Impact Response Research Articles

Dynamic analysis of a box-structured satellite deployment mechanism with self-actuated torsion joints

Abstract. This paper designed a kind of satellite deployment mechanism with a boxed structure and passive torsion joints. This deployment mechanism has significant strengths, including a high base frequency and stiffness, a high ratio of deployed and folded space occupation ratios, and self-actuated joints without needing any external power to drive. In order to analyze the dynamic characteristics of this mechanism, a simplified governing equation is proposed and dynamic behavior is studied systematically, including impact response, harmonic response, and modal analysis. Through systematic research, several conclusions are drawn. Firstly, when the deployment mechanism reached the ending stage of unfolding driven by passive torsional joints, the load base installed on top of the deployment mechanism generated a first-order sharp reaction force and multiple low-order shocks followed, and the system entered a stable state after a certain time of vibration. Secondly, the system can generate a high vibration magnitude at low-frequency excitation when the mechanism is in a fully deployed state and at high-frequency excitation when the mechanism is in a folded state. Thirdly, the first sixth-order natural frequency and vibration shape with different wall thicknesses are obtained by modal analysis. The result shows that only with a 2.5 mm wall thickness can the connecting rod satisfy the design requirement. Through dynamic behavior research, the structure characteristics are obtained which can be used for structure optimization and to provide an effective solution for the design of a box-structured satellite-unfolding mechanism with self-actuated torsion joints.

The Environmental Impact of E-Waste Microplastics: A Systematic Review and Analysis Based on the Driver–Pressure–State–Impact–Response (DPSIR) Framework

Microplastics resulting from the fragmentation of plastics in electronic waste (e-waste) are an emerging but understudied environmental concern. This systematic review employs a Driver–Pressure–State–Impact–Response (DPSIR) framework to investigate the sources, prevalence, and environmental effects of e-waste microplastics, identifying knowledge gaps. The available literature on e-waste microplastics was retrieved from Scopus and Web of Science (n = 24), and trends in electrical and electronic equipment were retrieved from European Union databases. The growing incorporation of electronics into daily life results in a global annual growth rate of 3–4% for e-waste, of which only 17.4% is collected for recycling. E-waste microplastics are frequently found in soils near disposal or disassembly facilities, potentially leaching hazardous metals (e.g., Pb) or organic compounds (e.g., flame retardants). These microplastics contaminate the food chain and can have adverse effects on the soil and gut microbiome, organisms, and human health, either independently or associated with other chemicals. Responses include the implementation of regulations, improvement of waste management systems, and mitigation measures. Despite these concerns, the literature on the topic remains limited, emphasizing the need for additional research on the identification of e-waste microplastics and their toxicity.

Investigating damage resistance in aerospace radome applications: Experimental analysis of hybrid sandwich composites

This research introduces an innovative hybrid sandwich composite structure tailored for specific applications, featuring a foam core and dissimilar face sheets made of Kevlar and S-Glass materials to address in-phase electromagnetic properties, UV protection, and impact response. Building on our prior work on design optimization for electromagnetic performance and aero/inertial loading, this paper investigates the low-velocity impacts (LVIs) response of the composite structure through drop-weight testing at various energy levels. Utilizing computed tomography (CT) scanning for damage analysis, distinct failure modes were observed for different face sheet combinations, with notable variations (energy absorption characteristics) in damage depth and width between the S-Glass and Kevlar face sheets. This study, unprecedented in existing literature, proposes hybrid sandwich structures with superior specific impact strength compared to various composite sandwich structures documented in the published literature expanding its utility beyond radomes.

