Search

This study examines the effects of multilayering in sandwich panel composite structures with different corrugated core configurations under quasi‐static indentation loading. The panels were fabricated using woven glass fibers and epoxy resin via the Vacuum Infusion Process. Experiments were conducted using two hemispherical cylindrical indenters with a diameter of 20 mm (ID = 20 mm) and 10 mm (ID = 10 mm) and the behavior of the composite structure in terms of contact force and fracture mechanisms for different core corrugations (square and butterfly) were investigated in two ways with foam and without foam. The experimental results demonstrate that, among corrugated core geometries without foam, butterfly cores outperform square cores in terms of structural strength, maximum force, moment force, energy absorption, specific energy absorption, and displacement until full indentation. Moreover, the butterfly core shows a higher peak load and different failure mechanisms compared to the square core. Under loading with a 10 mm indenter, the butterfly core without foam only experienced perforation in the loading area, without fracture completely. Also, adding foam did not change failure mechanisms and mechanical behavior in the butterfly geometry. However, in the square geometry, foam filled gaps between the core, preventing fracture completely and leading to only perforation in the loading area, unlike the specimen without foam. The visual analysis during the quasi‐static indentation process revealed several significant damage mechanisms, including matrix cracking, fiber breakage, delamination, buckling and crushing of cell walls, damage to top sheets, core separation, and complete indentation of the samples. Highlights: Delamination and indentation failure mechanisms were seen on the butterfly core.Skin indentation and rib fracture failure mechanisms were seen on the square core.Butterfly corrugated cores revealed the best performance without/with foam.The core shape was more effective on the strength than the foam addition. [ABSTRACT FROM AUTHOR]

AbstractCoupled energy absorption effect between the aluminum foam and the thin-walled tube plays a significant role in the crushing process. Firstly, a composite structure filled with aluminum foam in a multi-cell conical tube is proposed. Secondly, the influence of structure parameters on coupled energy absorption is investigated. Thirdly, the energy absorption mechanism is analyzed. Additionally, the structure is subjected to multi-objective optimization. The results show that increasing structure parameters are beneficial to coupled energy absorption effect. In addition, there are SEA = 26.18 J/g and FP =86.22 kN for the optimal tube, which is superior to most existing aluminum foam-filled tubes. [ABSTRACT FROM AUTHOR]

This study investigated both the static and dynamic behavior of silicate materials through a series of experimental and numerical tests. Compression tests were conducted on cubic samples, three-point bending tests on beams, and perforation tests on silicate plates. In the compression tests, stress–strain curves were generated, enabling the calibration of the Concrete Damaged Plasticity (CDP) model for silicate materials. The tensile strength of the silicate was assessed using three-point bending tests, while dynamic perforation tests determined the impact resistance of silicate when subjected to a rigid projectile. The perforation tests provided insight into the failure mechanisms of silicate plates under projectile impact at velocities approaching the ballistic limit. Additionally, the numerical simulations for all the experimental tests were performed using the Abaqus software in order to validate the accuracy of the material behavior model and confirm the appropriateness of the calibrated parameters for the chosen model. The results showed a strong qualitative and quantitative correlation with the experimental data, demonstrating the robustness of the adopted approach. [ABSTRACT FROM AUTHOR]

This study investigates the quasi-static and viscoelastic properties of additively manufactured (AM) PETG reinforced with short carbon fibres. Samples were manufactured using different parameters in terms of the infill pattern, porosity, and annealing condition. Tensile and compressive tests were conducted to determine quasi-static properties such as Young's modulus and toughness, and dynamic mechanical analysis was used under a frequency sweep of 1–100 Hz to describe the viscoelastic behaviour of the composites. The major impacts and responses between the print parameters were quantified using Analyses of Variance (ANOVAs), which revealed the major contributor to each mechanical property. Fractography on the tensile samples using scanning electron microscopy demonstrated fibre pull-out, indicating poor fibre–matrix bonding, but also revealed interfacial bonding between raster lines in the annealed samples. This had a prominent effect on the properties of latitudinal samples where the force applied was perpendicular to the raster lines. Generally, porosity appeared to have the greatest contribution to the variance in the mechanical properties, with the exception of the tensile modulus, where the infill pattern had a more substantial effect. Annealing caused a consistent increase in the tensile modulus of the tested samples, which can be used to support the design and optimisation of AM parts when they are used under specific loading conditions. [ABSTRACT FROM AUTHOR]

