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The blasting method involving the placement of a cushion at the bottom of blast holes has found widespread application in the construction of foundations for hydraulic and hydroelectric projects. This study employs comprehensive techniques including CT scanning, three dimensional reconstruction, fractal damage theory, and digital image correlation methods. It conducts both three-dimensional and two dimensional blasting model experiments using foam, fine sand, and fine sand combined with steel balls as the bottom cushion medium. Comparative analysis is performed on the damage characteristics and strain evolution of the rock mass subjected to bottom cushion blasting. The results indicate that specimens with foam as the cushion medium at the bottom of the blast hole exhibit the highest degree of damage and strain peak values, while the overall damage degree of the rock mass in the exploded segment is the lowest. Conversely, specimens utilizing fine sand and steel balls as the cushion medium at the blast hole bottom of the blast hole demonstrate the lowest damage degree and strain peak values, with the overall damage degree of the rock mass in the exploded segment being the highest. Employing fine sand combined with steel balls as the cushion medium at the bottom of the blast hole can mitigate the impact of blasting stress waves and blasting gas, enabling the efficient utilization of explosive energy. This approach not only safeguards the integrity of the rock mass at the blast hole bottom but also strengthens the fracture degree of the rock mass in the exploded segment, thereby achieving a dual-purpose outcome. Highlights: Analysis of damage characteristics reveals that compared to foam, fine sand, and fine sand + steel ball as the cushioning medium of blast hole bottom can significantly reduce the degree of damage to the blast hole bottom. Analysis of strain evolution reveals that the specimen with foam at the blast hole bottom exhibits the highest strain peak value (2130με), whereas the specimen with fine sand + steel ball at the blast hole bottom demonstrates the lowest strain peak value (1608με). Employing fine sand + steel ball as the cushion material for the blast hole bottom enables the regulation of blasting stress waves and gas, facilitating the rational utilization of explosive energy, and achieving dual objectives [ABSTRACT FROM AUTHOR]

This paper studies the cushion performance of a range of sustainable cushion systems and applies two methods to estimate cushion curves from limited cushion test data. The methods employed were previously developed to allow for (1) the conversion of cushion curves representing a material's performance for a given drop height and sample thickness to alternative (non‐measured) drop heights and sample thicknesses and (2) generating a complete cushion curve for a given thickness and drop height from a single acceleration (shock) measurement. The results include those generated for medium‐density polyethylene (MDP) closed‐cell foam for benchmarking of the materials and to aid in validating the approach. The results indicate that predicting cushion curves from single shock measurements is generally accurate for polymeric materials (MDP closed‐sell foam and HDPE inflated bag) but much less so for organic materials (sugarcane bagasse and perforated cardboard). Finally, all alternative cushioning materials and systems evaluated are shown to only be effective for very low static stresses. This finding demonstrates that much higher volumes are required when using the alternative materials to achieve the same cushioning effectiveness as MPD foam. [ABSTRACT FROM AUTHOR]

AbstractThis study proposes a novel node-reinforced plate lattice (NRPL) by introducing the variable-thickness design into the nodes of the simple cubic (SC) plate lattice. The NRPL specimens are fabricated via laser powder bed fusion (L-PBF) using stainless steel 316 L powders. Compression experiments and numerical simulations are employed to investigate the mechanical responses and deformation mechanisms of the NRPL. The results reveal that the NRPL exhibits significantly enhanced energy absorption (EA), reduced initial peak stress and smooth stress fluctuations. In comparison to the SC plate lattice, the NRPL shows an increase in specific EA (SEA) and crash load efficiency (CLE) by 35.7% and 58.4%, respectively. Additionally, the NRPL exhibits excellent EA performance compared with most existing lattice structures. The NRPL proposed in this study holds promise as an ideal cushioning and energy-absorbing material, providing valuable insights for engineering applications in buffering and EA. [ABSTRACT FROM AUTHOR]

The pursuit of materials that offer both wear comfort and protection for functional and protective clothing has led to the exploration of weft-knitted spacer structures. Traditional cushioning materials such as spacer fabrics and laminated foam often suffer from deformation under compression stresses, thus compromising their protective properties. This study investigates the enhancement of the force absorption, stress–strain, and thermal properties of weft-knitted spacer fabrics with inlays. Surface yarns with superior stretchability and thermal properties are used and combined with elastic yarns in various patterns to fabricate nine different inlay samples. The mechanical and thermal properties of these samples are systematically analyzed, including their compression, stretchability, thermal comfort, and surface properties. The results show that the inlay spacer fabric exhibits superior compression properties and thermal conductivity compared to traditional laminated foam and spacer fabrics while maintaining stretchability, thus providing better performance than traditional fabrics for protective clothing and wearable cushioning products. This study further confirms that the type of inlay yarn and inlay structure are crucial factors that significantly influence the thermal, tensile, and compressive properties of the fabric. This research provides valuable insights into the design and development of advanced textile structures to improve wear comfort and protection in close-fitting apparel applications. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study investigated the development of mycelium-based biofoams as sustainable cushioning materials using Pleurotus ostreatus and Lentinus squarrosulus, combined with different sawdust substrates, and subjected to various pressing methods. The results indicated significant effects of mushroom species, sawdust type, and pressing method on the properties of biofoams. Growth rate, morphology, chemical composition, physical and mechanical properties, water resistance, and cushioning factor were evaluated. The results indicated that Lentinus squarrosulus (LS) exhibited faster growth rates (up to 14.37 mm/day) and produced biofoams with superior properties compared to Pleurotus ostreatus (PO). Core wood (CW) sawdust generally resulted in biofoams with lower density (0.1–0.3 g/cm3), lower shrinkage (7.17%–11.41%), and better shock absorption properties (cushion factor of 4.45–4.73). Hot pressing (HO) consistently produced biofoams with higher density (up to 0.31 g/cm3), improved mechanical strength (compression strength up to 0.53 MPa), and enhanced hydrophobicity (water contact angle up to 102.03°) but slightly reduced the shock absorption performance. Biofoam made from LS cultivated on CW sawdust and pressed using hand-packing (HP) exhibited superior shock absorption properties, achieving a cushion factor of 4.45 comparable to expanded polystyrene (EPS) foam. The findings demonstrated that certain combinations of sawdust types and pressing methods can optimize the performance of mycelium-based biofoams, making them viable for sustainable packaging applications. This study highlighted the potential of mycelium biofoams as an eco-friendly alternative to conventional packaging materials, thereby decreasing environmental impact and promoting a sustainable future. [ABSTRACT FROM AUTHOR]

