Mechanical Behavior Research Articles

Mechanical Behavior of Origami-Based Inflatable Bistable Foldable Panels

Abstract Deployable structures are extensively used in engineering. A bistable panel structure, inspired by multistable origami, is proposed, capable of deployment and folding powered by air pressure. Prototypes were manufactured using planar laser etching technology based on geometric design. Mechanical behavior under out-of-plane compression, in-plane compression, and out-of-plane bending loads was analyzed through experiments. The foldable panel showed superior mechanical performance under out-of-plane compression, highlighting its potential as an ideal energy-absorbing material. In-plane compression and out-of-plane bending along the folding direction exhibited lower strength due to foldability, with failure modes involving rigidity loss from folding. The structure demonstrated good energy absorption characteristics during in-plane compression. As the angle of the unit increased during out-of-plane bending, mechanical performance improved, but the failure mode shifted to fracture. In in-plane compression and out-of-plane bending perpendicular to the folding direction, mechanical performance was enhanced, but the structure failed due to strength loss from fracture.

Numerical Study of Cone Penetration Tests in Lunar Regolith for Strength Index

The cohesive properties of lunar regolith, combined with a low-gravity environment, result in it having a distinct mechanical behavior from sandy soil on Earth. Consequently, empirical formulas derived from cone penetration tests (CPTs) for calculating the shear strength parameters of Earth’s sand cannot be directly applied to lunar regolith. This study utilized the three-dimensional discrete element method (DEM) to numerically simulate triaxial shear tests and cone penetration tests in a lunar environment. The particle contact model for lunar regolith in the discrete element method (DEM) simulation incorporated the hysteresis effect of van der Waals forces, thereby simulating the cohesive properties of lunar regolith in a lunar environment. We proposed a relationship for calculating the shear strength index of lunar regolith based on normalized cone tip resistance using the results from triaxial and CPT simulations and referencing empirical formulas derived from ground-based CPT data. The results of this study provide a valuable reference for future lunar CPTs.

Residual textile reinforced mortar‐to‐concrete bond after exposure to harsh environments

AbstractTextile reinforced mortars (TRM) are materials whose mechanical behavior has been extensively investigated during the last few years. However, studies on the behavior of these materials after exposure to various aggressive environments are still limited and, hence, their performance during their entire service life remains to be determined. The present study contributes to the knowledge pool regarding the behavior of concrete specimens furnished with TRM overlays post their exposure to various harsh environments, specifically through the analysis of shear bond tests. More specifically, 120 concrete substrates were reinforced with one and two layers of carbon textile which were embedded into a high and a low strength cementitious mortar and exposed to various harsh environments (carbonation, chlorides, carbonation and chlorides, different number of freeze–thaw cycles). It was concluded that: (i) a reduction of more than 25% is possible regarding failure stress; (ii) the number of textile layers plays an important role in TRM‐concrete bond behavior; and (iii) the influence of mortar strength is limited.

Response Surface Methodology Approach for the Prediction and Optimization of the Mechanical Properties of Sustainable Laterized Concrete Incorporating Eco-Friendly Calcium Carbide Waste

This study investigated the combined effects of calcium carbide waste (CCW) and lateritic soil (LS) on sustainable concrete’s fresh and mechanical properties as a construction material for infrastructure development. The study will explore the possibility of using easily accessible materials, such as lateritic soils and calcium carbide waste. Therefore, laterite soil was used to replace some portions of fine aggregate at 0% to 40% (interval of 10%) by weight, while CCW substituted the cement content at 0%, 5%, 10%, 15%, and 20% by weight. A response surface methodology/central composite design (RSM/CCD) tool was applied to design and develop statistical models for predicting and optimizing the properties of the sustainable concrete. The LS and CCW were input variables, and compressive strength and splitting tensile properties are response variables. The results indicated that the combined effects of CCW and LS improve workability by 18.2% compared to the control mixture. Regarding the mechanical properties, the synergic effects of CCW as a cementitious material and LS as a fine aggregate have improved the concrete’s compressive and splitting tensile strengths. The contribution of LS is more pronounced than that of CCW. The established models have successfully predicted the mechanical behavior and fresh properties of sustainable concrete utilizing LS and CCW as the independent variables with high accuracy. The optimized responses can be achieved with 15% CCW and 10% lateritic soil as a substitute for fine aggregate weight. These optimization outcomes produced the most robust possible results, with a desirability of 81.3%.