The fracture behavior of bi-material made of Ni-Cr-B-Si hardfacing alloy deposited over SS316LN substrate was evaluated under quasi-static and dynamic loads. The crack growth started from notch made on the deposit side and progress toward the substrate deposit interface under both loading conditions was monitored. The displacement rate in quasi-static loading and the loading rate for dynamic loading varied and crack propagation was studied. It was observed that the crack was deflected at the interface and not penetrated to the substrate, irrespective of loading conditions. The reason for crack deflection at the interface was analyzed using the energy-based method. It is shown that the ratio of fracture toughness of the interface to that of the substrate (0.044) is lower than the ratio of energy release rate for the deflecting crack to that of the penetrating crack (0.235). Thus, this material combination satisfies the condition for crack deflection rather than penetration. The fracture toughness of the interface was estimated as ~ 68 MPa m1/2 and it falls between that of hardfacing alloy and SS316LN base metal. Optical and SEM examinations were conducted to corroborate the crack path deviations during crack growth. Results suggest that isolated cracks might be present on hardfaced coatings on critical components for which such cracks are usually not permitted. It may be allowed in preference to repair of these cracks, which is difficult and significantly increases the risk of additional cracks forming on the deposits because of the high susceptibility of the hardfacing alloy to cracking. [ABSTRACT FROM AUTHOR]

The electrode tabs of pouch cells are rigidly joined to the bus bar in a battery module to achieve an electric connection. The effect of abusive mechanical loads arising from crash-related deformation or the possible movement of battery cells caused by operation-dependent thickness variations has so far never been investigated. Three quasi-static abuse tests for the anode and cathode electrode tabs were conducted with pouch cells at 100% SOC. Tensile tests on the anode, cathode and pouch foil were performed in order to explain differences between the anode and cathode in the abuse tests. The experiments revealed different failure mechanisms for the anode and cathode electrode tabs. The cathode failed at an average maximum load of 940.3 N through an external rupture of the electrode tab. The anode failed at an average maximum load of 868.9 N through a rupture of the single electrode sheets and the opening of the pouch foil. No thermal runaway occurred for either cathode or anode. The results of this study reveal a more critical failure behavior for the anode electrode tab, which can be addressed in the future by adding a predetermined breaking point and adapting the geometry of the anode electrode tab. [ABSTRACT FROM AUTHOR]

Structures allowing their bases to uplift and rock during an earthquake event usually experience less damage; thus, they are more resilient to seismic hazards. Accurate simulation is critical to design and seismic performance evaluation of these flexible rocking structures. Motivated from this, this article presents a new rigid‐flexible coupled rocking model for numerical evaluation of flexible rocking structures under both cyclic and dynamic loadings. The key idea in the model formulation is that the total motion of flexible rocking structure can be decomposed into a rigid‐body motion and an associated flexible deformation. The flexible deformation of the rocking body is described using displacement field of classical Timoshenko beam. Using this approach and appropriate degrees‐of‐freedom (DOFs), the governing equations‐of‐motion for flexible rocking structures are formulated using the variational principle. Multiple springs with appropriate constitutive model are distributed along rocking base to represent the inelastic behavior of rocking body. Potential post‐tensioned tendons are also considered in this model. In addition, nonlinear stress distribution along the rocking base, which cannot be considered in existing flexible rocking model, is also incorporated in the developed model. The proposed model is subsequently validated against published experimental data through quasi‐static and shake table tests, showing good accuracy when the rocking structure is relatively stockier. Finally, a parametric investigation on the effect of flexibility, nonlinear stress distribution and yield stress of rocking body on the rocking response is performed. This preliminary investigation shows that influence of flexibility and yield stress is significant while impact of nonlinear stress distribution is minor. [ABSTRACT FROM AUTHOR]

This paper presents the process of conducting the structural analysis of AlAinSat-1 CubeSat through a numerical solution using Siemens NX. AlAinSat-1 is a 3U remote-sensing CubeSat carrying two earth observation payloads. The CubeSat is scheduled for launch on SpaceX Falcon 9 rocket. To ensure the success of the mission and its ability to withstand the launch environment, several scenarios should be analyzed. For AlAinSat-1 model the finite element analysis (FEA) method is used, and four types of structural analyses are considered: modal, quasi-static, buckling, and random vibration analyses. The workflow cycle includes idealizing, meshing, assembling, applying connections and boundary conditions, and eventually running the simulation utilizing the Siemens Nastran solver. The simulation results of all analysis types indicate that the model can safely withstand the loads exerted during launch. Also, the numerical results of the Command and Data Handling Subsystem (CDHS) module of AlAinSat-1 are experimentally validated through a vibration test conducted using an LV8 shaker system. The module successfully passed the test based on the test success criteria provided by the launcher.

In the current study, a new type of novel lattice structures with the concept of bio-mimicking three different nature-inspired designs from the honeycomb patterns, the overlapping phenomenon of the scales present on fish dermal layers, and scutes pattern observed from the top skin layers present on crocodile species are developed. These lattice structures are designed within a cubic volume of 30 mm. The design of lattice unit cells is made with two different geometrical sizes of 4 and 6 mm with different overlapping areas of 20, 30, 40, and 50% calculated from each cell area. All the unit cells' walls are maintained at 0.4 and 0.6 mm only. The specimens are modeled and manufactured through the VAT photopolymerization process, one of the significant additive manufacturing principles for great dimensional accuracy with negligible defects in 3D printing (3DP). The research approach used to develop lightweight bio-inspired structures has been laid out, starting with observing design that served as inspiration. The cured 3D-printed specimens are examined under quasi-static compressive loading carried out on all specimens as per ASTM 1621 standards to measure the crashworthiness response of designed specimens. The energy ingestion capacity of all the specimens is assessed. A good correlation is observed between the experimental and numerical results for better validation. The best design parameters among all 16 specimens are identified for applying energy absorption applications in the automobile and aviation fields in real-time. [ABSTRACT FROM AUTHOR]

