Viscoelastic Mechanics Research Articles

Automotive body squeaking noise analysis based on maxwell viscoelastic model

The transition to electric vehicles (EVs) has heightened the significance of secondary noise sources, such as buzz, squeak, and rattle (BSR), which can detract from vehicle quality and customer satisfaction. Among these, body squeaking noise, particularly during the electro-coating (e-coating) process, presents a notable challenge due to its impact on vehicle acoustic comfort. Despite advancements in automotive noise, vibration, and harshness (NVH) control, the specific viscoelastic mechanisms contributing to squeaking noise under varying thermal and mechanical conditions remain inadequately understood. This study addresses these gaps by employing the Maxwell Viscoelastic Model to investigate the time-dependent mechanical behavior of body-in-white (BIW) coatings during the e-coating process. Key finding indicates that the glass transition temperature (Tg) of the coating material plays a critical role in noise occurrence, particularly under high-temperature conditions and road-induced vibrations. This research contributes novel insights to the field by integrating theoretical analysis with empirical data to enhance the understanding of viscoelastic properties in automotive coatings.

Co- and post-seismic deformation of the 2022 Menyuan Mw6.6 earthquake from InSAR and GPS observations

SUMMARY This study combines InSAR (Interferometric Synthetic Aperture Radar) and GPS (Global Positioning System) data to examine the coseismic slip and post-seismic deformation of the 2022 Menyuan Mw 6.6 earthquake, shedding light on the fault structure, slip distribution and rheology of the northeastern Tibetan Plateau. InSAR coseismic deformation revealed fault dip angle of 82° for the Lenglongling fault and 84° for the Tuolaishan fault. The optimal coseismic slip model, derived from InSAR, GPS and near-field pixel-offset data, indicates a maximum slip of 3.3 m, concentrated in the upper 3 km of the fault. We propose a three-step procedure to comprehensively invert the post-seismic deformation, accounting for both afterslip and viscoelastic relaxation, constrained by the InSAR and GPS observations. The optimal afterslip model indicates a cumulative afterslip of 9 cm over two years, primarily concentrated in the deeper sections of the coseismic slip zone. Incorporating viscoelastic relaxation improved the spatial distribution of the afterslip on the Tuolaishan fault. The afterslip released a seismic moment of 1.96 × 10¹⁸ N·m, accounting for approximately 15 per cent of the coseismic moment release. The viscosity of the lower crust in the region was estimated to range from 1.5 to 5 × 1018 Pa·s, with an optimal value of 2 × 10¹⁸ Pa·s. As the distance from the epicentre increased, viscoelastic relaxation became the dominant post-seismic mechanism, contributing up to 80 per cent of the deformation observed at the QHGC and GSMI stations. Additionally, the earthquake increased Coulomb stress on the ‘Tianzhu Seismic Gap’ and nearby faults, raising seismic hazard in the region. These findings highlight the importance of simultaneously considering both afterslip and viscoelastic relaxation mechanisms in post-seismic deformation analysis, and accounting for post-seismic effects when evaluating seismic stress changes.

Experimental and theoretical investigation of Chronic Lymphocytic Leukemia cell's viscoelastic contact mechanics using atomic force microscope

Chronic Lymphocytic Leukemia (CLL) is a type of cancer usually appearing in old age. In this research, a method for detecting CLL cells in young age through the analysis of geometrical and mechanical properties of human Leukocytes has been presented. For this purpose, the CLL cells are cultured and their geometric characteristics, adhesion force, and contact behavior have been examined using an Atomic Force Microscope (AFM) device. Subsequently, the obtained experimental results have been compared with the geometric and mechanical properties of Leukocytes. Furthermore, the manipulation process has been mathematically modeled using different adhesive and non-adhesive contact theories. The results showed that blood cancer cells have up to 8.17% smaller dimensions and up to 23.57% greater elastic modulus compared to leukocytes.