Cellulose‐based aerogels possess satisfactory sustainability, porosity, and resilience, which are promising materials to replace traditional petroleum‐based foams. However, the viscous aggregation formed between hydrophilic fibers and the pore collapse caused by weak support force pose challenges for their further applications. Here, a load‐bearing structure‐inspired cellulose‐based aerogel is innovatively developed with excellent elasticity and water tolerance through surface‐interface modulation. Specifically, cellulose and polyvinyl alcohol (PVA) form interwoven skeletons by non‐directional freeze drying. Crucially, the rhamnolipid surfactant assists in forming stable and uniform bubbles, and drives the regularization of frame structure during the freezing process, promoting the construction of refined mechanical structures. Besides, the interfacial enhancement by esterification reaction of citric acid and the encapsulation by hydrophobic silane via chemical vapor deposition endow aerogels with better resilience and water tolerance. The as‐prepared aerogels can withstand intensive compression cycle tests and possess the ability to rebound over 10 times underwater. Even after 12 h wet treatment, the strain and stress loss respectively decrease by ≈55.5% and ≈14% compare with the initial unregulated aerogels after 500 cycles of 80% compression. Surprisingly, they have excellent cushioning performance beyond expanded polystyrene (EPS) and expanded polyethylene (EPE) in simulated road transportation packaging applications, indicating their potential in new‐generation cushioning materials. [ABSTRACT FROM AUTHOR]

Variable valve actuation (VVA) systems based on electromechanical valve actuators (EMVAs) enable a flexible operation and management of internal combustion engines that results in a reduction of pollutant emission and fuel consumption while improving engine power and efficiency. However, to achieve the benefits promised by EMVAs, it is of utmost importance to guarantee the catch of the valve by the system magnets with an acceptable impact speed of the valve at the end‐strokes. Valve catching failures can severely damage engine valves while high impact speeds induce mechanical wear and unacceptable noise. The soft landing control of the valve at the end‐strokes is challenging because of system nonlinearities, parameter uncertainties, and external disturbances. The complexity of the control design increases further when industrial cost‐effective solutions are sought. This paper presents a novel solution for reducing the impact speed of the valve without the use of costly position valve sensors. The proposed solution leverages on a small hydraulic damper (HD) embedded into the EMVA and a feedback cycle‐by‐cycle controller. The passive element reduces the impact speed while the controller adjusts at every engine cycle the EMVA coil currents based on pressure peaks detected in the HD to guarantee valve catching while steering the impact speed toward its minimum. The design of the controller exploits a physics‐based model that maps the pressure peak in the HD onto the impact speed and a gradient descent algorithm is adopted searching the minimum. The closed‐loop permanence is assessed in simulation by using an experimentally validated EMVA model and considering detailed dynamics of the HD. Numerical results show the ability of the proposed control architecture to reduce the impact speed and its robustness to parameters variations (oil temperature) and external disturbances (gas pressure forces). [ABSTRACT FROM AUTHOR]

Introduction: Elastic cushioning materials protect human tissue from injury by absorbing impact energy and delaying its transfer. However, the potential compromise in force delivery to the hitting target remains unknown. Methods: To examine if silicone cushioning compromises punch force delivery to a hitting target, a double-blind crossover trial with 12 elite boxers was conducted following material tests. Each boxer delivered five maximal punches under two conditions: silicone-hand wrapping and gauze-hand wrapping, in counterbalanced order, with a 3-day interval between sessions. Force distribution along the Z-axis indicated the punch's intended direction, while forces along the X and Y axes represented force dissipation toward unwanted direction. Results: The material tests (based on ASTM International, West Conshohocken, PA, USA) demonstrated substantially higher compression to disruption for silicone than gauze of similar thickness. During the punching trials, the silicon-based hand wrapping exhibited slightly higher total force production (436 ± 33 N vs. 372 ± 12 N, p < 0.001) than the gauze-based hand wrapping. Moreover, force wastage, calculated as the sum of forces along the X and Y axes vs. the total force produced in percentage, was notably lower for silicone material (2.0% wastage) compared to gauze (3.8% wastage) (p < 0.001). The use of silicone materials lengthened the contact time between the punching fist and the hitting target from 35 ms to 50 ms (p < 0.001). Conclusion: The elastic cushion does not compromise the force delivery of the boxing glove to the hitting target. Instead, it appears to allow for additional maneuvering time for alignment during the fist-target contact with higher impact. [ABSTRACT FROM AUTHOR]

Three-dimensional-printed silicone rubber foams, with their designable and highly ordered pore structures, have shown exceptional potential for engineering applications, particularly in areas requiring energy absorption and cushioning. However, optimizing the mechanical properties of these foams through structural design remains a significant challenge. This study addresses this challenge by formulating the research question: How do different 3D-printed topologies and printing parameters affect the mechanical properties of silicone rubber foams, and how can we design a novel topological structure? To answer this, we explored the mechanical behavior of two common structures–simple cubic (SC) and face-centered tetragonal (FCT)–by varying printing parameters such as filament spacing, filament diameter, and layer height. Furthermore, we proposed a novel two-level 3D-printed structure, combining SC and FCT configurations to enhance performance. The results demonstrated that the two-level SC-SC structure exhibited a specific energy absorption of 8.2 to 21.0 times greater than the SC structure and 2.3 to 7.2 times greater than the FCT structure. In conclusion, this study provides new insights into the design of 3D-printed silicone rubber foams, offering a promising approach to developing advanced cushioning materials with superior energy absorption capabilities. [ABSTRACT FROM AUTHOR]