This paper discusses a research study to examine the behaviour of a circular thin-walled column subjected to quasi-static axial loading. Pure aluminium and hybrid aluminium/GFRP thin-walled column were experimentally tested, then a numerical simulation model using LS-Dyna approached the results. A parametric study was investigated with several material model parameters for a deeper understanding of the woven prepreg GFRP composite modelling. It was found that the failure mode and crashworthiness parameters result would be affected by parameter variations. Therefore, the values used for these parameters were obtained by doing parameter calibration so that the load-displacement response of the thin-walled column is similar to experimental results. The further parametric study result showed that the composite layers wrapped around the outer wall could increase the capacity of the energy absorption thin-walled column. Adding thickness to the composite layers would increase crashworthiness parameters, including mean crushing force, energy absorption, and specific energy absorption under quasi-static loading. Furthermore, the proposed modelling strategy developed in this work can be used as a reference for modelling the thin-walled column made of hybrid material due to the limited comprehensive numerical parametric studies on hybrid thin-walled column. [ABSTRACT FROM AUTHOR]

The evolution of plasticizing mechanism and mechanical properties of the Fe-11Mn-4Al-0. 2C medium-Mn steel during deformation were compared in this paper. With the increase of strain rate (0. 002~200 s-1), the trends of changes in yield strength and tensile strength for the medium-Mn steel are completely opposite. The yield strength increases from 507 MPa to 649 MPa, while the tensile strength decreases from 1 089 MPa to 876 MPa. The plasticizing mechanism of quasi‑static loading is dominated by the strong TRIP (transformation‑induced plasticity) effect. The plasticizing mechanism is dominated by the weak TRIP effect in the initial stage of dynamic loading, and the TRIP effect disappears and the plasticizing mechanism changes into the temperature rise softening effect and the TWIP (twinning‑induced plasticity) effect in the later stage of dynamic loading. The dislocation motion rate in the initial stage of dynamic loading is much higher than that of quasi‑static loading, which results in the higher yield strength of dynamic loading than that of quasi‑static loading. With the increase of strain, the cumulative adiabatic temperature rise inhibits the martensitic transformation and reduces the work‑hardening capacity under dynamic loading, while the high hardness martensite is produced continuously under quasi‑static loading, which results in the tensile strength of quasi‑static loading higher than that of dynamic loading. [ABSTRACT FROM AUTHOR]

Copyright of Industria Textila is the property of Institutul National de Cercetare-Dezvoltare pentru Textile si Pielarie 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 paper presents the process of conducting the structural analysis of AlAinSat-1 CubeSat through a numerical solution using Siemens NX. AlAinSat-1 is a 3U remote-sensing CubeSat carrying two earth observation payloads. The CubeSat is scheduled for launch on SpaceX Falcon 9 rocket. To ensure the success of the mission and its ability to withstand the launch environment, several scenarios should be analyzed. For AlAinSat-1 model the finite element analysis (FEA) method is used, and four types of structural analyses are considered: modal, quasi-static, buckling, and random vibration analyses. The workflow cycle includes idealizing, meshing, assembling, applying connections and boundary conditions, and eventually running the simulation utilizing the Siemens Nastran solver. The simulation results of all analysis types indicate that the model can safely withstand the loads exerted during launch. Also, the numerical results of the Command and Data Handling Subsystem (CDHS) module of AlAinSat-1 are experimentally validated through a vibration test conducted using an LV8 shaker system. The module successfully passed the test based on the test success criteria provided by the launcher. [ABSTRACT FROM AUTHOR]

Abstract This paper investigates sandwich beams with lattice cores under quasi-static bending, owing to their lightweight nature and high energy absorption capabilities. Utilizing analytical methods governing beams, an investigation into their failure mechanisms is conducted, incorporating experimental and numerical results. The influence of thickness and core cell sizes on energy absorption are examined. The analysis delves into the elastic and plastic behavior of the beam, which is refined and validated against the numerical and experimental tests and failure modes of sandwich panel beams. The alignment of analytical predictions with both experimental and numerical results in terms of mean forces, and energy absorptions was remarkably precise. Moreover, evidence has been presented that the face yield and core shear failure regions are significantly impacted by variances in core dimensions. Additionally, the thickness of core cell strands was found to be pivotal in influencing the compressive and shear strengths of sandwich panel beams.