Decoupling particle-impact dissipation mechanisms in 3D architected materials

Ultralight architected materials enabled by advanced manufacturing processes have achieved density-normalized strength and stiffness properties that are inaccessible to bulk materials. However, the majority of this work has focused on static loading and elastic-wave propagation. Fundamental understanding of the mechanical behavior of architected materials under large-deformation dynamic conditions remains limited, due to the complexity of mechanical responses and shortcomings of characterization methods. Here, we present a microscale suspended-plate impact testing framework for three-dimensional micro-architected materials, where supersonic microparticles to velocities of up to 850 m/s are accelerated against a substrate-decoupled architected material to quantify its energy dissipation characteristics. Using ultra-high-speed imaging, we perform in situ quantification of the impact energetics on two types of architected materials as well as their constituent nonarchitected monolithic polymer, indicating a 47% or greater increase in mass-normalized energy dissipation under a given impact condition through use of architecture. Post-mortem characterization, supported by a series of quasi-static experiments and high-fidelity simulations, shed light on two coupled mechanisms of energy dissipation: material compaction and particle-induced fracture. Together, experiments and simulations indicate that architecture-specific resistance to compaction and fracture can explain a difference in dynamic impact response across architectures. We complement our experimental and numerical efforts with dimensional analysis which provides a predictive framework for kinetic-energy absorption as a function of material parameters and impact conditions. We envision that enhanced understanding of energy dissipation mechanisms in architected materials will serve to define design considerations toward the creation of lightweight impact-mitigating materials for protective applications.

The relationship between money supply and inflation: analysis with PANELVAR approach

The relationship between money supply and inflation: analysis with PANELVAR approach

Analysis of low-velocity impact on FG-CNT reinforced cantilever sandwich beams: An FOSNDT approach

This study analyzes the low-velocity impact response of cantilever sandwich beams with foam cores and carbon nanotube (CNT) reinforced facesheets. Using the fifth-order shear and normal deformation theory, we explore three CNT distribution types through the thickness of the facesheets: uniformly distributed UD, functionally graded-V FG-V, and functionally graded-Λ FG-Λ. The contact force during impact is calculated according to Hertz contact law. Our findings indicate that the FG-V distribution offers the highest contact stiffness, resulting in reduced deflection compared to UD and FG-Λ distributions. Additionally, an increase in the core-to-face thickness ratio leads to decreased deflection and increased contact force, attributed to enhanced beam stiffness. The volumetric fraction of CNTs also plays a critical role, increased CNT content raises beam stiffness, decreasing deflection and enhancing contact force. Furthermore, the impactor’s initial velocity directly influences the deflection and contact force, with higher velocities leading to greater deflections due to increased kinetic energy. This comprehensive analysis underscores the significant effects of CNT distribution, volumetric fraction, and geometrical parameters on the dynamic response of sandwich beams under impact conditions.

Review on impact, crushing response and applications of re-entrant core sandwich structures

PurposeAuxetic sandwich structures are gaining attention because of the negative Poisson’s ratio effect offered by these structures. Re-entrant core was one configuration of the auxetic structures. There is a growing concern about the design and behavior of re-entrant cores in aerospace, marine and protection applications. Several researchers proposed various designs of re-entrant core sandwiches with various materials. The purpose of this study is to review the most recent advances in re-entrant core sandwich structures. This review serves as a guide for researchers conducting further research in this wide field of study.Design/methodology/approachThe re-entrant core sandwich structures were reviewed in terms of their design improvements, impact and quasi-static crushing responses. Several design improvements were reviewed including 2D cell, 3D cell, gradient, hierarchical and hybrid configurations. Some common applications of the re-entrant core sandwiches were given at the end of this paper with suggestions for future developments in this field.FindingsGenerally, the re-entrant configuration showed improved energy absorption and impact response among auxetic structures. The main manufacturing method for re-entrant core manufacturing was additive manufacturing. The negative Poisson’s ratio effect of the re-entrant core provided a wide area of research.Originality/valueGenerally, re-entrant cores were mentioned in the review articles as part of other auxetic structures. However, in this review, the focus was solely made on the re-entrant core sandwiches with their mechanics.

Peran Konsep Diri dalam Mengurangi Konsekuensi Psikologis dari Cyberbullying

This research investigates the psychological impact of cyberbullying on individuals' self-concept and analyzes the strategies and coping mechanisms used to reduce the negative consequences that arise. Using a qualitative approach, in-depth interviews were conducted with a number of participants who had experienced cyberbullying. Findings suggest variation in how individuals respond to these experiences, with some experiencing reduced self-esteem, while others develop adaptive strategies to cope with the psychological impact. Social support, developing mental resilience, self-reflection, managing social media, and seeking professional help were identified as key strategies. The results of this study provide in-depth insight into the complexity of the impact and individual responses to cyberbullying, and provide a foundation for the development of more effective interventions.

