increment, about ∆1 kPa for each concentration of silica nanoparticles in MR foams, due to non-magnetic behavior of silica. The morphological characteristics of MR foams were described by an elemental analysis carried out by a using variable pressure scanning electron microscope (VPSEM) equipped with energy dispersive x-ray spectroscopy (EDX). The micrographs demonstrated large open-cell pores for MR foam, while MR foam with silica nanoparticles exhibited more closed-cell pores, associated with the enhancement of its storage modulus. It indicates that the silica nanoparticles have encouraged well dispersion of the particles in the foam matrix, which improved and strengthened the microstructure of MR foams through formation of silane coupling bonds of silica in the filler-matrix structure. Overall, incorporation of silica nanoparticles as an additive in the MR foam could provide advantage in enhancing the structure and mechanical properties of MR foam, for various future smart devices.

Abstract The widespread use of magnetorheological elastomer (MRE) materials in various applications has yet to be limited due to the fact that there are substantial deficiencies in current experimental and theoretical research on its microstructural durability behavior. In this study, MRE composed of silicon rubber (SR) and 70 wt% of micron-sized carbonyl iron particles (CIP) was prepared and subjected to stress relaxation evaluation by torsional shear load. The microstructure and particle distribution of the obtained MRE was evaluated by a field emission scanning electron microscopy (FESEM). The influence of constant low strain at 0.01% is the continuing concern within the linear viscoelastic (LVE) region of MRE. Stress relaxation plays a significant role in the life cycle of MRE and revealed that storage modulus was reduced by 8.7%, normal force has weakened by 27%, and stress performance was reduced by 6.88% along approximately 84,000 s test duration time. This time scale was the longest ever reported being undertaken in the MRE stress relaxation study. Novel micro-mechanisms that responsible for the depleted performance of MRE was obtained by microstructurally observation using FESEM and in-phase mode of atomic force microscope (AFM). Attempts have been made to correlate strain localization produced by stress relaxation, with molecular deformation in MRE amorphous matrix. Exceptional attention was focused on the development of molecular slippage, disentanglement, microplasticity, microphase separation, and shear bands. The relation between these microstructural phenomena and the viscoelastic properties of MRE was diffusely defined and discussed. The presented MRE is homogeneous with uniform distribution of CIP. The most significant recent developments of systematic correlation between the effects of microstructural deformation and durability performance of MRE under stress relaxation has been observed and evaluated.

Magnetorheological elastomer (MRE), which is capable of exhibiting magnetostriction in the presence of a magnetic field, has a great potential to be used for the development of sensor devices. Unfortunately, to date, many works focused on studying low modulus of MRE (less than 100 kPa) which can hamper their potential application in sensors due to short lifespan and low durability. Thus, in this work, MRE with storage modulus above 300 kPa is to be developed to enhance magnetostriction magnitude and reaction force (normal force). To achieve this goal, MREs are prepared with various compositions of carbonyl iron particles (CIPs), in particular, MRE with 60, 70 and 80 wt.% of CIP. It is shown that both the magnetostriction percentage and normal force increment are achieved as the concentration of CIPs increases. The highest magnetostriction magnitude of 0.075% is obtained with 80 wt.% of CIP, and this increment is higher than that of moderate stiffness MRE developed in the previous works. Therefore, the midrange range modulus MRE developed in this work can copiously produce the required magnetostriction value and potentially be implemented for the design of forefront sensor technology.

Abstract Carbonyl iron particles (CIPs) is one of the key components in magnetic rubber, known as magnetorheological elastomer (MRE). Apart from the influence of their sizes and concentrations, the role of the particle’ shape is pronounced worthy of the attention for the MRE performance. However, the usage of CIPs in MRE during long-term applications may lead to corrosion effects on the embedded CIPs, which significantly affects the performance of devices or systems utilizing MRE. Hence, the distinctions between the two types of MRE embedded in different shapes of spherical and plate-like CIPs, at both conditions of non-corroded and corroded CIPs were investigated in terms of the field-dependent rheological properties of MRE. The plate-like shape was produced from spherical CIPs through a milling process using a rotary ball mill. Then, both shapes of CIPs individually subjected to an accelerated corrosion test in diluted hydrochloric (HCl) at different concentrations, particularly at 0.5, 1.0, and 1.5 vol.% for 30 min of immersion time. Eight samples of CIPs, including non-corroded for both CIPs shapes, were characterized in terms of a morphological study by field emission scanning electron microscope (FESEM) and magnetic properties via vibrating sample magnetometer (VSM). The field-dependent rheological properties of MREs were analyzed the change in the dynamic modulus behavior of MREs via rheometer. From the application perspective, this finding may be useful for the system to be considered that provide an idea to prolong the performance MRE by utilizing the different shapes of CIPs even when the material is fading.