The study investigates the effects of pore diameter, pore spacing, and arrangement on the energy absorption ability of closed-cell aluminum foam. The optimal arrangement of pores for energy absorption was determined using experimental design and the finite element method. Aluminum 6063 with a simple cubic structure was found to be the most efficient at energy absorption, while aluminum 356 with a simple cubic structure was the least effective. As the load rate increased, the effect of the parameter t exceeded that of h in both structures. The response surface method's proposed model was deemed effective, with the difference between experimental and predicted values around 15%–20%. [ABSTRACT FROM AUTHOR]

A seismic-induced landslide is a common geological catastrophe that occurs in nature. The Wangjiayan landslide, which was triggered by the Wenchuan earthquake, is a typical case in point. The Wanjiayan landslide caused many casualties and resulted in enormous property loss. This study constructs a simple surficial failure model based on the upper bound approach of three-dimensional (3D) limit analysis to evaluate the slope stability of the Wangjiayan case, while a traditional two-dimensional (2D) analysis is also conducted as a reference for comparison with the results of the 3D analysis. A quasi-static calculation is used to study the effect of the earthquake in terms of horizontal ground acceleration, while a parametric study is conducted to evaluate the critical cohesion of slopes. Rather than employing a 3D analysis, using the 2D analysis yields an underestimation regarding the safety factor. In the Wangjiayan landslide, the difference in the factors of safety between the 3D and 2D analyses can reach 20%. The sliding surface morphology as determined by the 3D method is similar to actual morphology, and the parameters of both are also compared to analyze the reliability of the proposed 3D method. [ABSTRACT FROM AUTHOR]

We explore the relationship between rough surface conductors and the phenomenon of passive intermodulation. The underlying surface is taken to be the boundary of a Lipschitz domain, and a characteristic angle of the domain is used to track boundary dependence on the various fields. To model electro‐thermal passive intermodulation in particular, we consider a specific type of temperature‐dependent conductivity and determine conditions on the conductivity under which one can use fixed point arguments to solve an induction heating and Joule heating problem on a Lipschitz domain. In the latter problem, we also consider a time‐dependent permittivity function ε$\varepsilon$. Finally, weak solutions to a magneto‐quasi‐static problem are obtained when the permeability µ is temperature dependent and is allowed to degenerate in a certain way. An interesting effect of the rough surface is the inherently limited Sobolev regularity of the electric field, which can be improved if one assumes additional constraints on the boundary. [ABSTRACT FROM AUTHOR]

This paper presents the first-ever investigation of Menger fractal cubes' quasi-static compression and impact behaviour. Menger cubes with different void ratios were 3D printed using polylactic acid (PLA) with dimensions of 40 mm x 40 mm x 40 mm. Three different orders of Menger cubes with different void ratios were considered, namely M1 with a void ratio of 0.26, M2 with a void ratio of 0.45, and M3 with a void ratio of 0.60. Quasi-static Compression tests were conducted using a universal testing machine, while the drop hammer was used to observe the behaviour under impact loading. The fracture mechanism, energy efficiency and force-time histories were studied. With the structured nature of the void formation and predictability of the failure modes, the Menger geometry showed some promise compared to other alternatives, such as foams and honeycombs. With the increasing void ratio, the Menger geometries show force-displacement behaviour similar to hyper-elastic materials such as rubber and polymers. The third-order Menger cubes showed the highest energy absorption efficiency compared to the other two geometries in this study. The findings of the present work reveal the possibility of using additively manufactured Menger geometries as an energy-efficient system capable of reducing the transmitting force in applications such as crash barriers. [ABSTRACT FROM AUTHOR]

In this paper, various sandwich panels with different face-sheet materials and three types of aluminum honeycomb cores are fabricated, the covers are made of either aluminum or glass fiber reinforced epoxy, and the panel's quasi-static behavior was examined using three tests; flexural, edgewise, and flatwise. The cores used in the panels have different properties according to cell sizes and heights. All manufactured panels have the same thickness. The results were presented as curves and tables so that the variables influencing the panel's durability could be determined. Results showed that flatwise compressive strength increased for specimens using covers made of aluminum material than fiberglass by about 40%. Samples that employed cores with smaller cell sizes showed more compressive strength in the flatwise direction than specimens using larger cells of cores by about 15%. While compressive strength in a direction that is parallel to the face sheet showed higher values for specimens of a fiberglass cover than aluminum material covers by about 14%. Flexural strength has decreased by samples using covers made of fiberglass than aluminum material by about (40 -- 90) % depending on the face-sheet thickness and cell size. Specimens with epoxy-filled cores showed the maximum compressive strength values in all cases. During flexural and edgewise tests, de-bonding failure has occurred commonly in samples using aluminum skins. [ABSTRACT FROM AUTHOR]

In the present research, glass and basalt fiber-reinforced polypropylene composites' behaviour in quasi-static and dynamic conditions is studied. Composites were fabricated by vacuum assisted Compression molding method. Composites failure under quasi-static tension and compressive conditions was studied along with its failure behaviour under low-velocity impact and super-sonic shock loading under dynamic conditions. The study results showed that basalt fiber-reinforced polypropylene (Basalt/PP) composite's tensile and compressive strength is higher than glass fiber-reinforced polypropylene (Glass/PP). The Basalt/PP showed no penetration against low velocity impact (LVI) with negligible deformations till 50 J. However, the Glass/PP perforated at 50 J with various failure patterns occurring at back side. The fiber-matrix interface adhesion plays an important role in super-sonic shock loading by absorbing shock wave energy due to ductile nature of polypropylene and the two composites absorbed energy via matrix and fibers failure, no brittle failure of laminates occurred under shock loading. [ABSTRACT FROM AUTHOR]