To avoid microplastic pollution, there is an urgent need to replace fossil-based cushioning materials in packaging with easily recyclable alternatives. Here, we investigated the potential of lightweight cellulose fibre materials as a solution for mechanical protection. The quasi-static compression was studied among a vast set of 129 different foam-formed trial points with material density ranging from 21 kg/m3 to 123 kg/m3. The trial points included two different fibre types, bleached softwood kraft pulp (BSKP) and bleached chemithermomechanical pulp (CTMP), with varied refining level, pulp consistency, foaming conditions, surfactant type, strength additives, and final material density and thickness. Besides a correlation analysis of factors affecting compression stress and resilience, the results were reflected against a new theoretical prediction of energy absorption for an ideal low-density random fibre network. The theory predicts the initially-high cushion factor to rapidly drop down to the level of 4‒5 at 40‒80% compression. A similar behaviour was seen among the actual samples, despite their various non-ideal features. At 50% compression, the average cushion factor across the whole data set was 4.84 ± 0.10, being close to the theoretical prediction of 4.61 for the ideal case. The smallest cushion factor of 3.6 was found for a CTMP sample. The recovery from compression varied slightly among the samples and appeared highest for the material density of 60‒100 kg/m3, following the predicted proportion of non-buckled fibre segments. According to the results, cellulose fibre-based cushions have a soft initial response, which is preferable for fragile items. [ABSTRACT FROM AUTHOR]

A frequency up-conversion piezoelectric energy harvester (FUC-PEH) consists of a force amplifier, a piezoelectric stack, a low-frequency oscillator (LFO), and a stop limiter. The force amplifier generates the amplification of stress on the piezoelectric stack. The LFO, comprising a spring and a mass block, impacts the stop limiter during vibration to induce high-frequency oscillations within the piezoelectric stack. In this paper, we represent and simplify the FUC-PEH as a lumped-parameter model based on piezoelectric material constitutive equations and structural dynamic theories. Using the electromechanical analogy, we developed an equivalent circuit model (ECM) of the FUC-PEH. A parametric study was performed to investigate the impact of system parameters, such as spring stiffness and concentrated mass, on the FUC-PEH performance. The collision-induced amplitude truncation (AT) effect enlarges the operation bandwidth. ECM simulations show that low-frequency input excitation is converted into a high-frequency output response, enhancing the energy conversion efficiency. Furthermore, we aimed to improve the FUC-PEH's performance using a synchronous electric charge extraction (SECE) circuit. Using the ECM approach, we established a system-level model that considers the electromechanical coupling behavior. The simulation results provide insights into the performance of FUC harvesters with SECE circuits and offer valuable design guidance. [ABSTRACT FROM AUTHOR]

Yaozhou Kiln is a famous ancient center for celadon production in China, located in present-day Shaanxi Province. While analyzing its olive-green celadon produced during the Song Dynasty, a common occurrence of brownish base (foot and bottom) was observed. This phenomenon can also be found in porcelain produced at other kilns in China and Vietnam. However, previous research has not systematically explored the coloration mechanism behind it. Through different analytical methods, coupled with reproduction firing experiments, this paper concludes that the brownish base is attributed to the diffusion of iron from the body and sand cushion into the thinly applied glaze on the base, as well as the crystallization formed by the combination of the sand cushion and the surface glaze. Factors influencing the depth of the brownish color include: (1) the iron content of the body; (2) the thickness of the base glaze; and (3) the sand cushion material. [ABSTRACT FROM AUTHOR]

Lycium barbarum L. (L. barbarum) is an economic crop with high added value and profit. Vibration harvesting is a suitable mechanized harvesting method for L. barbarum. It bruises easily during harvesting due to the softness and vulnerability of fresh ripe fruit, resulting in economic losses. This study analyzed the fruit drop and collision during vibration harvesting. High-speed photography was used to obtain the impact speed and angle of the falling fruit, and a kinematic analysis of the collision with the collection surface was conducted. The majority of the fruit had an impact speed of 3-6 m/s and an impact angle of 30-90° with the collection surface. A drop test was conducted to assess fruit bruising, and the impact speed was converted to the drop height. An orthogonal rotation experiment was conducted, and mathematical model was established between the drop height, impact angle, and impact material, and the fruit bruise rate, maximum impact force, recovery coefficient, and impact time. The effects of the factors on the fruit bruise rate, maximum impact force, recovery coefficient, and impact time were analyzed. The test results show that a vibration harvesting device for L. barbarum should be designed to reduce the height between the fruit and the collection surface and utilize a tilted collection surface and high cushioning materials to reduce the fruit bruising. This study provides guidance for subsequent research on the bruising of L. barbarum during vibration harvesting and harvester design. [ABSTRACT FROM AUTHOR]