Fast parameter optimization for high-fidelity crystal plasticity simulation using active learning

Crystal plasticity (CP) simulation is a powerful tool for studying and understanding the mechanical behavior of materials. A critical aspect of this method is the accurate determination of CP parameters, which ensures that the constitutive model accurately represents the real deformation behavior of a material, especially in high-fidelity simulations. However, identifying these parameters poses a significant challenge due to the high computational cost and the difficulty of finding optimal solutions within a vast and complex parameter space. To address these challenges, we propose a fast search strategy that leverages active learning (AL) and experimental data to accelerate the optimization of CP parameters. Using the Al-Cu eutectic materials as a case study, we introduced a quantitative index, C ecp, to measure the consistency between simulated and experimental stress-strain curves. We demonstrated that Gaussian process regression (GPR) serves as the most appropriate surrogate model for relating CP parameters and C ecp based on our dataset. After only six iterations guided by AL, the optimal CP parameters were successfully identified, resulting in a high-fidelity CP model for analyzing the mechanical behavior of Al-Cu eutectic materials. The machine learning-enhanced strategy is far superior to traditional methods in terms of both efficiency and accuracy. It advances our understanding of the macro-micro relationships of materials and accelerates the material design process.

Damage Characteristics and Mechanical Properties of DD6 Single‐Crystal Alloy Based on Crystal Plasticity Theory under Uniaxial Tensile Conditions

Herein, the mechanical behavior and damage characteristics of DD6 nickel‐based single crystal alloy under different crystal orientation conditions are studied based on the theory of crystal plasticity coupled with damage constitutive equations using the crystal plasticity finite‐element method. The results indicate that the crystal plastic finite‐element model coupled with damage constitutive equations can well describe the entire deformation process from elasticity to damage. Under the reference orientation condition, the damage starts from the center position inside the test specimen and extends to the surrounding areas. The stress value in the damaged area decreases gradually from the periphery to the center of the test specimen, and an external stress reduction zone is formed. The crystal exhibits the best elasticity properties in the [0, 1, 1] orientation and the best plasticity properties in the [0, tan22.5°, 1] orientation. As the rotation angle of crystal orientation increases, the damage zones of X‐Z, Z‐Y, and X‐Y sections all exhibit clockwise rotation characteristics.

Characterization of Long‐Term Municipal Solid Waste Constitutive Behavior With Coupled Biodegradation and Fibrous Reinforcing Effects

ABSTRACTTo appropriately simulate the long‐term mechanical behavior of municipal solid waste (MSW), a constitutive model coupling the effects of biodegradation and fibrous reinforcement was developed. In the proposed model, the compressive deformation due to biodegradation was regarded as being caused by an additional equivalent stress. Considering the effect of biodegradation, an evolution equation of the equivalent stress was proposed, and a plastic volumetric strain hardening law was developed. A fibrous reinforcement parameter was introduced, which was associated with the fiber content, stress state, and plastic shear strain of MSW. A plastic shear strain hardening law was developed to model the fibrous reinforcement. Based on the associated flow rule and two plastic strain hardening laws, the proposed model was established. The proposed model well simulated the hardening properties of MSW, as evidenced by the stress‒strain curves and the consistent, nonlinear increase in volumetric strain with axial strain. The differences in the shear strength and volumetric deformation due to the confining stress and fiber content were also well simulated by the model. Furthermore, the model predictions accurately reflected the findings of experiments conducted over a period of 10 years. Finally, parametric investigations were used to calibrate this proposed model, which can well characterize the long‐term MSW mechanical behavior.

Magnesium Alloy and Silicon Nitrides Composite Study: Synthesis and Abrasive Water Jet Machining Behavior and Optimization

<div>Related to traditional engineering materials, magnesium alloy-based composites have the potential for automobile applications and exhibit superior specific mechanical behavior. This study aims to synthesize the magnesium alloy (AZ61) composite configured with 0 wt%, 4 wt%, 8 wt%, and 12 wt% of silicon nitride micron particles, developed through a two-step stir-casting process under an argon environment. The synthesized cast AZ61 alloy matrix and its alloy embedded with 4 wt%, 8 wt%, and 12 wt% of Si<sub>3</sub>N<sub>4</sub> are subjected to an abrasive water jet drilling/machining (AJWM) process under varied input sources such as the diameter of the drill (D), transverse speed rate (v), and composition of AZ61 composite sample. Influences of AJWM input sources on metal removal rate (MRR) and surface roughness (Ra) are calculated for identifying the optimum input source factors to attain the best output responses like maximum MRR and minimum Ra via analysis of variant (ANOVA) Taguchi route with L16 design approach. The ANOVA analysis revealed that D, v and the composition of AZ61 alloy composite contribute 26.45%, 16.28%, and 20.84%, respectively, to the output response conditions for higher MRR. Additionally, design 7 exhibits a high MRR of 0.017 g/s and a surface roughness (Ra) of 0.84 μm. The optimum AWJM input source of design 7 is proposed for industries to mass production applications.</div>