In this paper, the stress–strain curves of Ti2AlNb are established based on uniaxial impact tests over wide ranges of temperature and strain rate. The Ti2AlNb exhibited the work hardening effect but did not show an obvious yield stage during a quasi-static compression test. In the SHPB test, an obvious temperature softening effect was found, the strain rate strengthening effect was detected when the strain rate was 4000–8000 s−1, and the strain rate softening effect was detected in the range of 8000–12,000 s−1. A function describing the effect of strain rate on the strain rate strengthening parameters under various temperatures was proposed to modify the basic J-C constitutive model. The relative errors between the experimental measured value and predicted values in various experimental conditions with a modified J-C model were less than 5.0%. The results verified that the modified J-C model could accurately describe the dynamic mechanical properties of Ti2AlNb at high temperatures and strain rates. The research could help to illustrate the cutting mechanism and finite element simulation of Ti2AlNb alloy. [ABSTRACT FROM AUTHOR]

Abstract This study presents a thorough numerical evaluation of the crashworthiness properties of a new bio-inspired DNA tubes (BIDNATs) with circular, elliptical, and rectangular cross-sections. Deformation and crashworthiness behaviors are evaluated using axial quasi-static crushing simulations by ABAQUS/Explicit (Abaqus 6.14, https://www.3ds.com/products-services/simulia/products/abaqus/ ). The study compares the performance of conventional tubes with rectangular and elliptical cross-sections to DNA-inspired tubes. Increasing the rotation angle leads to more helices and a pronounced helix angle, resulting in lower initial peak force (IPF). However, lower cross-section aspect ratios generally have higher IPF and specific energy absorption (SEA) values. BIDNATs with rectangular cross-sections and a 540° rotation angle have the lowest SEA and IPF values across all aspect ratios. Notably, for the 110/100 aspect ratio, the SEA of E110/100 is 71% higher than the conventional tube. Overall, BIDNATs with elliptical cross-sections and a 360° rotation angle exhibit higher SEA values and lower IPF values, particularly for a width (W) of 100 mm. Conventional circular and elliptical tubes generally have SEA values exceeding 6 J/g, with only E110/100 surpassing this among DNA-inspired tubes. The NE110/100 tube has the highest SEA, surpassing E110/100 by 54%, while its IPF is 10% greater than DNA-inspired E110/100. It's worth noting that conventional circular and elliptical tubes have higher IPF values compared to their DNA-inspired counterparts. These findings offer valuable insights for engineers and researchers in the design of crash tubes to improve overall vehicle safety for both occupants and pedestrians.

In this article, the experimental and finite element analysis is utilized to investigate the quasi-static compression features of sandwich constructions built with tapered tubes. 3D printing technology was utilized to create the hollow centers of the tapering tubes, with and without corrugations. The results demonstrate that the energy absorption (EA) and specific energy absorption (SEA) of the single corrugated tapered tube sandwich are 51.6% and 19.8% higher, respectively, than those of the conical tube sandwich. Furthermore, the results demonstrate that energy absorbers can benefit from corrugation in order to increase their efficiency. Additionally, the tapered corrugated tubes’ resistance to oblique impacts was studied. Compared to a straight tube, the tapered tube is more resistant to oblique loads and has a lower initial peak crushing force (PCF), according to numerical simulations. After conducting a parametric study, it was discovered that the energy absorption performance of the sandwich construction is significantly affected by the amplitude, number of corrugations, and wall thickness. EA and SEA of DTS with corrugation number of 8 increased by 17.4% and 29.6%, respectively, while PCF decreased by 9.2% compared to DTS with corrugation number of 10.

The electrode tabs of pouch cells are rigidly joined to the bus bar in a battery module to achieve an electric connection. The effect of abusive mechanical loads arising from crash-related deformation or the possible movement of battery cells caused by operation-dependent thickness variations has so far never been investigated. Three quasi-static abuse tests for the anode and cathode electrode tabs were conducted with pouch cells at 100% SOC. Tensile tests on the anode, cathode and pouch foil were performed in order to explain differences between the anode and cathode in the abuse tests. The experiments revealed different failure mechanisms for the anode and cathode electrode tabs. The cathode failed at an average maximum load of 940.3 N through an external rupture of the electrode tab. The anode failed at an average maximum load of 868.9 N through a rupture of the single electrode sheets and the opening of the pouch foil. No thermal runaway occurred for either cathode or anode. The results of this study reveal a more critical failure behavior for the anode electrode tab, which can be addressed in the future by adding a predetermined breaking point and adapting the geometry of the anode electrode tab.