This study proposes the design and fabrication of a natural rubber-based magnetorheological elastomer (NR-MRE) engine mount as a new device in absorbing the vibration originated from the automotive engine. The conceptual design was performed through a simulation process by Finite Element Method Magnetics to analyze the magnetic field distribution. The simulation result had indicated that the device was capable of generating an equivalent magnetic field density of 0.31 T at the effective area. The MRE was prepared by utilizing 60 wt% of carbonyl iron particles (CIPs), and the cavity was filled by compression molding. The MRE compound was tested based on its basic mechanical properties, while the MRE engine mounts were tested under a static compression load at off- and on-state conditions. It was observed that the compound possessed a good tensile strength for a load bearer matrix with an average of 12.65 MPa. Subsequently, the results of the static compression load had showed that the MRE engine mounts recorded an increase of 12% in the force generated as compared to conventional engine mounts at an off-state condition. Meanwhile, at an on-state condition of 2.4 A, the MRE engine mounts recorded an increase in the force generated with 106%. The study has demonstrated that the proposed device can be one of the potential candidates for vibration control applications due to its stiffness controllability.

This study aims to investigate an appropriate ankle velocity reference (ωref), which is the average ankle velocity of a certain healthy subject when walking with a certain walking speed. The goal is to improve a Passive Controllable Ankle Foot Orthosis (PICAFO) by implementing the ankle velocity reference. Firstly, the function to estimate ωref, based on walking speed and body mass index (BMI), is obtained from 16 able-bodied subjects walking gait data. The effect of controlled stiffness (based on wref) to the user's ankle kinematics and muscle activity was evaluated by comparing it to other settings, such as walking barefooted and various constant damping stiffness (0%, 30%, 60%, and 100% of the maximum damping stiffness). Two able-bodied subjects (normal and overweight) participated in the evaluation, where they had to walk at two different walking speeds (1 and 2 km/h). The result showed that ankle kinematics and muscle activity were improved when w was controlled during walking speed of 1 km/h for both subjects. In terms of ankle kinematics, the toe clearance occurred, and walking stability increased. In terms of muscle activity, the average muscle activity had reduced by ~29% for the normal subject and by ~57% for an overweight subject, which shows that PICAFO provides necessary damping stiffness to replace the muscle works partially. In the future, by using the ωref based on walking speed and BMI, the therapists can skip the trial and error process of finding an appropriate PICAFO prescription for a post-stroke patient.

Most parts of the failures in structural elements in use were consequences of mechanical durability. Therefore, durability had been one of the critical factors to be considered in designing durable mechanical elements. In magnetorheological elastomer (MRE) materials, the durability process involves different damage mechanisms that result in the degradation of the materials. Increasingly used of outstanding performance of MRE was susceptible to failure under durability performance for various applications. In response to these problems, with limited sources of published articles on MRE durability, an overview of the durability of elastomer based MRE is presented. The study focuses on collecting and analyzing the works including experimental and modeling approaches that have been conducted on MRE durability up to date. Two bibliographic searched databases, Scopus and Web of Science were consulted to collect the final set of articles with the aims to identify current and future trends of MRE durability. Prominence works conducted on MRE durability were also encapsulated in this paper to provide a visual perspective and subsequently motivate researchers to heighten the need for MRE durability investigation.

For the first time, the interfacial microstructures and hardening mechanisms of a multi-material (MM) 316L stainless steel/Inconel 718 (316L SS/IN 718) interface fabricated by a novel multi-material selective laser melting (MM SLM) additive manufacturing (AM) system have been investigated in this study. MM 316L SS/IN 718 parts were successfully built with high densification levels (>99%) and low porosity content (average: ~0.81%). Microscopy analysis indicates that the interfacial microstructures are characterised by dense dislocation tangling networks, NbC and TiC, and very small amounts of Laves phase (

ENHANCEMENT OF TEACHERS PROFESSIONALISM THROUGH SPARKOL VIDEOSCRIBE LEARNING MEDIA WORKSHOP IN MALANG DISTRICT. The program of activities proposed by the group of KKM 68 and 105 UIN Maulana Malik Ibrahim Malang, in the form of assistance in making sparkol videoscribe learning media. Through these activities, it is expected that the product of the development can add learning resources for teachers and students, and become an encouragement for students in learning. The method used in this service is service learning. Service learning is learning for students based on understanding and the process of recognizing a community. Community service activities in the form of ICT media development workshops can improve the understanding of elementary school teachers in Tulusbesar Village, Malang District in making and using learning media with sparkol videoscribe applications. The products produced in these activities are in the form of learning media in the form of sparkol videoscribe which are interesting in material grades 1 to 6 of elementary school. This service activity received a positive response from teachers as workshop participants.