Research on cutting mode and thrust force of major cutting edge for drilling CFRP composite plates based on viscoelastic mechanics and foundation beam theory

Research on cutting mode and thrust force of major cutting edge for drilling CFRP composite plates based on viscoelastic mechanics and foundation beam theory

Direct M2 macrophage co-culture overrides viscoelastic hydrogel mechanics to promote fibroblast activation.

Fibroblast activation drives fibrotic diseases such as pulmonary fibrosis. However, the complex interplay of how tissue mechanics and macrophage signals combine to influence fibroblast activation is not well understood. Here, we use hyaluronic acid hydrogels as a tunable cell culture system to mimic lung tissue stiffness and viscoelasticity. We applied this platform to investigate the influence of macrophage signaling on fibroblast activation. Fibroblasts cultured on stiff (50 kPa) hydrogels mimicking fibrotic tissue exhibit increased activation as measured by spreading as well as type I collagen and cadherin-11 expression compared to fibroblasts cultured on soft (1 kPa) viscoelastic hydrogels mimicking normal tissue. These trends were unchanged in fibroblasts cultured with macrophage-conditioned media. However, fibroblasts directly co-cultured with M2 macrophages show increased activation, even on soft viscoelastic hydrogels that normally suppress activation. Inhibition of interleukin 6 (IL6) signaling does not change activation in fibroblast-only cultures but ameliorates the pro-fibrotic effects of M2 macrophage co-culture. These results underscore the ability of direct M2 macrophage co-culture to override hydrogel viscoelasticity to promote fibroblast activation in an IL6-dependent manner. This work also highlights the utility of using hydrogels to deconstruct complex tissue microenvironments to better understand the interplay between microenvironmental mechanical and cellular cues.

Rupture mechanics of blood clots: Influence of fibrin network structure on the rupture resistance

Embolization is a leading cause of mortality, yet we know little about clot rupture mechanics. Fibrin provides the main structural and mechanical stability to blood clots. Previous studies have shown that altering the concentration of coagulation activators (thrombin or tissue factor (TF)) has a significant impact on fibrin structure and viscoelastic properties, but their effects on rupture properties are mostly unknown. Toughness, which corresponds to the ability to resist rupture, is independent of viscoelastic properties. We used varying TF concentrations to alter the structure and toughness of human plasma clots. We performed single-edge notch rupture tests to examine fibrin toughness under a constant strain rate and we assessed viscoelastic mechanics using rheology. We utilized fluorescent confocal and scanning electron microscopy (SEM) to quantify the fibrin network structure under varying TF concentrations. Our results revealed that increased TF concentration resulted in increased number of fibrin fibers with a reduction in network pore size, thinner and shorter fibrin fibers. Increasing TF concentration yielded a maximum toughness at mid-TF concentration, such that fibrin diameter and number of fibers underlie a complex role in influencing the rupture resistance of blood clots, resulting in a nonmonotonic relationship between TF and toughness. A simple mechanical model, built on our findings from our Fluctuating Spring (FS) computational model, adopted to estimate the fracture toughness (critical energy release rate) as a function of TF predicts trends that are in good agreement with experiments. The differences in mechanical responses point to the importance of studying the structure-function relationships of fibrin networks, which may be predictive of the tendency for embolization. Statement of significanceFibrin, a naturally occurring biomaterial, is the main mechanical and structural scaffold of blood clots that provides the necessary strength and stability to the clot, ensuring effective stemming of bleeding. The rupture of blood clots can result in the blockage of downstream vessels thereby blocking blood flow and oxygen supply. The fibrin network structure has been shown to influence the viscoelastic mechanical properties of clots, but has not been explored for fracture mechanics. Here, we modulate the fibrin network structure by varying the concentration of Tissue Factor (TF). Interestingly, the association between TF concentration and maximum toughness of the clots is non-monotonic. The variations in mechanical responses highlight the importance of studying the structure-function relationships of fibrin networks, as these may predict the tendency for embolization.