Handling potatoes individually or collectively in packages can create opportunities for potatoes to develop quality defects including blackspot and shatter bruise. Three trials were conducted to examine how handling packaged potatoes can influence the risk for physical damage including shatter and blackspot bruise. An impact recording device was used to record peak acceleration (max g-force) in common fresh market packaging options (boxes or bales) at four drop heights (15 to 91 cm) on to three different surface types. When boxed potatoes were dropped onto concrete or a plastic slip, the potatoes on the bottom of the box had the highest risk of damage (greater than 100 g-force). When drop heights were lowered, or when cushioning material was added to hard surfaces (e.g., wooden pallet on top of concrete floor), the risk for impact damage was decreased throughout the box. When palletizing boxed potatoes, the risk of bruise decreased after the first layer was stacked on the pallet. Drop heights need to be below 15 cm, especially when making the first layer in a palletized stack of packaged potatoes to reduce potential bruising. The risk of high peak accelerations was not seen in the dropped or stationary bales for any of the drop heights examined. This study provided information for educating personnel on handling packaged potatoes and determining situations in which robotic stacking equipment needs to be adjusted to lower drop heights of packaged potatoes. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Impacts occur everywhere, and they pose a serious threat to human health and production safety. Flexible materials with efficient cushioning and energy absorption are ideal candidates to provide protection from impacts. Despite the high demand, the cushioning capacity of protective materials is still limited. In this study, an integrated bionic strategy is proposed, and a bioinspired structural composite material with highly cushioning performance is developed on the basis of this strategy. The results demonstrated that the integrated bionic material, an S‐spider web‐foam, has excellent energy storage and dissipation as well as cushioning performance. Under impact loading, S‐spider web‐foam can reduce peak impact forces by a factor of 3.5 times better than silicone foam, achieving unprecedented cushioning performance. The results of this study deepen the understanding of flexible cushioning materials and may provide new strategies and inspiration for the preparation of high‐performance flexible cushioning materials. [ABSTRACT FROM AUTHOR]

Due to the thickness of the spacer fabric, it is usually assembled in a multi-layered manner as a cushion material. However, few studies have been conducted on the compression properties of the multi-layered spacer fabrics. Firstly, this paper analyzes the factors affecting the compression properties of multi-layered spacer fabrics, and explains the influencing mechanisms. Results show that the fixing condition between the sample and the indenter, the fixing condition between layers, the overlaying direction and the compression speed have little effect on the compression property. However, when overlaying spacer fabrics with different moduli, a better compression property can be obtained by placing the fabric with a higher modulus on top. Secondly, this paper focuses on the relationship between the layers and the compression property of the spacer fabrics. It shows that the relation between the compression work and the number of layers is linear, with a high correlation coefficient. The relationship between the modulus and the number of layers is in the form of a cubic function with a good correlation coefficient. Finally, the Kelvin model is modeled and is found to be suitable for characterizing the stage II compressive properties of multi-layered spacer fabrics. The above quantitative analysis provides theoretical support for the design of cushion materials with different moduli and support performance in different regions, and has practical guiding significance. [ABSTRACT FROM AUTHOR]

Objective: The consequences of falls in the elderly are severe, ranging from skin abrasion to hip fracture, which is very easy to cause death. Using advanced technology to develop anti-fall clothing that meets the needs of the elderly can play a significant role in protecting the elderly. By reviewing and analyzing the existing literature on the importance of fall protection clothing in reducing falls and protecting the body of the elderly, it is hoped to explore further research that needs improvement. Methods: Guided by the preferred reporting items for systematic reviews and meta-analyses, eight related studies were identified through Web of Science, Scopus and Chinese National Knowledge Infrastructure. The research objects, approaches, material and equipment, protection principle, and survey results are extracted. Results: Two articles verified the fall detection algorithm adopted in the research through experiments, which significantly improved fall detection accuracy. Six papers found that selecting appropriate cushioning materials can effectively reduce the consequences of falls of the elderly through experimental comparative analysis. Finally, three attributes for significant design value are drawn: (1) size and fit; (2) cushioning materials; (3) wearable sensing elements. Conclusions: Anti-fall clothing can effectively protect the elderly when they fall. Further design experiments are needed to select appropriate cushioning materials and wearable sensing elements based on anthropometry and aesthetics to design the style and structure of the garment to achieve the purpose of protecting the elderly. [ABSTRACT FROM AUTHOR]

Three-dimensional spacer fabric is a type of one-piece sandwich structure consisting of two outer layers and vertical and inclined spacer monofilaments. It behaves like a cushioning material, having linear, plateau, and densification stages under compression. This article elucidates the compression mechanism of a typical spacer fabric in terms of global deformation, local deformation, and internal contact behavior of spacer monofilaments through finite element simulation. While the linear stage is post-buckling of spacer monofilaments with tight constraints, the plateau stage is a combination of post-buckling, torsion, rotation, and contact of spacer monofilaments. The densification stage is attributed to the contact between spacer monofilaments and outer layers, which decreases the effective length to bear the load and enhances the constraints on the spacer monofilaments. The vertical spacer monofilaments with almost triple the normal strains of the inclined ones contribute more to compression resistance. [ABSTRACT FROM AUTHOR]

In this research, a new type of flexible cushioning material was fabricated from silicone rubber reinforced with different lengths and contents of flax short fibres and warp-knitted spacer fabric (FSR-WSF). The pressure reduction property and energy absorption capability of the FSR-WSF were thoroughly studied based on the plane compressive test. Furthermore, the obliquity model was utilized to characterize the dispersion of WSFs with different structures. The results demonstrated that a larger modulus and a smaller fracture strain were obtained for silicone rubber reinforced with 1.26% short flax staple fibres that were 2.5 mm in length. Additionally, a remarkable pressure reduction property was exhibited by an FSR-WSF containing 2.16% 3.5 mm short flax fibres, where the values of csc α and csc β were 1.05 and 1.57, respectively. The results illustrated that the pressure reduction property of the FSR-WSF was the result of coupling between its internal components. These findings could contribute significantly to the development of composites reinforced by warp-knitted spacer fabrics. [ABSTRACT FROM AUTHOR]

A reinforced eco-friendly cushioning material (ECM) comprising starch and cellulose material was developed. The ECM was prepared based on the starch type and cellulose material content; it was compared with commercial CMs. Different sizes of refined pulp (RP) and microfibrillated cellulose (MFC) were manufactured from hardwood bleached kraft pulp via beating and grinding, respectively. Thereafter, amylose-containing corn starch (CS) or amylopectin-only-containing glutinous rice starch (GS) was mixed with the manufactured cellulose materials. A slurry comprising starch and cellulose materials was homogenized for 2 min and lyophilized to prepare the ECM, after which the structure and strength characteristics of the prepared ECM were evaluated. The GS-prepared ECM produced a plate-like internal structure because of its amylopectin content, and amylose-containing CS exhibited a net-like shape. The cellulose materials offered support between starches with plate-like or net structure ECMs, and the pore shape was formed by adding MFC. As the cellulose material content increased, the strength of the ECM increased compared with that of the commercial CMs. Thus, ECMs with higher strength than their commercial counterparts could be manufactured with GS and cellulose materials. [ABSTRACT FROM AUTHOR]