The enhancement of fuel economy and the emission of greenhouse gases are the key growing challenges around the globe that drive automobile manufacturers to produce lightweight vehicles. Additionally, the reduction in the weight of the vehicle could contribute to its recyclability and performance (for example crashworthiness and impact resistance). One of the strategies is to develop high-performance lightweight materials by the replacement of conventional materials such as steel and cast iron with lightweight materials. The lightweight composite which is commonly referred to as fiber-reinforced plastics (FRP) composite is one of the lightweight materials to achieve fuel efficiency and the reduction of CO2 emission. However, the damage of FRP composite under impact loading is one of the critical factors which affects its structural application. The bumper beam plays a key role in bearing sudden impact during a collision. Polymer composite materials have been abundantly used in a variety of applications such as transportation industries. The main thrust of the present paper deals with the use of high-strength glass fibers as the reinforcing member in the polymer composite to develop a car bumper beam. The mechanical performance and manufacturing techniques are discussed. Based on the literature studies, glass fiber-reinforced composite (GRP) provides more promise in the automotive industry compared to conventional materials such as car bumper beams.

Strain localization is a significant issue that poses interesting research challenges in viscoelastic materials because it is difficult to accurately predict the damage evolution behavior. Over time, the damage mechanism in the amorphous structure of viscoelastic materials leads to subsequent localization into a shear band, gradually jeopardizing the materials’ elastic sustainability. The primary goal of this study is to further understand the morphological effects and the role of shear bands in viscoelastic materials precipitated by strain localization. The current study aims to consolidate the various failure mechanisms of a sample and its geometry (surface-to-volume ratio) used in torsional testing, as well as to understand their effects on stress relaxation durability performance. A torsional shear load stress relaxation durability test was performed within the elastic region on an isotropic viscoelastic sample made of silicon rubber and a 70% weight fraction of micron-sized carbonyl iron particles. Degradation was caused by a shear band of localized plasticity that developed microscopically due to stress relaxation durability. The failure pattern deteriorated as the surface-to-volume ratio decreased. A field-emission scanning electron microscope (FESEM) and a tapping-mode atomic force microscope (AFM) were used for further observation and investigation of the sample. After at least 7500 cycles of continuous shearing, the elastic sustainability of the viscoelastic materials microstructurally degraded, as indicated by a decline in stress performance over time. Factors influencing the formation of shear bands were observed in postmortem, which was affected by simple micromanipulation of the sample geometry, making it applicable for practical implementation to accommodate any desired performance and micromechanical design applications.

Magnetorheological elastomers (MREs) are well-known for their ability to self-adjust their mechanical properties in response to magnetic field influence. This ability, however, diminishes under high-strain conditions, a phenomenon known as the stress-softening effect. Similar phenomena have been observed in other filled elastomers; hence, the current study demonstrates the role of fillers in reducing the effect and thus maintaining performance. Anisotropic, silicone-based MREs with various carbonyl iron particle (CIP) concentrations were prepared and subjected to uniaxial tensile load to evaluate high-strain conditions with and without magnetic influence. The current study demonstrated that non-linear stress–strain behavior was observed in all types of samples, which supported the experimental findings. CIP concentration has a significant impact on the stress–strain behavior of MREs, with about 350% increased elastic modulus with increasing CIP content. Microstructural observations using field emission scanning electron microscopy (FESEM) yielded novel micro-mechanisms of the high-strain failure process of MREs. The magnetic force applied during tension loading was important in the behavior and characteristics of the MRE failure mechanism, and the discovery of microcracks and microplasticity, which was never reported in the MRE quasi-static tensile, received special attention in this study. The relationships between these microstructural phenomena, magnetic influence, and MRE mechanical properties were defined and discussed thoroughly. Overall, the process of microcracks and microplasticity in the MRE under tensile mode was primarily formed in the matrix, and the formation varies with CIP concentrations.