A perspective on the time‐dependent structure and properties of amorphous polymer

AbstractA molecular mechanism of viscoelastic deformation is presented. Amorphous polymers are characterized as a heterogeneous network of nanoscale cells. A “cell” is a homogeneous region within the network. Each cell phase fluctuates between the glassy and elastomer states with a period τ. The values of τ vary from cell to cell over several orders of magnitude and are strong functions of temperature. Whether a given cell responds as glassy or elastomeric depends on the ratio between its period of phase fluctuation (τj) and the period of observation (1/f), where f is the test frequency. We express this ratio, the Deborah number, as (τj × f), and present equations for modulus and energy loss as functions of (τj × f). The condition (τj × f) = 1 defines the glass transition of a cell, which arises cell‐by‐cell over a range of temperature, or over a range of time under stress. Viscoelastic deformation occurs if a cell changes phase while under stress. Energy stored during glassy state deformation is lost if the cell fluctuates to the elastomeric state. Stress is out of phase with strain, because strain rate controls the level of stress in glassy cells between phase fluctuations.Highlights A molecular mechanism of viscoelasticity is presented that does not involve viscous flow. Amorphous polymer is a heterogeneous network of nanoscale cells. Cells fluctuate in phase between glassy and elastomeric states due to their size. Time‐dependent properties are caused by time‐dependent structure. Energy is lost when glass phase cells under stress fluctuate to the elastomer phase.

A viscoelastic constitutive framework for aging muscular and elastic arteries

The evolution of arterial biomechanics and microstructure with age and disease plays a critical role in understanding the health and function of the cardiovascular system. Accurately capturing these adaptative processes and their effects on the mechanical environment is critical for predicting arterial responses. This challenge is exacerbated by the significant differences between elastic and muscular arteries, which have different structural organizations and functional demands. In this study, we aim to shed light to these adaptive processes by comparing the viscoelastic mechanics of autologous thoracic aortas (TA) and femoropopliteal arteries (FPA) in different age groups. We have extended our fractional viscoelastic framework, originally developed for FPA, to both types of arteries. To evaluate this framework, we analyzed experimental mechanical data from TA and FPA specimens from 21 individuals aged 13 to 73 years. Each specimen was subjected to a multi-ratio biaxial mechanical extension and relaxation test complemented by bidirectional histology to quantify the structural density and microstructural orientations. Our new constitutive model accurately captured the mechanical responses and microstructural differences of the tissues and closely matched the experimentally measured densities. It was found that the viscoelastic properties of collagen and smooth muscle cells (SMCs) in both the FPA and TA remained consistent with age, but the viscoelasticity of the SMCs in the FPA was twice that of the TA. Additionally, changes in collagen nonlinearity with age were similar in both TA and FPA. This model provides valuable insights into arterial mechanophysiology and the effects of pathological conditions on vascular biomechanics. Statement of significanceDeveloping durable treatments for arterial diseases necessitates a deeper understanding of how mechanical properties evolve with age in response to mechanical environments. In this work, we developed a generalized viscoelastic constitutive model for both elastic and muscular arteries and analyzed both the thoracic aorta (TA) and the femoropopliteal artery (FPA) from 21 donors aged 13 to 73. The derived parameters correlate well with histology, allowing further examination of how viscoelasticity evolves with age. Correlation between the TA and FPA of the same donors suggest that the viscoelasticity of the FPA may be influenced by the TA, necessitating more detailed analysis. In summary, our new model proves to be a valuable tool for studying arterial mechanophysiology and exploring pathological impacts.

Universal phase-field mixture representation of thermodynamics and shock-wave mechanics in porous soft biologic continua.