This research aims to experimentally investigate the energy absorption of thin-walled lattice tubes with a square section. The walls of the thin-walled tube are made in the form of a lattice with three types of cells: re-entrant auxetic, semi-re-entrant, and conventional honeycomb structures, and the material of the specimens is considered 304 stainless steels. All three types of lattice cells are produced by the rotary laser cutting method on a conventional tube and are axially compressed by a universal test machine under quasi-static loading at a 5 mm/min velocity. The test evaluation parameters are initial maximum force, mean crushing force, crushing force efficiency, energy absorption, and specific energy absorption. The results show that the thin-walled tube with the re-entrant auxetic structure has more specific energy absorption than the other two structures. The specific energy absorption of this structure is 25% higher than the conventional honeycomb structure. The semi-re-entrant structure has more energy absorption and mean crushing force than the other structures. The crushing force efficiency in the conventional honeycomb structure is higher than that of the other two structures, which has a value of 85%. [ABSTRACT FROM AUTHOR]

In most biomedical devices, such as fracture fixation devices and medical tools, the printed part is subjected to complex loadings that involve large deflections instead of large strains. Among various FDM tool path parameters, the fill pattern has a critical role in controlling voids and raster bonding. This work highlights the flexural performance of the PLA-printed part based on various fill patterns, such as concentric, linear, Hilbert, raster angle 45º, alternate pattern (0º/45º), and concentric pattern with holes resembling bone plate. Based on deposition paths, the dimensional changes and interlayer adhesion were analyzed before and after annealing. The flexural performance was evaluated using quasi-static three-point and four-point bend tests and dynamic flexural tests under temperature sweep. The annealed samples exhibit improved flexural strength regardless of infill pattern and loading conditions, with the concentric pattern showing better performance in both static and dynamic tests. [ABSTRACT FROM AUTHOR]

This study presents a thorough numerical evaluation of the crashworthiness properties of a new bio-inspired DNA tubes (BIDNATs) with circular, elliptical, and rectangular cross-sections. Deformation and crashworthiness behaviors are evaluated using axial quasi-static crushing simulations by ABAQUS/Explicit (Abaqus 6.14, https://www.3ds.com/products-services/simulia/products/abaqus/). The study compares the performance of conventional tubes with rectangular and elliptical cross-sections to DNA-inspired tubes. Increasing the rotation angle leads to more helices and a pronounced helix angle, resulting in lower initial peak force (IPF). However, lower cross-section aspect ratios generally have higher IPF and specific energy absorption (SEA) values. BIDNATs with rectangular cross-sections and a 540° rotation angle have the lowest SEA and IPF values across all aspect ratios. Notably, for the 110/100 aspect ratio, the SEA of E110/100 is 71% higher than the conventional tube. Overall, BIDNATs with elliptical cross-sections and a 360° rotation angle exhibit higher SEA values and lower IPF values, particularly for a width (W) of 100 mm. Conventional circular and elliptical tubes generally have SEA values exceeding 6 J/g, with only E110/100 surpassing this among DNA-inspired tubes. The NE110/100 tube has the highest SEA, surpassing E110/100 by 54%, while its IPF is 10% greater than DNA-inspired E110/100. It's worth noting that conventional circular and elliptical tubes have higher IPF values compared to their DNA-inspired counterparts. These findings offer valuable insights for engineers and researchers in the design of crash tubes to improve overall vehicle safety for both occupants and pedestrians. [ABSTRACT FROM AUTHOR]

Based on potential theory, the three-dimensional quasi-static general solution for isotropic chemoelastic materials is presented in this work. Through the three-dimensional general solution, the Green's function for an isotropic chemoelastic material subjected to dynamic point loads is derived. This can serve as theoretical guidance for future engineering practices. Four functions constitute the expressions of the general solution that satisfy the harmonic functions and the quasi-static transport equation, respectively. The Green's function for an isotropic chemoelastic material subjected to dynamic point loads is derived by combining the general solution with the chemical balance boundary conditions at infinity. It can be expressed in terms of the error function and elementary functions. Finally, the numerical results are provided, as shown in the contours. These results can be used to analyze the variation law in the coupling fields of isotropic chemoelastic materials. The corresponding analysis can provide a theoretical basis for elucidating the mechanism of the chemoelastic coupling problem in further work. [ABSTRACT FROM AUTHOR]

The reconstruction of the spatial complex conductivity σ + j ω ε 0 ε r from complex valued impedance measurements forms the inverse problem of complex electrical impedance tomography or complex electrical capacitance tomography. Regularized Gauß-Newton schemes have been proposed for their solution. However, the necessary computation of the Jacobian is known to be computationally expensive, as standard techniques such as adjoint field methods require additional simulations. In this work, we show a more efficient way to computationally access the Jacobian matrix. In particular, the presented techniques do not require additional simulations, making the use of the Jacobian, free of additional computational costs. [ABSTRACT FROM AUTHOR]