Filler additive is used to provide superior bonding in rubber matrix to enhance the storage modulus of magnetorheological elastomer (MRE). However, the magneto-induced modulus is reduced as the initial storage modulus increases. Therefore, this paper aims to increase the magneto-induced modulus and maintain the initial storage modulus by combining filler and plasticizer additives. Both types of additives have different functions, where cobalt ferrite (CoFe2O4) is capable of enhancing the maximum storage modulus and silicone oil (SO) reduces the initial storage modulus. Thus, four MRE samples have been fabricated using (a) no additive, (b) CoFe2O4, (c) SO, and (d) a combination of CoFe2O4 and SO. The sample’s hardness and magnetic properties were investigated via Durometer Shore A and Vibrating Sample Magnetometer (VSM), respectively. Furthermore, the rheological properties of MRE samples in terms of storage modulus were investigated upon the frequency and magnetic field sweep using a rheometer. The results demonstrated that the storage modulus of the MRE samples has increased with increasing the oscillation frequency from 0.1 to 50 Hz. Interestingly, the combination of additives has produced the largest value of magneto-induced modulus of 0.90 MPa as compared to other samples. Furthermore, their initial storage modulus was in between samples with SO (lowest) and without additive (highest). Therefore, fundamental knowledge in adding the combination of additives can offer solutions for a wide range of stiffness in MR device applications such as vibration and noise control devices, sensing devices, and actuators.

Magnetorheological elastomer (MRE) materials have the potential to be used in a wide range of applications that require long-term service in hostile environments. These widespread applications will result in the emergence of MRE-specific durability issues, where durability refers to performance under in-service environmental conditions. In response, the outdoor tropical climatic environment, combined with the effects of weathering, will be the primary focus of this paper, specifically the photodegradation of the MRE. In this study, MRE made of silicone rubber (SR) and 70 wt% micron-sized carbonyl iron particles (CIP) were prepared and subjected to mechanical and rheological testing to evaluate the effects under natural weathering. Magnetorheological elastomer samples were exposed to the natural weathering conditions of a tropical climate in Kuala Lumpur, Malaysia, for 30 days. To obtain a comprehensive view of MRE degradation during natural weathering, mechanical testing, rheology, and morphological evaluation were all performed. The mechanical and rheological properties test results revealed that after 30 days of exposure and known meteorological parameters, Young’s modulus and storage modulus increased, while elongation at break decreased. The degradation processes of MRE during weathering, which are responsible for their undesirable change, were given special attention. With the help of morphological evidence, the relationship between these phenomena and the viscoelastic properties of MRE was comprehensively defined and discussed.

This study aims to 1) explain the development products of Student Worksheet on Student's creative thinking Skill; 2) describe the validity product of student Worksheet on Student's creative thinking Skill; and 3) describe the influence of student worksheet on Student's creative thinking Skill. The method in this study used to research and development (RD) the model of R D in this study using Borg Gall. The analysis used in the study of development technique has three of them, a review of the learning contents, descriptive analysis, and the analysis of the test results. The development of learning materials in the form of student worksheet of creativity proved can improve the process creative thinking skill of grade V SDN Tambak Asri 02 Malang. Suggestions for optimizing the utilization of materials development is 1) the development of learning materials can utilized as references for educators. 2) Learning materials that have been developed this for more good news can be integrated with the Quran or the Hadith perspective.

This study aims at determining the effectiveness of the distribution and use of the Village Funds and their impacts on the increase in capital accumulation in Bondowoso Regency. This research is a quantitative research with a confirmatory approach because the researchers confirm the relationship between the research variables and test the hypotheses previously formulated. The analytical tool used is Structural Equity Modeling with the help of Lisrel 8.8 software. Respondents in this research amount to 75 villages in Bondowoso Regency that are selected based on purposive sampling (to select the subdistricts) and simple random sampling (to select villages/respondents). The results of research state that the effectiveness of the use of village funds has a significant influence on capital accumulation and empowerment of rural communities in Bondowoso Regency. Whereas capital accumulation has no significant influence on the empowerment of rural communities in Bondowoso Regency.

This paper investigated the rheological properties of a novel magnetorheological elastomer (MRE) with plate-like carbonyl iron particles (CIPs) as magnetic particles. MRE samples with different shape of CIPs; plate-like (MRE-P) and spherical-like (MRE-S), were prepared. The current work further highlights the effects of varying curing magnetic field towards the rheological properties. X-ray diffraction and magnetic properties analysis were carried out to observe not only the surface morphology of the CIPs but also the cross-section of CIPs in the MRE samples. Rheological properties such as strain amplitude, frequency, and magnetic field sweep test were measured using a rotational rheometer. The MRE-P samples demonstrated higher storage modulus and the loss factor lower than MRE-S. Besides that, the MR effect of MRE-P samples is slightly lower than that of MRE-S correspond to 114% and 137%, respectively.