A continuum mixture theory is formulated for large deformations, thermal effects, phase interactions, and degradation of soft biologic tissues suitable at high pressures and low to very high strain rates. Tissues consist of one or more solid and fluid phases and can demonstrate nonlinear anisotropic elastic, viscoelastic, thermoelastic, and poroelastic physics. Under extreme deformations or shock loading, tissues may fracture, tear, or rupture. Existing models do not account for all physics simultaneously, and most poromechanics and soft-tissue models assume incompressibility of some or all constituents, generally inappropriate for modeling shock waves or extreme compressions. Motivated by these prior limitations, a thermodynamically consistent formulation that combines a continuum theory of mixtures, compressible nonlinear anisotropic thermoelasticity, viscoelasticity, and phase-field mechanics of fracture is constructed to resolve the pertinent physics. A metric tensor of generalized Finsler space supplies geometric insight on effects of rearrangements of microstructure, for example degradation, growth, and remodeling. Shocks are modeled as singular surfaces. Hugoniot states and shock decay are analyzed: Solutions account for concurrent viscoelasticity, fracture, and interphase momentum and energy exchange not all contained in previous analyses. Suitability of the framework for representing blood, skeletal muscle, and liver is demonstrated by agreement with experimental data and observations across a range of loading rates and pressures. Insight into previously unresolved physics is obtained, for example importance of rate sensitivity of damage and quantification of effects of dissipation from viscoelasticity and phase interactions on shock decay.

New theory to explain the effect of lactose fines on the performance of adhesive mixtures for inhalation

A new theory for the dispersibility enhancing effect of excipient fines for adhesive mixtures for inhalation is presented in this paper, while at the same time the shortcomings of current hypotheses are discussed. The proposed mechanism, denoted the ‘viscoelastic damping effect’, states that the presence of fines particles acts to dampen the collisions between carrier particles during mixing. As a consequence, fewer fine particles are ‘irreversibly’ pressed into the carriers, which in turn entails a higher fine particle fraction. The mechanism was demonstrated experimentally at different levels of added lactose fines by studying the influence of processing on fine particle fraction. This approach furthermore enabled quantification of the effect. All fine particles present in the blend (APIs and excipient fines) act together to exert the damping effect. The proposed mechanism is able to explain the main body of published data, including the effect of added excipient fines, the effect of an increased drug load, and the effect of removal of carrier fines. The viscoelastic damping mechanism is general in nature and conveys a broader and more general understanding of the behavior of adhesive mixtures for inhalation.

Viscoelastic and Birefringence Relaxation of Individualized Cellulose Nanofibers in the Dilute and Semidilute Regions.

Viscoelastic relaxation mechanisms of individualized cellulose nanofibers (iCNFs) dispersed in glycerol in the dilute and semidilute regions were investigated by linear viscoelastic and dynamic birefringence measurements. The birefringence relaxation of the iCNFs was described by the orientational and curvature modes of an existing viscoelastic theory for ideal semiflexible polymers (Shankar-Pasquali-Morse theory). However, the Shankar-Pasquali-Morse theory could not fully describe the iCNF viscoelastic relaxation at high frequencies. Considering the results for birefringence relaxation, the experimental tension mode of the iCNFs was evaluated to be higher than the theoretical value. These results show that the viscoelastic relaxations of the iCNFs are different from those of ideal semiflexible polymers, in contrast to cellulose nanocrystals (CNCs). As the iCNF concentration increased, the orientational mode dramatically slowed, which was more drastic than other semiflexible polymers, including CNCs. This anomalous behavior is likely due to the nonideal nature of iCNFs.

Contribution of ankle motion pattern during landing to reduce the knee-related injury risk