This study investigates the elastoplastic deformation behaviour of a motorcycle frame under quasi-static mechanical loading. We present a novel test rig to analyse the mechanical integrity of a motorcycle frame under four different load configurations. These four load configurations reproduce longitudinal forces, lateral forces, torques and bending moments that act on the frame in normal operation as braking, acceleration or cornering. Additionally, the four load configurations represent loads that act on the frame in the most frequent crash scenarios in urban areas, such as a motorcycle's frontal or inclined collision against a car. We conducted three repetitions of each load configuration with a frame from a motorcycle, especially for the urban area. The compliance of the measured load–displacement curves is rated by an objective assessment method. All tested frames show a similar elastoplastic deformation pattern; specifically, the longitudinal tubes are pressed outside, and fractures occur predominantly at areas of welding spots while the inner part remains scarcely deformed. The load–displacement curves, mechanical failures, weak points and deformation behaviour of the frames can be used in future to validate a numerical model of a motorcycle frame and improve the crashworthiness of a motorcycle frame. Novel experiments on the elastoplastic characterisation of motorcycle frames Multidirection deformation and failure behaviour Motorcycle frame as protection for sensitive components such as batteries Approach to validate deformation patterns and mechanical resistance of simulation models Validation of the test reproducibility by compliance assessment of measurement data [ABSTRACT FROM AUTHOR]

IntroductionHallux valgus, a common foot deformity, often necessitates surgical intervention. This study evaluates the biomechanical alterations in patients post-surgery, focusing on the efficacy of an “8” bandage fixation system to promote optimal recovery.MethodsA three-dimensional (3D) model was constructed using CT data from a patient with hallux valgus. A quasi-static finite element analysis (FEA) was conducted in conjunction with gait analysis to evaluate the biomechanical changes at the osteotomy site under “8” shaped bandage fixation following hallux valgus surgery. The effects of the “8” shaped bandage on the stability of the osteotomy site and bone healing were investigated at three load points during the gait cycle.ResultsDuring the Loading Response (LR), Midstance (MSt), and Terminal stance TSt phases, the osteotomy end experienced maximum Von Mises stresses of 0.118, 1.349, and 1.485 MPa, respectively. Correspondingly, the maximum principal stresses, all of which were compressive along the Z-axis, were 0.11662 N, 1.39266 N, and 1.46762 N, respectively. Additionally, these phases showed a maximum relative total displacement of 0.848 mm and a maximum relative shear displacement of 0.872 mm.ConclusionDuring the stance phase, the osteotomy end of the first metatarsal is predominantly subjected to compressive stress, with the relative displacement within the safe range to promote healing. The application of an “8” bandage for external fixation after surgery can maintain the dynamic stability of osteotomy sites post-minimally invasive hallux valgus correction during the gait cycle, thereby promoting the healing of the osteotomy ends.

Crashworthiness is a passive device that has an important function as an absorbing component of the impact energy resulting from an accidental event. The main problem in the crashworthy design is the dimensional limitation on the front end of the vehicle with the driver so that most of the energy absorption is limited. Besides, the complexity of crashworthiness design is difficult to make conventionally. This research aims to find out the effectiveness of crashworthiness design in energy absorption and the resulting deformation patterns. Crashwortines are made in a multi-cell shape using PLA material and printed using a 3D printing raise machine. Crashworthiness is produced with four variation shapes of a Multi-cell circle (MCC), Multi-Cell square (MCS), Multicell pentagonal (MCP), and Multi-Cell pentagonal circles (MCPC) with a side thickness of 2 mm and a length of 150 mm. Experimental quasi-static testing is carried out in the frontal direction using a UTM machine at an operating speed of 2mm/s. The results of the study show that the design of the crash box of the pentagon circle has a significant increase in the energy absorption value of 62.49%, which can be recommended in future impact resistance tube designs. The characteristics of the deformation pattern and the failure resulting from the crashworthiness tend to form the pattern of the bending lamina failure. Failures can occur due to plastic fold, elastic bend, and pressure deformation mechanisms followed by new folding formations (lobes).

The study focuses on thermoelastic behavior of the time-fractional heat conduction equation in a thick hollow cylinder by quasi-static approach. The utilization of the Caputo fractional derivative has been employed. The upper and lower surfaces of the cylinder have been assigned arbitrary temperature values, while the boundaries of the cylinder remain at a constant temperature of zero. The integral transform technique has been utilized to solve the conduction equation. A mathematical model has been prepared for Copper material. The fractional-order thermoelasticity for distinct fractional values of time variable has been discussed and the results are presented graphically. [ABSTRACT FROM AUTHOR]

