Design Of Sandwich Structures Research Articles

Crashworthiness analysis and optimization of brain-coral-inspired multilayer sandwich structures under axial crushing

Inspired by brain corals and cuttlebone, this study employed 3D printing technology to fabricate a novel bio-inspired multilayer sandwich structure based on the Hilbert space-filling curve (named BHSS). The mechanical behavior and deformation process of the BHSS were compared through quasi-static axial crushing experiments and finite element (FE) simulations. The energy absorbing characteristics of the BHSS with different layers were compared through FE simulations, and the results indicated that the 4-layer BHSS displayed superior crashworthiness. Then, parametric studies were conducted to investigate the influence of layer-height gradient and wall-thickness gradient on the energy absorption performance and deformation modes of the BHSS. It was confirmed that the double gradient designs significantly reduced the initial peak force and improved the specific energy absorption of the BHSS. Finally, the multi-objectives optimization based on response surface method and the non-dominated sorting genetic algorithm (NSGA-II) was employed to optimize the geometric parameters of the BHSS, aiming at the optimal configuration for better crashworthiness. Compared to the original design structure, the SEA of the optimized knee point structure was increased by 21.8% and the IPF was reduced by 72.6%. These findings provided valuable guidelines for the brain-coral-inspired design of multilayer sandwich structures with superior energy-absorbing performance.

Three birds with one stone strategy: A tri-modal radiator based on the cooling-compensation-heating effect

Passive radiative using solar energy for energy gain is receiving increasing attention as a green and sustainable energy supply method. However, passive radiative designs of existing materials are usually static and unsuitable for dynamic seasonal and weather changes. Here, we explore an efficient design of a temperature-adaptive thermal management sandwich structure that integrates passive daytime radiative cooling/heating and temperature control of phase change materials. Compared with conventional passive radiators, the developed phase change material-enhanced radiative cooler/heater (PDHM) can be flipped to adjust thermal management performance according to seasonal and diurnal temperature changes. The radiative cooling layer (PDRC) has a high solar reflectance (95%) and a high infrared emissivity (97%). The phase change layer (PCM) acts as an effective compensation for temperature, causing the PDRC cooling power to rise and fall by 15 W·m−2 during daytime and nighttime. The radiative heating layer (PDRH) has a low infrared emissivity (75.6%) and a high solar absorptivity (85.7%). The final PDHM aerogel achieves 11 °C below ambient temperature and 25 °C above ambient temperature under direct sunlight in summer and winter, and it leads to an increase in the average nighttime temperatures of 2.1 °C and 1 °C in summer and winter, reducing the diurnal temperature difference. Thus, the temperature-adaptive PDHM shows great potential for passive radiative regulation, which can further extend the application of passive radiators.

Achieving high-efficiency electromagnetic wave absorption performance in a 3-layer hierarchical porous magneto-dielectric nanocomposite

Hierarchical porous structures along with micro- and nanoparticles of magneto-dielectric components in sandwich structure design have superior potential applications in the field of electromagnetic wave absorption, due to high active dissipation phenomena such as multiple scatterings and reflections between components, 3D network pores and layers, coupling interactions between each layer, promotion of interfacial polarization, and so on. The Sandwich-Structure absorber composed of hierarchical porous Bi2MoO6, Cu microparticles, and FeNi nanoparticles was effectively constructed with optimization in layer thickness and low filler loading percentage. The microwave absorption characteristics of absorber samples varied in thickness but all less than 1.6 mm in total thickness were thoroughly examined. The as-prepared sandwich structure displayed a unique microwave absorbing behavior due to the multiple-layer structure, the dielectric dissipation property of both Bi2MoO6, Cu microparticles and the magnetic dissipation feature of FeNi nanoparticles, as well as the complementary effect between particles and layers. Minimum reflection loss (RLmini) of −45.5 dB at 5.5 GHz is obtained with proper optimization of layer order and thickness in a resin base 3-layer absorber sample with Bi2MoO6 placed as a top layer with 0.4 mm thickness, FeNi placed as a middle layer with 0.5 mm thickness, and finally Cu placed as a bottom layer with 0.7 mm thickness. The results show that the as-prepared 3-layer nanocomposite sample has a high potential for usage in microwave absorption in the low-frequency band.