Recently, magnetorheological grease (MRG) has been utilized in magnetorheological (MR) brakes to generate a braking torque based on the current applied. However, the high initial viscosity of MRG has increased the off-state torque that led to the viscous drag of the brake. Therefore, in this study, the off-state viscosity of MRG can be reduced by the introduction of dilution oil as an additive. Three samples consist of pure MRG (MRG 1) and MRG with different types of dilution oil; hydraulic (MRG 2) and kerosene (MRG 3) were prepared by mixing grease and spherical carbonyl iron particles (CIP) using a mechanical stirrer. The rheological properties in the rotational mode were examined using a rheometer and the torque performances in MR brake were evaluated by changing the current of 0 A, 0.4 A, 0.8 A, and 1.2 A with fixed angular speed. The result shows that MRG 3 has the lowest viscosity which is almost 93% reduction while the viscosity of MRG 2 has lowered to 25%. However, the torque performances generated by MRG 3 were highest, 1.44 Nm, when 1.2 A of current was applied and followed by MRG 2 and MRG 1. This phenomenon indicated that the improvement of torque performances was dependent on the viscosity of MRG. By reducing the viscosity of MRG, the restriction on CIP to form chain formation has also decreased and strengthen the torque of MRG brake. Consequently, the utilization of dilution oil in MRG could be considered in MR brake in near future.

Magnetorheological elastomer (MRE) consists of magnetic particles known as carbonyl iron (CIPs), which have been locked in a silicone-based matrix, in various alignments. However, current MRE exhibits inadequate rheological properties due to several issues such as particle alignments. Therefore, in this study, a new approach of the particle alignment of CIPs in MRE, namely fountain-like structure, is introduced. It is expected that this kind of MRE exhibits enhancement rheological responses, in off- and on-state conditions. This work includes the development of a new mold that can produce various directions of magnetic flux lines in order to have fountain-like structures of CIPs in MRE, during the curing process. Three types of particle alignments in MRE, namely isotropic, fountain-like and inverted fountain-like, are fabricated. The rheological properties of MRE in terms of storage modulus and MR effect are measured in an oscillatory shear mode using a rheometer. The results have revealed that fountain-like MRE exhibits higher storage modulus than the isotropic MRE, approximately 0.6 MPa of increment in the strain sweep test, in an on-state condition. Furthermore, it has been demonstrated from strain, frequency and the current sweep test that the rheological properties of fountain-like MRE related to storage modulus and magnetorheological (MR) effect are higher compared to the inverted fountain-like MRE.

Temperature is one of the most influential factors affecting the performance of elastomer matrix in magnetorheological elastomer (MRE). Previous studies have utilized silica as a reinforcing filler in polymer composite and as a coating material in MRE to improve the thermal stability of the base material. However, the usage of silica as an additive in the thermal stability of MRE has not been explored. Thus, in this study, the effect of silica as an additive on the temperature-dependent mechanical and rheological properties of ethylene propylene diene monomer (EPDM)-based MREs was investigated by using 30 wt.% carbonyl iron particles (CIPs) as the main filler, with different contents of silica nanoparticles (0 to 11 wt.%). The microstructure analysis was examined by using field-emission scanning electron microscopy (FESEM), while the thermal characterizations were studied by using a thermogravimetric analyzer and differential scanning calorimetry. The tensile properties were conducted by using Instron Universal Testing Machine in the absence of magnetic field at various temperatures. Meanwhile, the rheological properties were analyzed under oscillatory loadings in the influence of magnetic field, using a rotational rheometer at 25 to 65 °C. The results revealed that the temperature has diminished the interfacial interactions between filler and matrix, thus affecting the properties of MRE, where the tensile properties and MR effect decrease with increasing temperature. However, the presence of silica capable improved the thermal stability of EPDM-based MRE by enhancing the interactions between filler and matrix, thus reducing the interfacial defects when under the influence of temperature. Consequently, the incorporation of silica nanoparticles as an additive in EPDM-based MRE requires more exploration, since it has the potential to sustain the properties of MRE devices in a variety of temperature conditions. Thus, the study on the temperature-dependent mechanical and rheological properties of MRE is necessary, particularly regarding its practical applications.