The aim of this study is to establish a valid and efficient inspection method for assessing macroscopic mechanical property degradation of ethylene-propylene-diene-monomer (EPDM) by examining crosslinked density variation of microstructure. Inspection methods of mechanical behavior and crosslinked density are based on static compression and 1 H double quantum nuclear magnetic resonance ( 1 H DQ NMR), respectively. After introducing the hyperelastic constitutive model proposed by Yuhai Xiang and designing different conditions of heat-aging and fatigue load, the significant mechanical parameter variation is observed for the hyperelastic constitutive model. The significant impacted factors include heat-aging time and fatigue load except for heat-aging compression strain. The phenomenon is consistent with 1 H DQ NMR test results. We further analyze relationship between macro and micro properties of EPDM. After importing fitting assumption and limitation of 1 H DQ NMR data to control fitting error, the fractions of dangling and sol chains f and residual dipolar couplings constants D res in 1 H DQ NMR parameters show moderate negative ( R 2 = 0.6227 ) and high positive ( R 2 = 0.7312 ) correlation with G c of constitutive model parameters, respectively. Thus the validity and precision of inspection method is proven to estimate behavior variation of EPDM and hopefully the method can be extended to analyze other rubber-like materials. [ABSTRACT FROM AUTHOR]

The composite cushion of sand and non-vented flexible airbags offers a promising application in protecting galleries against rockfall. This research focuses on a numerical study that aims to more effectively characterize the global mechanical behavior of the cushion rock shed system with sand layer, as well as the sand-airbag composite cushion system. The impact response properties during a collision between cushion and rockfall, including, the penetration depth, and the vertical displacement of the plate, the impact forces on the gallery surface, and the impact forces on the bottom of the RC slab were studied. It was found the impact force affected the surface of the cushion and the bottom of the RC plate with the type of cushion materials. The impact forces of the novel composite cushion and vertical deformation of the plate are lower than the sand cushion, while the penetration depth of the granular cushion is greater than that of the composite cushion. It was also found that increasing the thickness of the sand layer can only reduce the impact forces on the bottom of the slab and increase the impact forces on the upper surface of the cushion. On the other hand, a new calculation method based on dynamic analysis is proposed to determine the impact force on the bottom of the RC slab. The proposed method was verified by comparison with the numerical and laboratory results. [ABSTRACT FROM AUTHOR]

This paper aimed to experimentally clarify the dynamic crushing performance of expanded polyethylene (EPE) and analyze the influence of thickness and dropping height on its mechanical behavior based on the stress–energy method. Hence, a series of impact tests are carried out on EPE foams with different thicknesses and dropping heights. The maximum acceleration, static stress, dynamic stress and dynamic energy of EPE specimens are obtained through a dynamic impact test. Then, according to the principle of the stress–energy method, the functional relationship between dynamic stress and dynamic energy is obtained through exponential fitting and polynomial fitting, and the cushion material constants a, b and c are determined. The maximum acceleration-static stress curves of any thickness and dropping height can be further fitted. By the equipartition energy domain method, the range of static stress can be expanded, which is very fast and convenient. When analyzing the influence of thickness and dropping height on the dynamic cushioning performance curves of EPE, it is found that at the same drop height, with the increase of thickness, the opening of the curve gradually becomes larger. The minimum point on the maximum acceleration-static stress curve also decreases with the increase of the thickness. When the dropping height is 400 mm, compared to foam with a thickness of 60 mm, the tested maximum acceleration value of the lowest point of the specimen with a thickness of 40 mm increased by 45.3%, and the static stress is both 5.5 kPa. When the thickness of the specimen is 50 mm, compared to the dropping height of 300 mm, the tested maximum acceleration value of the lowest point of the specimen with a dropping height of 600 mm increased by 93.3%. Therefore, the dynamic cushioning performance curve of EPE foams can be quickly obtained by the stress–energy method when the precision requirement is not high, which provides a theoretical basis for the design of cushion packaging. [ABSTRACT FROM AUTHOR]

An experimental testing system for the two-dimensional (2D) fuze overload loading process was designed to address the loading issues of recoil overload and centrifugal overload in fuze safety and arming (S&A) device. By incorporating centrifuge rotation energy storage, impact acceleration simulation, and equivalent centrifugal rotation simulation, a block equipped with a fuze S&A device accelerated instantly upon having impact from a centrifuge-driven impact hammer, simulating recoil overload loading. The impact hammer was retracted instantaneously by adopting an electromagnetic brake, which resulted in the centrifugal rotation of the block around its track, to simulate the centrifugal overload loading. The dynamic equations of the experimental testing system and the equations of impact hammer motions were established, whereby the rotation speed of the centrifuge and the braking force of the electromagnetic brake were calculated and selected. A dynamic model of the collision between the impact hammer and block was established using ANSYS/LS-DYNA software for simulation analysis. The acceleration curves of the recoil overload and centrifugal overload with variations in the centrifuge speed, cushion material, and buffer thickness were obtained, which verified the feasibility of the proposed loading simulation method. Two-dimensional overload loading simulation tests were performed using the developed experimental testing system, and the acceleration curves of the recoil overload and centrifugal overload were measured. The test results indicated that the proposed system can accomplish 2D overload loading simulations for a recoil overload of several 10,000× g and centrifugal overload of several 1000× g. [ABSTRACT FROM AUTHOR]