On thermal and strain-rate dependences of polymethacrylimide (PMI) foam materials

Polymethacrylimide (PMI) foams exhibit great potentials in engineering applications thanks to its outstanding lightweight and superior mechanical properties. However, the temperature and loading rate can greatly affect its mechanical behaviors, which are the key factors in analysis and design of the PMI foam structures for practical applications. Unfortunately, there is lack of fundamental data and constitutive models available concerning the elastic-plastic properties of the PMI foam in various stress states at different ambient temperatures and different strain rates. Therefore, this study aims to fill this knowledge gap by generating basic experimental data and providing a generic modeling solution for PMI foam materials and structures. To better reflect the actual service conditions in practice, different stress states are considered under different temperatures and strain rates. The cyclic loads are applied to characterize the actual mechanical responses of the PMI foam where the initial and subsequent yield surfaces were calibrated and analyzed. Following the experimental results, the elasticity, plasticity, viscosity and damage of the PMI foam are investigated thoroughly, especially for the initial and subsequent yielding behaviors. Further, the thermal and strain rate dependent constitutive models are established and calibrated based on the in-house experimental data for finite element (FE) modeling. A novel damage model is proposed to replicate the phenomenon of the stiffness degradation in compression. It is found that accurate predictions on the mechanical responses of PMI foam can be achieved under different temperatures and strain rates. This study is anticipated to provide fundamental experimental data and effective constitutive models of PMI foam for real engineering applications, such as lightweight design of sandwich structures under some harsh conditions.

Optimization of the potting design using an approach for load path optimized designs of sandwich structures

AbstractIn sandwich structures, mass can be reduced or mechanical properties increased if the challenging local load distribution can be improved. Through numerical optimizations, novel designs can be determined and investigated in physical and virtual tests. This paper presents an approach for load path-optimized design of sandwich structures and novel design concepts. The approach is applied to the design concept of honeycombs filled with potting compound. Due to the shown transferability to higher structural levels, it can be used as a basis for the design optimization of any sandwich structure.

Study on the Deformation Mode and Energy Absorption Characteristics of Protective Honeycomb Sandwich Structures Based on the Combined Design of Lotus Root Nodes and Leaf Stem Veins

Sandwich structures are often used as protective structures on ships. To further improve the energy-absorbing characteristics of traditional honeycomb sandwich structures, an energy-absorbing mechanism is proposed based on the gradient folding deformation of lotus root nodes and a leafy stem vein homogenizing load mechanism. A honeycomb sandwich structure is then designed that combines lotus root nodes and leafy stem veins. Four types of peak-nest structures, traditional cellular structure (TCS), lotus root honeycomb structure (LRHS), leaf vein honeycomb structure (LVHS), and lotus root vein combined honeycomb structure (LRVHS), were prepared using 3D printing technology. The deformation modes and energy absorption characteristics of the four honeycomb structures under quasistatic action were investigated using a combination of experimental and simulation methods. It was found that the coupling design improved the energy absorption in the structural platform region of the LRHS by 51.4% compared to that of the TCS due to its mechanical mechanism of helical twisting and deformation. The leaf vein design was found to enhance the peak stress of the structure, resulting in a 4.84% increase in the peak stress of the LVHS compared to that of the TCS. The effects of the number, thickness, and position of the leaf vein plates on the honeycomb structure were further explored. The greatest structural SEA effect of 1.28 J/g was observed when the number of leaf vein plates was four. The highest SEA of 1.36 J/g was achieved with a leaf vein plate thickness of 0.6 mm, representing a 7.3% improvement compared to that of the 0.2 mm thickness. These findings may provide valuable insights into the design of lightweight honeycomb sandwich structures with high specific energy absorption.

Rational design of bidirectional sandwich structure with etched aluminum and carbon cloth for high-performance lithium-sulfur batteries

Lithium-sulfur (Li–S) batteries are promising energy storage systems with low-cost, high-energy density and environment-friendly characteristics. Nevertheless, there are still some issues that need to be settled in practical applications, such as the migration and shuttle effect of polysulfides, the poor conductivity of sulfur, and serious volume expansions in the cycling process. To overcome these challenges, we herein assemble a bidirectional 3D sandwich structured Li–S battery with an etched porous Al current collector and a conductive carbon cloth (CC) interlayer. The sandwich structure endows the Li–S battery with a high reversible capacity, low-capacity decay, good coulombic efficiency. In addition, the battery presents a competitive energy density of 1000 Wh kg−1-S and 200 Wh kg−1-cathode with a mass loading of 1.0 mg cm−2 at 1 C. Due to the remarkable electrochemical performance, the sandwich structure provides a potential for large-scale industrial production of Li–S batteries.