Common sensors in many applications are in the form of rigid devices that can react according to external stimuli. However, a magnetorheological plastomer (MRP) can offer a new type of sensing capability, as it is flexible in shape, soft, and responsive to an external magnetic field. In this study, graphite (Gr) particles are introduced into an MRP as an additive, to investigate the advantages of its electrical properties in MRPs, such as conductivity, which is absolutely required in a potential sensor. As a first step to achieve this, MRP samples containing carbonyl iron particles (CIPs) and various amounts of of Gr, from 0 to 10 wt.%, are prepared, and their magnetic-field-dependent electrical properties are experimentally evaluated. After the morphological aspect of Gr–MRP is characterized using environmental scanning electron microscopy (ESEM), the magnetic properties of MRP and Gr–MRP are evaluated via a vibrating sample magnetometer (VSM). The resistivities of the Gr–MRP samples are then tested under various applied magnetic flux densities, showing that the resistivity of Gr–MRP decreases with increasing of Gr content up to 10 wt.%. In addition, the electrical conductivity is tested using a test rig, showing that the conductivity increases as the amount of Gr additive increases, up to 10 wt.%. The conductivity of 10 wt.% Gr–MRP is found to be highest, at 178.06% higher than the Gr–MRP with 6 wt.%, for a magnetic flux density of 400 mT. It is observed that with the addition of Gr, the conductivity properties are improved with increases in the magnetic flux density, which could contribute to the potential usefulness of these materials as sensing detection devices.

This paper investigated the effects of petroleum-based oils (PBOs) as a dispersing aid on the physicochemical characteristics of natural rubber (NR)-based magnetorheological elastomers (MREs). The addition of PBOs was expected to overcome the low performance of magnetorheological (MR) elastomers due to their inhomogeneous dispersion and the mobility of magnetic particles within the elastomer matrix. The NR-based MREs were firstly fabricated by mixing the NR compounds homogeneously with different ratios of naphthenic oil (NO), light mineral oil (LMO), and paraffin oil (PO) to aromatic oil (AO), with weight percentage ratios of 100:0, 70:30, 50:50, and 30:70, respectively. From the obtained results, the ratios of NO mixed with low amounts of AO improved the material physicochemical characteristics, such as thermal properties. Meanwhile, LMO mixed the AO led to the best results for curing characteristics, microstructure observation, and magnetic properties of the MREs. We found that the LMO mixed with a high content of AO could provide good compatibility between the rubber molecular and magnetic particles due to similar chemical structures, which apparently enhance the physicochemical characteristics of MREs. In conclusion, the 30:70 ratio of LMO:AO is considered the preferable dispersing aid for MREs due to structural compounds present in the oil that enhance the physicochemical characteristics of the NR-based MREs.

Polyvinyl alcohol (PVA)-based magnetorheological plastomer (MRP) possesses excellent magnetically dependent mechanical properties such as the magnetorheological effect (MR effect) when exposed to an external magnetic field. PVA-based MRP also shows a shear stiffening (ST) effect, which is very beneficial in fabricating pressure sensor. Thus, it can automatically respond to external stimuli such as shear force without the magnetic field. The dual properties of PVA-based MRP mainly on the ST and MR effect are rarely reported. Therefore, this work empirically investigates the dual properties of this smart material under the influence of different solvent compositions (20:80, 40:60, 60:40, and 80:20) by varying the ratios of binary solvent mixture (dimethyl sulfoxide (DMSO) to water). Upon applying a shear stress with excitation frequencies from 0.01 to 10 Hz, the storage modulus (G′) for PVA-based MRP with DMSO to water ratio of 20:40 increases from 6.62 × 10−5 to 0.035 MPa. This result demonstrates an excellent ST effect with the relative shear stiffening effect (RSTE) up to 52,827%. In addition, both the ST and MR effect show a downward trend with increasing DMSO content to water. Notably, the physical state of hydrogel MRP could be changed with different solvent ratios either in the liquid-like or solid-like state. On the other hand, a transient stepwise experiment showed that the solvent’s composition had a positive effect on the arrangement of CIPs within the matrix as a function of the external magnetic field. Therefore, the solvent ratio (DMSO/water) can influence both ST and MR effects of hydrogel MRP, which need to be emphasized in the fabrication of hydrogel MRP for appropriate applications primarily with soft sensors and actuators for dynamic motion control.