Recent developments in the mechanical properties and recycling of fiber‐reinforced polymer composites

AbstractFiber‐reinforced polymer composites (FRPCs) have become integral to various industries due to their exceptional strength‐to‐weight ratio, corrosion resistance, and versatility. Recent advancements in the properties and recycling of FRPCs reflect significant progress in performance and sustainability. This paper reviews the latest developments in FRPC technology, highlighting innovations in material formulation, including advancements in fiber types, matrix materials, and hybrid composites that enhance mechanical properties. Furthermore, this review emphasizes the modification of matrices by incorporating graphene, which aims to improve the chemical bonding and mechanical interlocking between fiber and matrix. Additionally, it addresses recent breakthroughs in recycling technologies, focusing on methods such as chemical recycling, mechanical recycling, and developing eco‐friendly matrices. Integrating these advancements aims to improve the lifecycle management of FRPCs, reduce environmental impact, and support the transition towards a circular economy. This review underscores the balance between enhancing composite performance and promoting sustainable practices, paving the way for more environmentally responsible applications of FRPCs.Highlights The different types of fiber‐reinforced polymer composites have been thoroughly reviewed. How does graphene affect the mechanical behavior of fiber composite laminates? Provide a systematic correlation and comparison between fabrication methods, materials, and properties. The recycling methods for fiber‐reinforced polymer composites have been deliberated.

Mechanical Behaviour Assessment and Optimization of Construction Sequence for an HSS Vierendeel Truss

Long-span Vierendeel trusses in construction are challenged by smooth force transfer and critical stress control concerns. In this article, construction sequences characterized by loading/unloading due to various assemblies of the branches and/or temporary lattice column supports are focused on to reproduce their related mechanical behaviours in finite element modelling. Typical bending moment and shear force diagrams for hollow structure section (HSS) chords are analysed first, and then combined with a corrected assessment index in the development of an optimized construction scheme through effective discussion. It is observed that the branch assembly sequence has significant but reversed influences on either the bending moments or the shear forces of the interior support and the midspan of the HSS chords. The influence of the branch assembly sequence on the bending moment and shear force are compromised with the introduction of a temporary support. The corrected assessment index superimposed by the internal force and the deflection is demonstrated properly to represent the strength and the serviceability requirements, especially for characterizing the removal of a temporary support after the completed construction of a twelve-panel Vierendeel truss for the roof of an assembly hall.

An Analysis of Dynamic Recrystallization During the Reduction Pretreatment Process Using a Multiscale Model

In this study, a multiscale model is developed through secondary development (UMAT and UEXTERNALDB) in Abaqus with the objective of simulating the thermal deformation process with dynamic recrystallization behavior. The model couples the finite element method (FEM) with the multiphase field model (MPFM), thereby establishing bidirectional coupling between macroscopic mechanical behavior and microstructural evolution. A comparison between the single-element hot compression simulation and experimental results demonstrates that the model accurately simulates both the macroscopic mechanical behavior and microstructural evolution during the thermal deformation process, thereby exhibiting high precision. Simulations of the reduction pretreatment (RP) process under different reduction amounts and billet surface temperatures demonstrate that increasing the reduction amount and billet surface temperature significantly enhances both plastic deformation and the volume fraction of dynamic recrystallization in the billet core. This results in the closure of core voids and the refinement of the core microstructure, thereby providing valuable guidance for the development of optimal reduction pretreatment (RP) processes.