Asymmetric metamaterial sandwich structure with NIM characteristics for THz imaging application

This study presented a unique, miniaturised asymmetric interconnected vertical stripe (IVS) design for terahertz (THz) frequency applications. Therefore, this research aimed to achieve a frequency response of 0 to 10 THz using a 5 × 5 µm2 Silicon (Si) substrate material. Meanwhile, various parametric examinations were conducted to investigate variations in the performance. For example, the unit cell selection process was carefully examined by using various design structures and modifying the structure by adding split gaps and connecting bars between vertical stripes. Furthermore, the proposed sandwich structure design was used to compute the absorbance and reflectance properties. All the analytical examinations were executed utilising the Computer Simulation Technology (CST) 2019 software. The introduced IVS metamaterial exhibits negative index behaviour and has a single resonance frequency of 5.23 THz with an acceptable magnitude of − 24.38 dB. Additionally, the quadruple-layer IVS structure exhibits optimised transmission coefficient behaviour between 3 and 6 THz and 7 to 9 THz, respectively. However, the magnitude of the transmission coefficient increased with the number of material layers. Besides that, the absorbance study shows that using a quadruple-layer structure obtains unique and promising results. Overall, the proposed asymmetric IVS metamaterial design achieves the required performance by using a compact structure rather than extending the dimensions of the design.

Asymmetric sandwiched nanofibrillated cellulose composites prepared by one-pot vacuum filtration for ultrahigh electromagnetic interference shielding

High-efficiency electromagnetic interference (EMI) shielding composite films (EMI shielding effectiveness (SE) value > 100 dB) with a small thickness are imminently desired for eliminating the serious electromagnetic wave pollution. Herein, asymmetric sandwiched silver-coated four-needle zinc oxide whisker/nanofibrillated cellulose/Ti3C2Tx (F-ZnO&Ag/NFC/Ti3C2Tx) composite films consisting of the loose F-ZnO&Ag sedimentary layer and compact upper Ti3C2Tx layer were successful fabricated by a facile one-pot vacuum filtration method in combination with gravity-induced delamination. Arising from the favorable electrical conductivity and unique asymmetric sandwich structure, electromagnetic waves can be trapped and dissipated in the F-ZnO&Ag skeletons and strongly multiply reflected between top Ti3C2Tx layer and bottom F-ZnO&Ag layers. Thereby, F-ZnO&Ag/NFC/Ti3C2Tx-30.4 exhibits the ultrahigh averaged EMI SET of 103.9 dB (the maximal value of 123.8 dB) at a low thickness of merely 209 μm, which is far superior to that of almost all the reported NFC composites at the similar thickness to date. In the real EMI shielding application test, composite films are confirmed to block signal transmission and switch off the toy car system. Such simple and high-efficiency asymmetric sandwich structure design makes a great progress towards preparing and adjusting thin EMI shielding composite films for the promising application prospects in advanced electronics and communication technology.

Quasi-static indentation responses of FMLs/2.5D woven carbon-fiber honeycomb sandwich structures under different structural parameters

Here, a new type of sandwich structure made of fiber metal laminates (FMLs) as facesheet and 2.5D woven carbon-fiber (CFRP) honeycomb as core was developed. The FMLs/CFRP honeycomb sandwich structures were subjected to quasi-static indentation tests to investigate the mechanical response with the variation of panel structure, honeycomb cell element size, honeycomb core wall thickness, and honeycomb core height. In addition to experiments, a finite element method (FEM) model was also created in ABAQUS/Explicit to analyze the damage mechanisms and failure modes of honeycomb sandwich structures under quasi-static indentation. Both the experimental and FEM simulation results revealed that the honeycomb sandwich structure underwent two different failure modes under quasi-static loading: localized damage dominated by indentation and global damage due to overall bending deformation. The combination of panel strength and honeycomb core strength determined the failure mode of the sandwich structure. Damage analysis of the honeycomb core showed that it mainly underwent fiber compression damage and matrix compression damage under quasi-static indentation. This study provides guidance to optimize the design of honeycomb sandwich structures.