The purpose of this work is to provide support for the design of cushioning packaging materials for products with unbalanced mass distributions. A mathematical model of the cushioning packaging system is established and the fourth-order Runge–Kutta method is used to compare the vibration response of products with balanced and unbalanced mass. Finite element simulations are conducted to demonstrate the feasibility of the proposed method of optimizing the design of cushioning packaging materials for products with unbalanced mass distributions using various damping materials. The simulation results are verified by experiments. The results show that the magnitude of the mass offset has a large effect on the acceleration of damped cushioning packaging systems for products with unbalanced mass. The vibration response can be corrected by appropriately increasing the damping coefficient at the mass offset end, thus providing an effective method of optimizing the design of cushioning packaging for products with unbalanced mass. [ABSTRACT FROM AUTHOR]

Energy‐absorbing materials are widely used under certain high‐frequency scenarios, such as cargo packaging or sport protection. Though negative stiffness mechanical metamaterials have many distinctive advantages, fairly low strength and poor specific energy absorption unfortunately limit their present industrial applications. Inspired by the excellent cushioning performance of the paw pads of mammals, a novel flexible energy‐absorbing negative stiffness mechanical metamaterial is proposed herein. Results show that the presented metamaterial outperforms traditional packaging materials with respect to cushion performance. Moreover, a performance programming strategy is proposed to achieve multistage tuning between large energy absorption and high rebound properties. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tribologie und Schmierungstechnik is the property of Narr Francke Attempto Verlag GmbH & Co.KG and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Composites derived from plant fibers are promising reinforcing materials for engineering because of their renewable and easily available characteristics. In this study, a simple pretreatment method was developed to fabricate structurally intact bamboo cellulose scaffolds. Water-stable, flexible, impact-resistant, and high damping ratio bamboo-based rubber composites were synthesized using carboxylated styrene-butadiene latex-impregnated 3D bamboo scaffolds. The composites were prepared by "Ethanol dehydration-delignification-polymer redistribution" strategy. The bamboo cellulose aggregate state structure and multiple crosslinked networks in the composite systems endowed the composites with strong mechanical and damping properties. The prepared composites had a high tensile strength, 67 times that of pure rubber (101.58 MPa and 1.25 MPa), which is higher than that of reported polymer-based vibration-damping materials, and the hydrostability was also significantly improved. The composites exhibited the characteristic viscoelasticity of polymers, with a recovery angle of 132° after 1000 extreme 180° flexion tests. More importantly, composites maintain a higher effective damping factor (Tan δ = 0.5) at room temperature. These bamboo-based rubber composites with excellent comprehensive performances have great potential for engineering applications, particularly for vibration damping, lightweight design, and flexible materials. [Display omitted] • Flexible and impact-resistant bamboo-rubber composites was developed innovatively. • The "alkali pretreatment- autologous crosslinking- delignification" strategy was proposed. • The composites achieved excellent water stability, high strength, and effective damping factor. • The prepared composites have great potential in engineering applications. [ABSTRACT FROM AUTHOR]

Traditional cushioning package materials, such as Expended Polystyrene (EPS) and Expanded Polyethylene (EPE), were made with petroleum-based plastics, which are harmful to the environment. It is crucial to develop renewable bio-based cushioning materials that can replace the aforementioned foams due to the rising energy demands of human society and the depletion of fossil fuels. Herein, we report an effective strategy for creating anisotropic elastic wood with special spring-like lamellar structures. Selective removal of lignin and hemicellulose by simple chemical treatment and thermal treatment of the samples after freeze-drying results in an elastic material with good mechanical properties. The resulting elastic wood has a reversible compression rate of 60% and a high elastic recovery (99% height retention after 100 cycles at 60% strain). Drop tests revealed that the elastic wood has excellent cushioning properties. In addition, the chemical and thermal treatments also enlarge the pores in the material, which is favorable for subsequent functionalization. By loading the elastic wood with a muti-walled carbon nanotube (MWCNT), electromagnetic shielding properties are achieved, while the mechanical properties of elastic wood remain unchanged. Electromagnetic shielding materials can effectively suppress various electromagnetic waves propagating through space and the resulting electromagnetic interference and electromagnetic radiation, improve the electromagnetic compatibility of electronic systems and electronic equipment, and ensure the safety of information. [ABSTRACT FROM AUTHOR]

With the continuous increase of subway operating mileage, the problem of subway vibration has become more and more significant. Nowadays, the point-supported floating-slab track is recognized as the best method to control track vibration, which is mainly designed based on the mass-spring-damping theory. How to further improve the vibration control ability of the point-supported floating-slab track? In this paper, a new type of rubber point-supported floating slab track is designed based on the local resonance theory. Through calculation and dynamic test, it is obtained as follows: (1) The band gap of the point support structure by local resonance type depends on the two vertical vibration modes. (2) As the elastic modulus of the cladding layer increases, the bandwidth of the band gap of the corresponding structure increases significantly. (3) The increase of the vibrator density can increase the bandwidth, while reducing the start and stop frequencies, which is beneficial to attenuate the resonance of the floating-slab track. (4) The cushion material parameters of point support structure by local resonance type 2 will not affect the band gap. The increase in sleeve density will reduce the band gap, which is not conducive to vibration reduction. Local resonance type floating-slab track will be the development direction of track vibration-reduction measures in the future. [ABSTRACT FROM AUTHOR]

The cushioning behaviour of granular materials, such as sand and gravel, has been studied for the rational design and performance evaluation of a rock shed intended for rockfall protection. The shape of the collision surface of a falling mass strongly affects the impact force waveform of the falling mass. However, the control factors for generating impact force waveform have not been fully clarified. Previous studies have shown that the maximum transmitted impact force acting on the top plate of a rock shed through a cushioning material depends not only on the maximum impact force acting on the falling mass but also on its duration. To accurately predict the maximum transmitted impact force acting on a structure, understanding the generation mechanism of the impact force waveform acting on the falling mass is necessary. These control factors were investigated through the two-dimensional (2D) discrete element method (DEM) analysis. It was shown that the mean principal stress of particles around a falling mass increased with the loading velocity of the falling mass. Based on this result, an analytical model for estimation the impact force waveform of the falling mass was proposed. The validity of the proposed method and the control factors estimated via simulations was confirmed by comparing the results obtained by the proposed method with 2D DEM simulation results and experimental results. This study contributes to the elucidation of the deformation mechanism of soil under high-speed loading and development of rational countermeasures considering the deformation behaviour of a sand cushion. [ABSTRACT FROM AUTHOR]