Mechanical behaviour of pineapple leaf fibers reinforced Lapox L-12 epoxy composites

To meet the increasing need for composites in sectors such as medical, transportation, safety, and athletics, researchers continuously develop novel composites. This study investigated the effects of boron carbide filler particles in epoxy by fabricating composites from Lapox L-12 epoxy with 20 and 30 wt. % of pineapple leaf fibres (PALF) utilising the hand layup method. The mechanical parameters of the synthesised composites were evaluated according to ASTM standards, encompassing hardness, ultimate tensile strength, yield strength, elongation, and flexural strength. The addition of pineapple leaf fibres to epoxy Lapox L-12 resulted in enhanced hardness, tensile strength, and flexural strength, accompanied by a minor reduction in percentage elongation. Lapox L-12 composites supplemented with 30 wt.% of PALF exhibited enhancements of 60.8% in hardness, 66.2% in ultimate strength, and 101% in flexural strength.

Mechanical Behavior of Masonry Mortars Reinforced with Disposable Face Mask Strips

Mechanical Behavior of Masonry Mortars Reinforced with Disposable Face Mask Strips

Characterizing the interaction effects of modular components on transtibial prosthesis stance-phase mechanical behavior

Background: Despite evidence that passive prosthesis mechanical properties can directly affect user experience, prosthetists have access to minimal information regarding the mechanical interactions between a prosthetic foot and proximal modular componentry. Objectives: This study quantified the stance phase mechanical behavior of a transtibial prosthetic system through the addition of passive modular componentry to a dynamic response (DR) foot. Study Design: Repeated measures, mechanical characterization. Methods: Maximum displacement and energy return were measured with a materials test machine simulating initial, mid, and terminal stances. Twelve conditions were tested: a DR foot in combination with a hydraulic ankle at 2 resistance settings and 3 different shock-absorbing pylons (SAPs). The roll-over shape of the DR foot with and without hydraulic ankle was measured using a test rig. Results: Adding modular passive components altered displacement and energy return, displaying independent and interaction effects. Generally, the hydraulic ankle and SAP reduced energy return (up to 18%) but decreased (up to 51%) and increased (up to 88%) displacement, respectively, while the combined properties were more complex. Roll-over shape radii decreased with increasing load for the foot alone but exhibited a nonlinear response with the addition of the ankle. Conclusions: Inclusion of modular components in a transtibial prosthetic system can have complex mechanical interactions that independently affect the system's response to load. It is important for clinicians to be aware of the cumulative effects of these interactions to inform the tuning of transtibial prosthesis mechanical behavior. Combinations of hydraulic ankles and SAPs can help clinicians adjust the prosthesis to achieve a balance between user comfort and energy return.

Fabrication of Hydroxyl Modified Hollow Glass Microsphere Composite Isocyanate‐Based Polyimide Foam and Optimization Strategy Based on Different Bonding Mechanisms

ABSTRACTIn this study, the hydroxyl modified hollow glass microsphere (HM‐HGM) is added to different foaming slurries of isocyanate‐based polyimide foam (IBPIF) at varying ratios, and different bonding effects are formed to optimize the dispersion behavior. Then, the novel HGM composited IBPIF (IBPIF/HGM) is prepared. Hydroxyl groups on HM‐HGM establish hydrogen bonding effect with pyromellitic acid dimethyl ester and dimethyl formamide in the white slurry and react with isocyanate groups in the black slurry. The cell structure of IBPIF is altered to improve its sound absorption performance and mechanical behaviors. Compared with IBPIF/HGM‐0, the average cell size of IBPIF/HGM‐1 and BPIF/HGM‐5 decreases significantly. The sound absorption performance and mechanical behaviors of them are improved to some extent. Compared with samples in which the HM‐HGM is added alone to a single slurry, when the dosage ratio of HM‐HGM in black and white slurries is 1:1, IBPIF/HGM‐3 has more uniform cell structure. The change of IBPIF cell structure by the introduction of HM‐HGM and the unique structure of HM‐HGM can enhance the sound absorption performance and mechanical behaviors of IBPIF. The design idea of different bonding mechanisms significantly provides technical assistance to enhance the acoustic performance of polymeric foam materials.

Investigation on the mechanical and environmental behaviour of 3D-printed molds for manufacturing of CFRP components

Investigation on the mechanical and environmental behaviour of 3D-printed molds for manufacturing of CFRP components

Alginate/Chitosan Complex Fibers Reinforcement and Their Mechanical Transition Continuum With Water Uptake Increasing.