Static and dynamic study of fiber-reinforced hemispherical stacked sandwich structure

Sandwich structures have garnered considerable attention due to their ability to meet the requirements of the aerospace and defense industry for impact resistance and lightweight performance. Unlike the plate or block construction investigated in previous studies, this present study proposes a new type of configuration known as the fiber-reinforced hemispherical stacked sandwich (FRHSS) structure. The fabrication of this FRHSS is achieved through the utilization of the Vacuum Assisted Resin Transfer Molding (VARTM) process and its response under quasi-static compression load is analyzed through both simulation and experiment. It is found that the internal configuration design effectively determines the direction of contraction in the hemispherical construction when it is subjected to quasi-static compression load. Furthermore, the impact resistance of the FRHSS against projectile penetration is also assessed. Through a comparison of simulation and experimental results, it becomes evident that the Chang-Chang failure criterion can successfully model the penetration process. Finally, the influence of internal configuration on the penetration resistance of the structure is studied by finite element method. The results show that the internal configuration plays an important role in the ballistic limiting velocity and ballistic performance of the construction. This study provides a valuable reference for the design of hemispherical sandwich structures.

Free vibration and sound radiation of ABH-type functionally graded sandwich plates under elastic boundary restraints

Based on the first-order shear deformation theory, the free vibration and sound radiation of ABH-type functionally graded sandwich plates (ABH-type FG sandwich plate) under elastic boundary restraints are studied. The displacement field of the plate is described as an improved form of double Fourier cosine series and several closed-form auxiliary polynomial functions. The dynamic equation is solved by using the Rayleigh-Ritz method. The accuracy of the present method is validated and the effects of thickness variation coefficients and elastic boundary restraints on the vibr-acoustic characteristics are discussed. The research can provide an idea for the design of sandwich structures.

Enhanced the impact resistance by gradient face-sheet design of a sandwich structure

Sandwich structure has been designed to reduce the impact damage of the stress waves. However, the existing work focuses on the optimization of sandwich cores while the face-sheet structure is seldom improved. Here, we used the impedance matching theory to design a negative gradient face-sheet sandwich structure with excellent stress wave attenuation performance. Owing to stress wave attenuation form a high impedance to a low one, the negative gradient face-sheet sandwich structure shows a low peak stress of 5.51 MPa, and the average transmission peak stress is 2.69 MPa. The gradient face-sheet structure changes the compressive deformation behavior; thus, the energy absorption performance of the negative gradient face-sheet sandwich structure increases to be 1311.8 kJ/m3 and the specific energy absorption reaches 1072 J/kg. Finite-element methods further demonstrate the overall sandwich structures can be enhanced through alleviating the failure of sandwich core by a gradient face-sheet structure. This work provides a paradigm for the design of sandwich structures with high energy absorption performance.

Strength design optimization of sandwich composite structures under heavy dynamic loads

Recent researches have witnessed an increased interest in the Rapid Runway Repair (RRR) methods to rehabilitate damages that may be caused by different incidents, such as: natural disasters of earthquakes, floods or man-made vandalism in civil wars. RRR is a strategic process for airport operations for civil and peace-making missions. The current RRR techniques like precast concrete slabs, metal mats, and fiberglass mats have different pros and cons. The current study numerically investigates CFRP sandwich composite structure for RRR usage, where its strength is maximized by design optimization to reach the possible carrying aircraft wheel capacity and safety factors. The proposed composite structure is advantageous of no corrosion, low erection time, high capacity-to-weight ratio, same finish of runway surface and repaired area, and can be applied over spots of unlevelled or inadequate bearing capacity of 60 cm diameter. The strength of the basic design of composite sandwich structure is first assessed to its maximum allowed carrying aircraft wheel capacity by FE modelling. Secondly, The Genetic Algorithm (GA) optimization technique is applied for maximizing the strength of the composite structure webs satisfying the minimum safety factor of five failure criteria of Tsai-Wu, Tsai-hill, Hoffman, Hashin and maximum stress. Finally, the achieved results promoted the usage of the composite structure to operate at the taxiways, runways, and theoretically, landing and take-off areas.