Fruits, essential in human nutrition, go through many stages until they reach the consumption stage. Brıise may occur on the fruit during loading, unloading, and processing. One of the options applied to prevent bruises to fruits throughout the supply chain is to package cushioning materials. This study investigated the number of bruises caused by applying impact energies to the covered and uncoated (bare) persimmon fruits with foam net material. Impact energy applications were carried out with the developed pendulum impact test setup. Dynamic loadings at different impact energy levels, low (0.03 J), medium (0.06 J), and high energy (0.11 J) were applied to three other regions of persimmon fruits (blossom side, lateral diameter, and stem side). Statistical analysis showed that the effect of impact energy on bruise volume was significant (p ˂ 0.01). The study found a linear relationship between bruising volume on persimmons and impact energy. According to the experiment results, it was determined that the bruise volume values of persimmons with foam net used as cushioning material were significantly less than the bare persimmons. As a result of the applied impact energies, it was determined that the average bruise volume of the persimmons was 225.74 mm3 in the bare ones and 21.29 mm3 in the ones covered with foam net. It was also revealed that the blossom side of the persimmon was the most sensitive to impact energy, and the lateral diameter side was the most durable. Practical Applications: Mechanical bruises to fruits and vegetables during post‐harvest processing can be significant. Bruise‐sensitive fruits such as persimmon increase the size of bruises due to falling from height during filling and unloading. Understanding where and how large the bruising effects caused by impact energies are can help reduce fruit bruises. Packaging practices, which are ways to prevent fruit bruising, play an important role in prolonging the shelf life of the fruit and reducing the risk of physical bruising. In the study, the effect of the cushioning material on the prevention of the size of bruises caused by the impact energy effect on the persimmon fruit was investigated. It is aimed to compare the bruise amount of foam‐coated and non‐foam‐coated persimmon fruits by considering the fruit regions in the applications performed with the pendulum test setup. [ABSTRACT FROM AUTHOR]

This paper focuses on predicting the shape, duration, and peak magnitude of the displacement, velocity, and acceleration curves while dropping weight over a viscoelastic fractal cushioning packaging system. Furthermore, to capture high-frequency harmonic components observed during the impact time span, the approximate frequency–amplitude expression of the governing equation of motion will be obtained via an ancient Chinese algorithm and He's formulation by assuming initial trial solutions based on Jacobi elliptic functions. Numerical simulations confirmed the ability of the Jacobi elliptic functions to capture high-frequency harmonics observed during the cushioning packaging system dynamic response with a root mean square error (RMSE) value that does not exceed 0.0218, which is an indication of the great accuracy attained from our derived solution when compared to the exact numerical one. Furthermore, our derived approximate solution predicts that when a weight is dropped over the cushioning packaging, the cushion material with smaller porosity will absorb the produced kinetic energy faster. [ABSTRACT FROM AUTHOR]

In this study, the sensitivity of the drop response according to changes in material properties was analyzed to determine the material properties that have a dominant influence on energy absorption performance. Parametric analyses were performed using a spent nuclear fuel (SNF) transport cask as an example, wherein the parameters were the material properties related to the stiffness of the steel (the elastic modulus, yield strength, and tangent modulus) that constitutes an impact limiter installed in the SNF transport cask. On the basis of the analysis results, the absorbed impact energy and transmitted energy were quantitatively calculated and the variations in the structural response were identified. In addition, changes in the structural safety of the SNF transport cask were investigated. The results of this study suggest that material properties must be considered to effectively design a structure that absorbs impact energy. [ABSTRACT FROM AUTHOR]

Roughly 40% of patients undergoing radiation annually in the United States do so with palliative intent. Patients presenting with cancer-related pain are at increased risk of treatment-related exacerbation due to immobilization on a carbon fiber table, often without additional cushioning or supportive material for comfort. Acute, positional discomfort can heighten patient distress while leading to delayed or unsuccessful treatment delivery. Using commonly available cushioning materials, we evaluated the quality and reproducibility of palliative radiotherapy plans to identify clinically acceptable immobilization modifications. Nine immobilization variations were used for phantom-based CT-simulation—standard memory and egg crate foam, three different thicknesses of mattress pads, an alpha cradle, a vac loc bag (with and without standard memory foam) and a hover mattress. Two beam arrangements (AP/PA and AP/RPO/LPO) were created for a thoracic spine target, and treatment plans were generated with three different beam energies (6MV, 10MV, 15MV). Clinical goals for target coverage and organs at risk were evaluated for each plan, with variations computed from an established standard—the vac loc bag. Plans were delivered to the phantom using the vac loc bag with and without memory foam immobilizations to test set up reproducibility by investigating the accuracy and precision of repeated alignment with cone beam CT (CBCT). Clinically acceptable plans, as defined by 95% CTV coverage at prescription dose, were achieved with AP/PA and AP/RPO/LPO beam arrangements for each immobilization material with variation ranging from -5.4% to 2.4%. Choice of immobilization device had minimal impact on relevant organs at risk, such as maximum skin dose, with a percent difference range of -1.9% to 1.4%. Beam energy proved to have more notable impact on dosimetric variation for target coverage, particularly with the AP/RPO/LPO beam arrangement. Average shifts in the XYZ planes were 1.7, 1.0 and 1.8mm (standard deviation (SD) 1.1-1.2mm) for the vac loc bag and 0.6, 0.7 and 0.9mm (SD 0.6-0.9mm) for the vac loc bag-memory foam combination respectively. Average rotational shifts for pitch, roll and yaw were 0.5, 0.4 and 0.3mm (SD 0.1-0.4mm) for the standard and 0.7, 0.5 and 0.4mm (SD 0.1-0.2mm) for the combination respectively. Preliminary analysis suggests that clinically acceptable palliative radiation plans can be feasibly and reproducibly achieved with commonly available cushioning materials, without meaningful decrease in target coverage, increase in dose to organs at risk, or compromise in set up accuracy and precision. Future directions include evaluation of these metrics for all immobilization variations, in addition to dose delivery with optically stimulated luminescent dosimeters. [ABSTRACT FROM AUTHOR]