Living tissues span a remarkable spectrum of modulus ranging from the level of Pa to GPa in a water-rich environment. Constructing soft and hard materials that match the mechanics of tissues and researching mechanical transition in water, are beneficial for their biological applications. Here, using polyelectrolyte complex fiber as a model system and reinforcing the fiber by stepwisely introducing additional coordination and covalent bonds, this investigated that the water effect on mechanical transition behaviors. Alginate/chitosan fiber (AC fiber) has a single electrostatic bond and shows continuous mechanical transition containing a glassy state, rubbery state, and terminal relaxation (initial modulus lower than 10MPa) in aqueous solution. Alginate/chitosan/calcium fiber (ACC fiber) has both electrostatic and coordination bonds, which shows the behavior of hard rubber (initial modulus 100MPa) when water reaches equilibrium. Alginate/chitosan/calcium/polydopamine fiber (ACCP fiber) with triple bonds, including electrostatic, coordination, and covalent bonds, exhibits the behavior like ductile plastics in aqueous solution (initial modulus 1000MPa). This work not only provides important insight into the toughening mechanism of polyelectrolyte complexes in water but also contributes to the preparation of tissue adaptive implantations.

Influence of flow discharge and minibasin shape on the flow behavior and depositional mechanics of ponded turbidity currents

The interplay between seafloor sediment-laden density-driven flows, turbidity currents, and topography helps to shape continental margins. However, these interactions are poorly understood, especially those within enclosed depressions termed minibasins. In this study, novel experiments quantify the three-dimensional (3-D) dynamics of turbidity currents interacting with a range of minibasin geometries that, for the first time, scale within the parameter space of natural systems. Controls on flow dynamics are quantified by measuring the evolving velocity and sediment transport fields, in addition to maps of bathymetry. This study focuses on three aspects of turbidity current interactions with minibasins. First, the results suggest that sediment transport and deposition in minibasins is likely dominated by evolving flow conditions. Contrary to earlier studies in two-dimensional (2-D) flumes, this study supports a time-to-flow equilibrium in minibasins that scales with the time to replace ambient fluid with turbid influx, and this replacement time likely takes days to achieve in many field-scale minibasins. Second, in all experiments, horizontal flow circulation is observed, which is critical for distributing sediment throughout minibasins. However, the strength of the horizontal circulation reduces as the ratio of minibasin length to width increases, which leads to stagnant or even upstream-directed flow near the bed, elevated height of the velocity maximum in flows, the lowering of near-bed shear stresses, and more homogeneous deposits through a reduction in bed reworking. Finally, the results indicate that fluid detrainment from minibasins significantly reduces sediment fall velocities, severely lowering the sediment-trapping efficiency for small or light particles. This reduction in effective fall velocities of sediments suggests a mechanism that fractionates fine particulates (e.g., clays), nutrients (e.g., organic carbon), and pollutants (e.g., microplastics) along transport paths down topographically complex margins.

Role of Pre-Straining on the Mechanical Behaviour of Resistance Spot Welded Ultrahigh Strength Steel

Role of Pre-Straining on the Mechanical Behaviour of Resistance Spot Welded Ultrahigh Strength Steel

Influence of Cold Drawing on Phase Transformation and Tensile Properties of FeCrMn Austenitic Stainless Steel 201

Manganese stabilizes the austenite and reduces the stacking fault energy in face‐centered cubic (FCC) structures, promoting the formation of hexagonal and cubic structures. This study investigates the phase transformation and mechanical behavior of extremely low‐carbon FeCrMn austenitic stainless AISI 201 steel subjected to cold drawing in three stages, ultimately reaching a true strain of 0.93. The objective is to examine the transformation from the parent FCC structure to hexagonal close‐packed and body‐centered cubic structures as a combination of transformation‐induced plasticity and twinning‐induced plasticity phenomena. X‐ray diffraction and electron backscatter diffraction analyses are utilized to investigate phase transformations under significant plastic deformation and the crystallographic orientation relationships between phases. Additionally, tensile and hardness tests are performed to assess the impact of plastic deformation on mechanical properties. Results indicate that a true strain of 50% is optimal for balancing strength and ductility in CrMnFe austenitic stainless steel. After applying a true strain of ε1 = 26.7%, yield strength (YS) increases by 192% and ultimate tensile strength (UTS) by 35%, while elongation reduces by 41%. With a further strain of ε2 = 57.5%, YS increases by 71% and UTS by 44%, but elongation drastically decreases by 94%. Applying the final strain of ε3 = 94.0%, YS and UTS only increase by 3% and 2%, respectively, while elongation further reduced by 40%. These findings suggest that a true strain of 50% shall be considered the maximum reduction for maintaining a balance between strength and ductility in CrMnFe austenitic stainless steel.