BackgroundSingle-leg landing (SL) is an essential technique in sports such as basketball, soccer, and volleyball, which is often associated with a high risk of knee-related injury. The ankle motion pattern plays a crucial role in absorbing the load shocks during SL, but the effect on the knee joint is not yet clear. This work aims to explore the effects of different ankle plantarflexion angles during SL on the risk of knee-related injury. MethodsThirty healthy male subjects were recruited to perform SL biomechanics tests, and one standard subject was selected to develop the finite element model of foot-ankle-knee integration. The joint impact force was used to evaluate the impact loads on the knee at various landing angles. The internal load forces (musculoskeletal modeling) and stress (finite element analysis) around the knee joint were simulated and calculated to evaluate the risk of knee-related injury during SL. To more realistically revert and simulate the anterior cruciate ligament (ACL) injury mechanics, we developed a knee musculoskeletal model that reverts the ACL ligament to a nonlinear short-term viscoelastic mechanical mechanism (strain rate-dependent) generated by the dense connective tissue as a function of strain. ResultsAs the ankle plantarflexion angle increased during landing, both the peak knee vertical impact force (p = 0.001) and ACL force (p = 0.001) decreased significantly. The maximum von Mises stress of ACL, meniscus, and femoral cartilage decreased as the ankle plantarflexion angle increased. The overall range of variation in ACL stress was small and was mainly distributed in the femoral and tibial attachment regions, as well as in the mid-lateral region. ConclusionThe current findings revealed that the use of larger ankle plantarflexion angles during landing may be an effective solution to reduce knee impact load and the risk of rupture of the medial femoral attachment area in the ACL. The findings of this study have the potential to offer novel perspectives in the optimized application of landing strategies, thus giving crucial theoretical backing for decreasing the risk of knee-related injury.

Investigating viscoelastic properties and structural stability mechanisms of oil bodies emulsion gels: Role of non-intrinsic protein

This research aims to investigate the mechanism of the effect of intrinsic and non-intrinsic protein content on the stability of oil bodies (OBs) emulsion gels. We employed small amplitude oscillation shear (SAOS) and large amplitude oscillation shear (LAOS) to measure the linear and nonlinear rheological properties of the OBs emulsion gels. The SAOS test indicated that an increase in non-intrinsic protein content weakened the interaction between OBs, decreasing their storage modulus (G'). The LAOS test demonstrated that the increase in non-intrinsic protein content affected the structural recombination and destruction behavior of OBs emulsion gels under large strains. Overall, the content of non-intrinsic protein during the extraction process is a crucial factor affecting the stability of OBs emulsion gels. These findings provide insights into the potential strategies for improving oil extraction efficiency and offer a foundation for further investigation into the functional properties of OBs.

Experimental study on creep-fatigue damage of hot central plant recycling asphalt mixture containing high RAP

The objective of this study is to delve into the nonlinear damage evolution mechanism of hot central plant recycling asphalt mixture under the influence of creep-fatigue interaction. A predictive model for lifespan, considering the interaction of temperature and load, was developed. Dynamic creep tests were conducted at different temperatures to assess the creep effect of the asphalt mixture under actual road temperature conditions. The investigation began by acknowledging the material's viscoelastic properties, thereby deriving the loss compliance value - a key indicator of temperature effects - using an equivalent conversion factor and a viscoelastic mechanics model. This allowed for the incorporation of creep behavior into the load system. Furthermore, to analyze the nonlinear damage mechanism and fatigue prediction mechanism, direct tensile fatigue tests were performed at different temperatures and different stress levels. The fatigue damage evolution law of hot central plant recycling asphalt mixture containing high RAP considering the creep effect was revealed, and the fatigue life evaluation method under the combined action of temperature and stress level was proposed. The results show that the fitting degree of the time-temperature conversion equation and the viscoelastic mechanics model to the test data is more than 0.9, and the derived loss compliance value better captures the creep effect. Based on the nonlinear creep-fatigue damage model, the damage law of high-RAP hot central plant recycling asphalt mixture was identified. The optimized fatigue life prediction model fully considers the combined effect of temperature and stress level and analyzes the influence parameters of the real state of pavement fatigue. The prediction accuracy is within the requirements of engineering applications. The model's predictive accuracy meets the criteria for engineering applications, enhancing the multifaceted damage coupling analysis approach for hot central plant recycling asphalt mixture and predict the service life of recycled pavements under complex conditions, establishing a groundwork for the prediction and assessment of long-lasting recycled pavements.