Theoretical Analysis of Plastic Behavior of Sandwich Beam with Metal Foam under Repeated Impacts

The phenomenon of repeated impacts on engineering structures is very common, especially in naval and ocean engineering. When marine structures are subjected to repeated impact loadings, deformation and damage will accumulate as the impact number increases, resulting in the failure and damage of the structures, even causing serious accidents. Based on the rigid-plastic assumption, a theoretical model is established to analyze the plastic mechanical behavior of metal foam sandwich beams (MFSBs) suffering from repeated impacts, in which the membrane factor method (MFM) is applied to derive analytical solutions for the plastic responses of MFSBs. The theoretical predictions agree well with the results of impact tests and numerical simulations, indicating that the theoretical model is accurate and reliable. In addition, the dynamic responses of MFSBs are analyzed based on the MFM, and the effects of the core strength and the face thickness on the deflection responses are determined. The results show that the dimensionless permanent deflection of MFSBs is sensitive to the core strength ratio and the face thickness ratio, and as the core strength ratio or the face thickness ratio increases, the dimensionless permanent deflection decreases gradually in an exponential form. In addition, the influence of the core strength ratio and face thickness ratio becomes more significant as the impact number increases. The proposed theoretical method can provide a theoretical reference and technical support for the design of metal foam sandwich structures with improved impact resistance under repeated impact loadings.

A novel explicit design method for complex thin-walled structures based on embedded solid moving morphable components

In this article, a novel explicit approach for designing complex thin-walled structures based on the Moving Morphable Component (MMC) method is proposed, which provides a unified framework to systematically address various design issues, including topology optimization, reinforced-rib layout optimization, and sandwich structure design problems. The complexity of thin-walled structures mainly comes from flexible geometries and the variation of thickness. On the one hand, the geometric complexity of thin-walled structures leads to the difficulty in automatically describing material distribution (e.g., reinforced ribs). On the other hand, thin-walled structures with different thicknesses require various hypotheses (e.g., Kirchhoff–Love shell theory and Reissner–Mindlin shell theory) to ensure the precision of structural responses. Whereas for cases that do not fit the shell hypothesis, the precision loss of response solutions is non-negligible in the optimization process since the accumulation of errors will cause entirely different designs. Hence, the current article proposes a novel embedded solid component to tackle these challenges. The geometric constraints that make the components fit to the curved thin-walled structure are whereby satisfied. Compared with traditional strategies, the proposed method is free from the limit of shell assumptions of structural analysis and can achieve optimized designs with clear load transmission paths at the cost of few design variables and degrees of freedom for finite element analysis (FEA). Finally, we apply the proposed method to several representative examples to demonstrate its effectiveness, efficiency, versatility, and potential to handle complex industrial structures.

Achieving excellent ferroelectric and dielectric performance of HfO2/ZrO2/HfO2 thin films under low operating voltage

Although the HfO2-based ferroelectric thin films are compatible with the complementary metal-oxide-semiconductor (CMOS) technology and exhibit excellent scalability, they still suffer from low dielectric tunability, metastable ferroelectric orthorhombic phase and poor endurance. Here, we fabricated the HfO2/ZrO2/HfO2 sandwich structured thin films via atomic layer deposition process as well as the influence of voltage cycling, Hf/Zr ratios and annealing temperature on ferroelectricity and dielectric tunability of them was investigated systematically. At pristine states, the antiferroelectric-like behavior of polarization-voltage hysteresis loops become more and more obvious with the decrement of ZrO2 content in the middle layers. After waking-up, the large remnant polarization (2Pr, ∼43 μC/cm2) and high dielectric tunability (∼51 %) can be achieved under low operating voltage of 2.5 V. Noting that the 2Pr is still higher than 40 μC/cm2 and the dielectric tunability remains about 50 % after 109 cycles. In addition, the HfO2/ZrO2/HfO2 thin films also exhibited high energy storage properties with the total energy storage density of ∼62 J/cm3 and the recoverable energy storage density of ∼32 J/cm3. These results indicated that the strategy of sandwich structure design is beneficial to promoting the development of electronic devices towards miniaturization, integrated, and multifunction along with high performance and reliability.