Magnetorheological elastomers (MRE)-based products are usually located in an area directly exposed to sunlight and rain. However, there is no specific research on the behavior of MRE after accelerated weathering. Therefore, in this study, the changes to the chemical and rheological properties of both isotropic and anisotropic MRE after accelerated weathering were examined. Treated and untreated specimens were compared. MRE specimens with 40% by weight CIP were prepared with no current excitation and another sample was prepared with 1.5 T of magnetic flux density. Each specimen was treated in an accelerated weathering machine, Q-Sun Xe-1 Xenon Test Chamber, under a UV light exposure cycle and water spray. A material characterization was carried out using FTIR and a rheometer to determine the changes to the chemical and rheological properties. The morphological analysis results showed that after the weather treatment, the surface was rough and more cavities occurred. The rheometer test results showed a significant decrease in the storage modulus of each treated MRE specimen, unlike the untreated MRE specimens. The decrease in the storage modulus value with currents of 0, 1, 2, and 3 Amperes was 66.67%, 78.9%, 85.2%, and 80.5%, respectively. Meanwhile, FTIR testing showed a change in the wave peak between the untreated and treated MRE specimens. Thermogravimetric analysis (TGA) also showed a decrease in MRE weight for each specimen. However, for both treated and untreated MRE specimens, the decrease in TGA was not significantly different. In all the tests carried out on the MRE samples, weather acceleration treatment caused significant changes. This is an important consideration for developers who choose silicone as the MRE matrix.

The use of highly viscous grease as a medium in magnetorheological grease (MRG) provides the benefit of avoiding sedimentation from occurring. However, it limits the expansion of yield stress in the on-state condition, thus reducing the application performance during operation. Therefore, in this study, the improvement in the rheological properties of MRG was investigated through the introduction of graphite as an additive. MRG with 10 wt % graphite (GMRG) was fabricated, and its properties were compared to a reference MRG sample. The microstructure of GMRG was characterized using an environmental scanning electron microscope (ESEM). The rheological properties of both samples, including apparent viscosity, yield stress, and viscoelasticity, were examined using a shear rheometer in rotational and oscillatory modes. The results demonstrated a slight increase in the apparent viscosity in GMRG and a significant improvement in yield stress by 38.8% at 3 A with growth about 32.7% higher compared to MRG from 0 to 3 A. An expansion of the linear viscoelastic region (LVE) from 0.01% to 0.1% was observed for the GMRG, credited to the domination of the elastic properties on the sample. These obtained results were confirmed based on ESEM, which described the contribution of graphite to constructing a more stable chain structure in the GMRG. In conclusion, the findings highlight the influence of the addition of graphite on improving the rheological properties of MRG. Hence, the addition of graphite in MRG shows the potential to be applied in many applications in the near future.

In this study, magnetorheological elastomer (MRE) was fabricated using an electromagnetic device with a new configuration mold at the orientation of 0°, 45° and 90°. This new curing concept enhanced the alignment of carbonyl iron particles (CIPs) within the silicone matrix in the presence of silicone oil (SO) during solidifying, by eliminating air gaps to prevent magnetic flux losses. Using a mold made of steel, which is a magnetic material, the mold functions as a guide for concentrated magnetic flux of 0.315 T to pass through the MRE sample. Scanning electron microscopy (SEM) was used to observe the surface morphology of the fabricated MRE samples particularly the alignment of the CIPs. The field-dependent dynamic properties of the MREs were measured using a rheometer. The analysis implied that the effectiveness of the MRE operating under shear deformation with this curing concept provided the highest magneto-induced modulus of 1.01 MPa when a 45° orientation mold is used, with relative magnetorheological (MR) effect value up to 918%, followed by 0° mold orientation with 0.79 MPa magneto-induced modulus and 646% relative MR effect. The high modulus properties offered by this MRE are believed to be potentially useful in industrial applications where a high range of stiffness is required particularly in the shear direction.

Micro mechanism consideration is critical for gaining a thorough understanding of amorphous shear band behavior in magnetorheological (MR) solids, particularly those with viscoelastic matrices. Heretofore, the characteristics of shear bands in terms of formation, physical evolution, and response to stress distribution at the localized region have gone largely unnoticed and unexplored. Notwithstanding these limitations, atomic force microscopy (AFM) has been used to explore the nature of shear band deformation in MR materials during stress relaxation. Stress relaxation at a constant low strain of 0.01% and an oscillatory shear of defined test duration played a major role in the creation of the shear band. In this analysis, the localized area of the study defined shear bands as varying in size and dominantly deformed in the matrix with no evidence of inhibition by embedded carbonyl iron particles (CIPs). The association between the shear band and the adjacent zone was further studied using in-phase imaging of AFM tapping mode and demonstrated the presence of localized affected zone around the shear band. Taken together, the results provide important insights into the proposed shear band deformation zone (SBDZ). This study sheds a contemporary light on the contentious issue of amorphous shear band deformation behavior and makes several contributions to the current literature.