Automated Shape Correction for Wood Composites in Continuous Pressing

The effective and comprehensive utilization of forest resources has become the theme of the global “dual-carbon strategy”. Forestry restructured wood is a kind of wood-based panel made of wood-based fiber composite material by high-temperature and high-pressure restructuring–molding, and has become an important material in the field of construction, furniture manufacturing, as well as derivative processing for its excellent physical and mechanical properties, decorative properties, and processing performance. Taking Medium Density Fiberboard (MDF) as the recombinant material as the research object, an event-triggered synergetic control mechanism based on interventional three-way decision making is proposed for the viscoelastic multi-field coupling-distributed agile control of the “fixed thickness section” in the MDF continuous flat-pressing process, where some typical quality control problems of complex plate shape deviations including thickness, slope, depression, and bump tend to occur. Firstly, the idea of constructing the industrial event information of continuous hot pressing based on information granulation is proposed, and the information granulation model of the viscoelastic plate shape process mechanism is established by combining the multi-field coupling effect. Secondly, an FMEA-based cyber granular method for diagnosing and controlling the plate thickness diagnosis and control failure information expression of continuous flat pressing is proposed for the problems of plate thickness control failure and plate thickness deviation defect elimination that are prone to occur in the continuous flat-pressing process. The precise control of the plate thickness in the production process is realized based on event-triggered control to achieve the intelligent identification and processing of the various types of faults. The application test is conducted in the international mainstream production line of a certain type of continuous hot-pressing equipment for the production of 18 mm plate thickness; the synergistic effect is basically synchronized after 3 s, the control accuracy reaches 30%, and the average value of the internal bond strength is 1.40, which ensures the integrity of the slab. Practical tests show that the method in the actual production is feasible and effective, with detection and control accuracy of up to ±0.05 mm, indicating that in the production of E0- and E1-level products, the rate of superior products can reach more than 95%.

Unveiling the temperature-dependent mechanisms of viscoelasticity of sand-enhanced epoxy

The viscoelastic behavior of epoxy is critical for its engineering performance and applications. This work focused on the improvement of its viscoelastic performance by using natural sand particles as fillers. Experiments were carried out to investigate the static and dynamic viscoelastic properties of epoxy with various sand particle contents. Static mechanical tests demonstrated an increase in the elastic modulus, albeit at the cost of reduced strength at a higher sand content due to stress concentrations. Dynamic tests indicated substantially improved storage modulus and damping of epoxy after being filled with sand particles. Moreover, the glass transition temperature of epoxy showed a substantial rise upon the addition of sand particles, signifying an augmentation in its heat resistance. Static viscoelastic characterization revealed an elevation in both room- and high-temperature relaxation moduli upon incorporating sand. By applying time–temperature superposition principles, long-term relaxation curves were obtained, which could provide a reference for engineering design. These viscoelastic investigations offer insights into the underpinning mechanisms governing the performance of sand-reinforced epoxy. This enables the rational design of sand-particle-reinforced epoxy for customized durability, heat resistance and vibration damping.

Rapidly damping hydrogels engineered through molecular friction

Hydrogels capable of swift mechanical energy dissipation hold promise for a range of applications including impact protection, shock absorption, and enhanced damage resistance. Traditional energy absorption in such materials typically relies on viscoelastic mechanisms, involving sacrificial bond breakage, yet often suffers from prolonged recovery times. Here, we introduce a hydrogel designed for friction-based damping. This hydrogel features an internal structure that facilitates the motion of a chain walker within its network, effectively dissipating mechanical stress. The hydrogel network architecture allows for rapid restoration of its damping capacity, often within seconds, ensuring swift material recovery post-deformation. We further demonstrate that this hydrogel can significantly shield encapsulated cells from mechanical trauma under repetitive compression, owing to its proficient energy damping and rapid rebound characteristics. Therefore, this hydrogel has potential for dynamic load applications like artificial muscles and synthetic cartilage, expanding the use of hydrogel dampers in biomechanics and related areas.