Design of smart sandwich structures enhanced by multi-functional shear thickening fluids (M−STFs): Anti-vibration and electrical conductivity

This study investigates a novel concept of integrating multi-functional shear thickening fluids (M−STFs) into the core layer of a sandwich composite consisting of polyvinyl chloride (PVC) foam and aluminum face sheets to enhance the vibration damping of the structure. First, high-performance STF (60 wt% SiO2) was produced and M−STFs were created by gradually adding multi-walled carbon nanotubes (MWCNTs) up to 1.5 wt%. The percolation threshold range was obtained and the effects of increasing MWCNTs up to 1.5 wt% to STF on reducing electrical resistance and improving rheological properties were investigated. Secondly, sandwich structures consisting of aluminum face sheets and PVC foam core layers were made. The smart nanofluids STF and M−STFs were added to sandwich structures through the grooves created in the PVC foam core. Six different configurations were designed to investigate the effects of adding STF and M−STFs on the vibration damping performance of the sandwich structures. The model analysis results showed that the M−STFs integration into the core layer of designed sandwich structures significantly enhances the damping ratio of the structures as well as provides a higher stiffness coefficient. It was observed that the sandwich structure filled with 1.0 wt% MWCNT exhibits the highest damping ratio and stiffness.

Revealing the Sound Transmission Loss Capacities of Sandwich Metamaterials with Re-Entrant Negative Poisson's Ratio Configuration.

Due to the influence of mass law, traditional lightweight sandwich structures have struggled to surpass solid structures in sound insulation performance. To this end, we propose an acoustic metamaterial structure with a sandwich configuration based on the re-entrant negative Poisson's ratio (NPR) structure and systematically investigate its sound transmission loss (STL) performance under incident plane wave conditions. We used the acoustic impedance tube method to experimentally study the sound insulation performance of the re-entrant NPR sandwich structure under free boundary conditions, and then established an acoustic analysis simulation model based on COMSOL Multiphysics software, which verified that the results obtained by the experiment and the numerical simulation were in good agreement. The results show that the sandwich structure exhibits excellent sound transmission loss performance in the studied frequency range (250-4000 Hz), and the overall sound insulation performance exceeds the curve of the mass theorem, basically achieving more than 20 dB when the sandwich thickness is 2 cm. Finally, we conduct parametric studies to establish a correlation between the geometric design of NPR sandwich structures and their sound transmission loss performance. The research shows that the changes of the length of the ribs, the distance from the ribs to the center of the unit, and the length of the upper wall and the lower wall have a significant impact on the sound insulation performance of the re-entrant NPR sandwich structure, while the change of the wall thickness basically will not affect the sound insulation performance of the sandwich structure. This research can provide practical ideas for the engineering application of noise suppression designs of lightweight structures.

Free vibration properties of beetle elytron plate: Composite material, stacked structure and boundary conditions

Beetle elytron plate (BEP), which is derived from the bionics of Trypoxylus dichotomus's elytra, is a typical lightweight and high-strength structure with superior and comprehensive mechanical properties. To promote the engineering application of BEPs, this paper explores the vibration characteristics of foam-filled fiber composite BEPs. Through the finite element method (FEM), structural parameters such as the length-to-width ratio, core height-to-thickness ratio, skin thickness and foam density influence the natural frequency and mode. Furthermore, the influence pattern of parameters (such as boundary conditions and the number of stacked layers) toward the first two orders of natural frequencies and modes of the BEP were investigated under controlled total height and controlled single layer height. The results indicate that 1) the ranking of structural parameters on the 1st order frequency from a strong to weak sequence is as follows: length-to-width ratio, core height-to-thickness ratio, foam density and skin thickness; for the 2nd order natural frequency: length-to-width ratio, skin thickness, foam density and core height-to-thickness ratio. 2) Generally, an increase in the length-to-width ratio will reduce the frequency of the BEP, and increases in the core height-to-thickness ratio and skin thickness will raise its frequency. Additionally, foam filling plays a decisive role in local deformation. 3) When the total height of the sandwich plate is controlled, the improvement of the boundary conditions can effectively boost its 2nd-order frequency (approximately 200%), but the 1st-order frequency can be significantly increased (approximately 140%) only when all four sides are improved. 4) In the case of controlling the height of the single layer of the sandwich plate, its frequency gradually increases with the increase in the number of stacked layers. However, when the constraints are weak or there are few stacked layers, increasing the number of stacked layers can effectively boost the vibration frequency. This paper provides references and suggestions for the design and application of sandwich structures, enriching the research on the mechanical properties of BEPs and establishing groundwork for promoting BEPs in engineering practices.