This paper presents the effect of the micro-sized particles on the storage modulus and durability characteristics of magnetorheological elastomers (MREs). The initial phase of the investigation is to determine any associations among the microparticles’ weight percent fraction (wt%), structure arrangement, and the storage modulus of MRE samples. In order to carry out this, both isotropic and anisotropic types of MRE samples consisting of the silicone rubber matrix and 50, 60, 70, 75, and 80 wt% microparticles of carbonyl iron fractions are prepared. It is identified from the magneto-rheometer that the increase in storage modulus and decrease in linear viscoelastic region limit are observed in varying consistency depending on wt% and particle arrangement. The consistency of this dependency feature is highlighted by superimposing all of the graphs plotted to create the proposed the samples’ behavior model. In response to increasing magnetic stimulation, a sample of 70 wt% microparticles with an isotropic arrangement is found to be significant and stable. The experimentally defined fraction is then used for the durability test as the second phase of the investigation. During this phase, the durability evaluation is subjected to stress relaxation for an extended period of time. After undergoing durability testing, storage modulus performance is decreased by 0.7–13% at various magnetic stimulation levels. This result directly indicates that the storage modulus characteristics of different forms of MRE are sensitive to the different iron particle fractions’ and microparticles’ alignment. Therefore, important treatments to alter the storage modulus can be undertaken before the practical implementation to accommodate any desired performance of MRE itself and MRE application systems.

Polymer composites have been widely used as damping materials in various applications due to the ability of reducing the vibrations. However, the environmental and surrounding thermal exposure towards polymer composites have affected their mechanical properties and lifecycle. Therefore, this paper presents the effect of material-temperature dependence on the loss factor and phase shift angle characteristics. Two types of unageing and aging silicone-rubber-based magnetorheological elastomer (SR-MRE) with different concentrations of carbonyl iron particles (CIPs), 30 and 60 wt%, are utilized in this study. The morphological, magnetic, and rheological properties related to the loss factor and phase shift angle are characterized using a low-vacuum scanning electron microscopy, and vibrating sample magnetometer and rheometer, respectively. The morphological analysis of SR-MRE consisting of 30 wt% CIPs revealed a smoother surface area when compared to 60 wt% CIPs after thermal aging due to the improvement of CIPs dispersion in the presence of heat. Nevertheless, the rheological analysis demonstrated inimitable rheological properties due to different in-rubber structures, shear deformation condition, as well as the influence of magnetic field. No significant changes of loss factor occurred at a low CIPs concentration, whilst the loss factor increased at a higher CIPs concentration. On that basis, it has been determined that the proposed changes of the polymer chain network due to the long-term temperature exposure of different concentrations of CIPs might explain the unique rheological properties of the unaged and aged SR-MRE.

This study investigated the effect of adding strontium (Sr)-doped cobalt ferrite (CoFe2O4) nanoparticles in carbonyl iron particle (CIP)-based magnetorheological fluids (MRFs). Sr-CoFe2O4 nanoparticles were fabricated at different particle sizes using co-precipitation at calcination temperatures of 300 and 400 °C. Field emission scanning electron microscopy (FESEM) was used to evaluate the morphology of the Sr-CoFe2O4 nanoparticles, which were found to be spherical. The average grain sizes were 71–91 nm and 118–157 nm for nanoparticles that had been calcinated at 300 and 400 °C, respectively. As such, higher calcination temperatures were found to produce larger-sized Sr-CoFe2O4 nanoparticles. To investigate the rheological effects that Sr-CoFe2O4 nanoparticles have on CIP-based MRF, three MRF samples were prepared: (1) CIP-based MRF without nanoparticle additives (CIP-based MRF), (2) CIP-based MRF with Sr-CoFe2O4 nanoparticles calcinated at 300 °C (MRF CIP+Sr-CoFe2O4-T300), and (3) CIP-based MRF with Sr-CoFe2O4 nanoparticles calcinated at 400 °C (MRF CIP+Sr-CoFe2O4-T400). The rheological properties of these MRF samples were then observed at room temperature using a rheometer with a parallel plate at a gap of 1 mm. Dispersion stability tests were also performed to determine the sedimentation ratio of the three CIP-based MRF samples.