A novel post‐forming method for fully cured thermosetting composite parts: Prediction and investigation

AbstractThe objective of this work is to devise a post‐forming technique capable of accurately and significantly altering the shape of fully cured thermosetting composite parts. To accomplish this goal, the viscoelastic behavior and resulting deformation of fully cured parts at elevated temperatures were predicted and examined using viscoelastic mechanics, finite element analysis (FEA), surrogate modeling, and the particle swarm optimization (PSO) method. Firstly, the mechanism of fully cured parts' shape adjustment based on viscoelastic mechanics was introduced, and a method was established for the inverse identification of the stress relaxation ratio in the different directions of material. Secondly, an FEA model for predicting post‐forming was developed based on the standard linear‐solid viscoelastic model. A dataset was then compiled using parameterized FEA to train a rapid prediction model for post‐forming. The influence of various forming and structural parameters on the post‐forming process was examined. The results indicate that layup has the most significant impact, followed by displacement and temperature. The radial basis function was selected to construct the precise surrogate model after comparing it with the Kriging model and the Response Surface Methodology (RSM) model. Ultimately, to achieve the desired shape after post‐forming, the PSO method can be employed to determine the ideal combination of forming parameters.Highlights The post‐forming method could adjust the shape of fully cured composites. The mechanism of post‐forming is based on viscoelastic behavior. An accurate FEA based on the standard linear‐solid model was established. The radial basis function was developed for quick and precise prediction. The particle swarm optimization could obtain the ideal forming parameters.

Influence of restricted visual input on lower limb joint works of female children during sit-to-stand

BackgroundThe ankle-knee-hip joint systems have structures that can produce mechanical work through elastic, viscoelastic mechanisms or muscle activity. This study aimed to compute sit-to-stand (STS) joint works in lower limbs between blind and sighted children to find the relationship between visual memory and STS joint work variables. MethodsThis study included fifteen female children with congenitally blind (CB) and 30 healthy girls without visual impairments. The children with no visual impairments were randomly divided into two condition groups with 15 each, the eyes open (EO) and the eyes closed (EC). Inverse dynamics calculated joint works by integrating multiple the moment and angular velocity (F1) and force and velocity (F2). They were normalized to body mass and body height. ResultsGenerally, the sensitivity of F1 (on both sides in the sagittal and frontal planes) was more than F2 (on the non-dominant side in the mediolateral and vertical axes). In the ML axis, the EC group had insufficient maximal non-dominant hip work relative to the EO group (p = 0.002). In addition, the CB group suffered from low hip efficiency (p = 0.003) and high knee (p < 0.001) mechanical work. ConclusionsNumerous differences between CB and EC groups (on knee and hip works) showed that the time of visual input deprivation could change the type of human body's strategies to reach the consolidation process and keep adequate balance during STS. Therefore, rehabilitation programs should be aimed at addressing the impairments in the management of restricted visual input during STS performance.

Multi‐physics field coupling modeling and simulation to study the stress evolution during HTCLS curing process

AbstractHybrid titanium carbon laminates (HTCLs) are a new type of fiber metal laminates, that are attracting extensive attention due to their comprehensive mechanical and physical properties. The curing stress is an important factor affecting the manufacturing performance of HTCLs. Based on viscoelastic mechanics and temperature variation characteristics of materials in this work, the multi‐physics field coupling modeling and simulation are conducted, and the stress evolution mechanism during HTCLs curing process is investigated. Furthermore, the interlayer interfacial damage of HTCLs induced by the curing stress is analyzed combined with the microscope images. Results show that the restriction of metal layers and the stacking sequence of carbon fiber prepregs are the primary reasons for generating significant stress during HTCLs curing. The secondary insulation stage of HTCLs curing process has a positive effect on suppressing the curing stress, by which the interfacial stress between the different metal layers and prepregs layers can decrease by 10.53%, 4.06%, 10.24%, and 1.11%. From the beginning of cooling to the end of curing, the residual stress in HTCLs increases rapidly, and the maximum can increase by 197%. Stress concentration is easily generated on the edges of HTCLs, and the interfaces near the bottom of HTCLs are more prone to forming cracks and delamination.Highlights A multi‐physics field coupling model for HTCLs curing process is established. The viscoelastic mechanics and the temperature variation characteristics of materials are considered in this model. The stress evolution mechanism during HTCLs curing is studied. The interface damage of HTCLs induced by the curing stress is analyzed combined with experiments.