The enhancement of rollover stability in vehicles, particularly in liquid tank trucks, is imperative for reducing the risk of vehicular rollovers and consequent threats to human life and property. The dynamic behavior of the liquid within the tank during maneuvers such as turning or lane-changing plays a significant role in the vehicle's stability. It has been demonstrated that the implementation of a Proportional Integral Derivative (PID) controller within the stabilizer bar of an active suspension system can substantially mitigate the vehicle's propensity to roll. This mitigation is quantitatively evidenced by reductions in the lateral load transfer ratio (LTR) and the roll angle (TRA) of the suspension system. Specifically, during steady turning maneuvers, a decrease of 5.6% in LTR and 12.9% in TRA was observed for liquid levels deemed most hazardous at heights of 1.2m and 1.6m, respectively. Similarly, during lane-changing maneuvers, LTR was reduced by 6.2%, and TRA was decreased by 9.1% at critical liquid levels of 0.8m and 1.6m. These analytical outcomes were derived through the application of the Lagrange method and the quasi-static method for establishing the fluid vibration equation within the tank, supplemented by D'Alembert's principle in constructing a four Degrees of Freedom (DOFs) roll model for the differential equation system of vehicle motion. This research underpins the foundational principles for the design, manufacture, and enhancement of suspension systems, and elucidates the direction for future investigations into tank trucks transporting various liquid types. [ABSTRACT FROM AUTHOR]

In many crashworthiness protection conditions, materials with excellent energy absorption have been studied, and safety protection is more and more important. In this paper, several orthogonal trapezoidal aluminum honeycombs with different structures and morphologies were manufactured. Static tests and simulation analysis were carried out with different layers and sorting order and the effects were studied. Deformation mode and the influence of stress were analyzed to obtain a stable structure. The structure is intended to be used as a filling material for the impact limiter of the nuclear spent fuel transport cask. [ABSTRACT FROM AUTHOR]

Crashworthiness is a passive device that has an important function as an absorbing component of the impact energy resulting from an accidental event. The main problem in the crashworthy design is the dimensional limitation on the front end of the vehicle with the driver so that most of the energy absorption is limited. Besides, the complexity of crashworthiness design is difficult to make conventionally. This research aims to find out the effectiveness of crashworthiness design in energy absorption and the resulting deformation patterns. Crashwortines are made in a multi-cell shape using PLA material and printed using a 3D printing raise machine. Crashworthiness is produced with four variation shapes of a Multi-cell circle (MCC), Multi-Cell square (MCS), Multicell pentagonal (MCP), and Multi-Cell pentagonal circles (MCPC) with a side thickness of 2 mm and a length of 150 mm. Experimental quasi-static testing is carried out in the frontal direction using a UTM machine at an operating speed of 2mm/s. The results of the study show that the design of the crash box of the pentagon circle has a significant increase in the energy absorption value of 62.49%, which can be recommended in future impact resistance tube designs. The characteristics of the deformation pattern and the failure resulting from the crashworthiness tend to form the pattern of the bending lamina failure. Failures can occur due to plastic fold, elastic bend, and pressure deformation mechanisms followed by new folding formations (lobes). [ABSTRACT FROM AUTHOR]

The stress–strain state arising during dynamic tension of a homogeneous rectangular plate of an incompressible ideally rigid–plastic material, which obeys the Mises–Hencky criterion, is considered. The upper and lower bases are stress-free; longitudinal velocities are set at the ends. The possibility of deformation of the upper and lower sides of the plate is taken into account, which simulates neck formation and further development of the neck. A small geometric parameter is introduced: the ratio of the average thickness of the plate to its length along one of the directions. At different time intervals, the order of smallness of the dimensionless functions characterizing the dynamic stretching mode may be different with respect to the geometric parameter which determines the stretching mode. Two such characteristic modes are identified: one is associated with a sufficiently high rate of removal of the ends of the plate from each other, the second with acceleration. In the second case, an analysis is carried out using the method of asymptotic integration, which allows us to approximately find the parameters of the stress–strain state. [ABSTRACT FROM AUTHOR]

This study embarks on an exploration of the thermal deflection characteristics of finite hollow cylinders, employing the space-time fractional heat conduction equation within a quasi-static framework. Heat application is executed on the upper surface of the cylinder, whilst maintaining a zero-temperature condition on the remaining boundaries. Temperature distribution across the cylinder is determined using the integral transform technique, a method ensuring precision in the computation of thermal responses. The discourse on thermal deflection is grounded in the principles of fractional diffusion wave theory, a contemporary approach providing deeper insights into heat conduction dynamics. Numerical analyses are presented, illustrating transient and long-range interaction responses of the hollow cylinder under various diffusion scenarios, namely sub-diffusion, normal diffusion, and super-diffusion. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Signal Processing is the property of Journal of Signal Processing 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.)

In this paper, the coupled linear quasi-static theory of elasticity for materials with double porosity is considered in which the concepts of Darcy's law and volume fractions are proposed. The system of general governing equations is expressed in terms of the displacement vector field, the changes of the volume fractions of pores and fissures, and the changes of the fluid pressures in pores and fissures networks. By virtue of Green's identity, the uniqueness theorems of the basic internal and external boundary value problems (BVPs) are proved. The fundamental solution of the system of steady vibration equations in the theory under consideration is constructed. Then, the surface and volume potentials are constructed and their basic properties are given. Some useful singular integral operators are studied. Finally, on the basis of these results the existence theorems for classical solutions of the BVPs are proved by means of the potential method (boundary integral equation method) and the theory of singular integral equations. [ABSTRACT FROM AUTHOR]