Transient stability is a complex phenomenon presented in multi-machine and multi-converter systems, and it is still considered a key limiting factor for stressed power systems. The increasing integration of non-synchronous generation further emphasises the need to address the challenges of improving the transient stability faced by these power systems. Several studies have focused on developing control strategies for Grid-forming voltage source converter (GFM-VSC) to improve transient stability. These strategies include the use of current limiting algorithms and/or control of active/reactive power injections. This paper investigates the impact of fast voltage boosters (FVBs) and hybrid current limiters (HCLs) on transient stability of power systems with 100% grid-forming VSC-based generators. Short-circuit simulations and critical clearing time analysis are performed to evaluate the effectiveness of HCLs and FVBs in improving transient stability. The simulation results demonstrate the effectiveness of these approaches in avoiding the loss of synchronism. This research contributes to the current studies on transient stability in power systems and provides valuable insights into the potential of HCLs and FVBs as effective approaches to improve system stability. • Grid-forming (GFM) voltage source converters (VSC) and transient stability. • Hybrid current limiters (HCLs) and fast voltage boosters (FVBs) in GFM-VSCs. • FVBs in GFM-VSCs improve transient stability. FVB-L (local) and FVB-WACS (global). • HCLs in GFM-VSCs limit the converter's current and improve transient stability. • FVBs and HCLs are compatible and complementary. [ABSTRACT FROM AUTHOR]

Copyright of Nachrichten aus der Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

One of the important stages in the creation of the scientific and technical foundations for the calculation, design and manufacturing technology of the lowest heat-conductivity thermal protection from screen-vacuum thermal insulation (SVTI) is the development of a process for achieving the optimal vacuum P0 ≤ 10−3 Pa in the SVTI layers, since at this pressure, thermal conductivity (λeff) through the SVTI is carried out only due to the radiant (λrad) and contact-conductive (λk,k) components. It is proposed to obtain such a pressure in thermal insulation by using cushioning material in it, which was previously degassed in a separate vacuum chamber at 370−380 K for 12 h in order to remove water molecules from its structure and then replace them with nitrogen molecules. These molecules have 3−4 times less heat of adsorption; therefore they are pumped out faster. As a result, it becomes possible to accelerate (by ∼20 h) to achieve optimal vacuum in thermal insulation, as well as 11% lower effective thermal conductivity [equal to (14.1−14.3)⋅10−5 W/(m⋅K)]. The analysis carried out (according to the developed methodology) showed that the achieved optimal effective thermal conductivity of thermal insulation in a cryocontainers is determined by 33% of radiant thermal conductivity [4.7⋅10−5 W/(m⋅K)] and 67% of the contact-conductive component [9.4⋅10−5 W/(m⋅K)]. [ABSTRACT FROM AUTHOR]

A multifunctional composite composed of a spacer fabric and a porous graphene‐based aerogel is proposed for sensing and impact protection applications. The combination of the mechanical properties of the spacer fabric and the electrical properties of the graphene‐based aerogel provides a versatile composite material with a strain sensitivity of 1.48, a temperature sensitivity of −0.004 °C−1, and a protection factor of 45%. The material is also lightweight, hydrophobic, and thermally insulating. It is therefore suitable for both high‐temperature (nearly 180 °C) and low‐temperature applications. Consequently, the developed multifunctional composite has potential for use as a building material and as a smart cushion for healthcare. [ABSTRACT FROM AUTHOR]

The corrugated fibreboard was the dominated cushioning material before the advent of expanded plastic foams in the 1960s. With recent advances in packaging sustainability, the corrugated pads are again the research focus. This paper reviewed studies of corrugated fibreboard cushioning in areas of design and experimental evaluation. Since most of these research works were performed more than half a century ago, the historical data were reexamined and compared with the current practices. Previous and recent structure designs, represented by layered corrugated pads, tube, spring and zig‐zag components, were displayed and discussed. This study also reviewed studies investigating the crush resistance and cushion curves in hope to provide some practical guidance on prediction of cushioning performance. As an updated development by the author, this study presented cushion curves developed under three loading patterns, namely, column, underhang and overhang. Finally, the study pointed out that double dipping points and shift‐to‐right tendency on the cushion curves, as well as the long plateau on the stress–strain curves, are unique properties of corrugated fibreboard cushioning. Packaging engineers are suggested to factor in these properties in design for different applications. [ABSTRACT FROM AUTHOR]

The 3D lattice structure is a porous lightweight periodic structure with high specific stiffness and strength and has good energy absorption characteristics. In this study, flexible resin was used as the research material, and a microporous lattice structure with a periodic inner core was designed and fabricated using digital light processing 3D printing technology by vertical and horizontal printing, respectively. Quasi-static axial compression experiments were performed to study the mechanical properties and energy absorption properties of the porous lattice structure. At the same time, the cell body structure of an existing x-type unit was studied, and the ratio of the stress platform of the structure with different diameters and angle parameters was studied. In this study, after a combination of theoretical analysis, ANSYS finite element analysis and experimental verification, a certain angle of control was obtained, and the x-type porous lattice structure showed excellent energy absorption characteristics. The research results suggest broad applicability, and the structure can be used as an in vitro 3D scaffold material in skin tissue engineering component technology and can also be used as a high-quality cushioning or damping material in vibration and energy absorption applications. [ABSTRACT FROM AUTHOR]