Impact Response of Polyurea Elastomeric Foams

Impact Response of Polyurea Elastomeric Foams

Impact response of stainless steel tube locally-strengthened by concrete-filled steel tube

This paper proposes a novel stainless-steel tube locally strengthened by a concrete-filled steel tube to resist impact loads. A drop hammer impact test system was used to determine the failure modes, impact forces, and displacement responses of the strengthened tubes under an impact load. The effects of the strengthening length and thickness of the concrete and outer steel tubes on the impact responses of the strengthened tubes were investigated. The impact resistance was found to improve with an increase in the thickness of the concrete and outer steel thickness. The test results also indicated that the strengthened tubes exhibited a flexural failure mode with a combination of local and global deformations. An analytical model for predicting the dynamic responses of the locally strengthened tubes was established based on an equivalent two-degree-of-freedom (TDOF) model. The analytically predicted results were compared with the experimental results, and the good consistency between these two results demonstrated the accuracy of the established analytical model.

Investigation of the influence of Halloysite Nanotubes (HNTs) on the low-velocity impact behavior of carbon fiber-reinforced epoxy composites

This study explores the impact of incorporating Halloysite Nanotubes (HNTs) nanoparticles on the low-velocity impact (LVI) behavior of carbon fiber (CF) laminate epoxy nanocomposites. The objective of this investigation was to observe the effects of different nanotube loadings (0.5[Formula: see text]wt.% and 0.7[Formula: see text]wt.%) on CF composites and assess their impact resistance. To achieve this, the CF was subjected to Electrophoretic Deposition (EPD) process to introduce the HNTs. Vacuum-assisted Resin Transfer Molding (VaRTM) was employed to fabricate the CF-reinforced epoxy-based laminated nanocomposites with incorporated HNTs. LVI tests were conducted following the ASTM-D-7136 standard, utilizing impact energies of 10[Formula: see text]J and 15[Formula: see text]J. Subsequently, the damaged areas within the composites were examined using optical microscopy (OM) and scanning electron microscope (SEM). The findings of this investigation revealed a significant enhancement in impact damage resistance with the addition of HNTs. The highest damage resistance and minimal energy absorption were observed at a loading of 0.7[Formula: see text]wt.% HNTs. The results reveal that incorporating 0.7[Formula: see text]wt.% HNTs substantially reduces delamination damage, influenced by absorbed impact energy. As well it composite underscores enhanced interlaminar bonding through 0.5[Formula: see text]wt.% and 0.7[Formula: see text]wt.% HNTs modification. Hence, we confidently assert that the addition of HNTs nanoparticles to CF/epoxy composites has considerably influenced the impact response of the nanocomposites.

Low-velocity impact response of a novel bionic turtle shell back armor sandwich structure

Turtle shell dorsal armor comprises a typical lightweight laminated composite structural material, which is constructed by cuticle and bone layer, with high specific strength and high fracture toughness. The red-eared slider turtle, a widely studied species of turtle, has a rich hierarchical structure. In this paper, according to the structure of red-eared slider turtle shell dorsal armor and the characteristics of each layer as well as by taking into full consideration of the fine structure of cuticle and ventral cortex of the shell dorsal armor, two bionic foam silicone rubber sandwich structures of different levels were prepared. Low-velocity impact test and finite element simulation analysis were carried out to study the mechanical response, specific absorbed energy, and damage mode of the two bionic sandwich structures under different impact energies, hammerhead shapes, and hammerhead radii. By comparing the mechanical response and specific energy absorption with the existing ordinary sandwich structure, we find that the two sandwich structures modeled in this paper exhibit better impact resistance than the ordinary sandwich structure. The shape and radius of the hammer head have a significant effect on the energy absorption characteristics of the sandwich structure, and the damage mode under the hemispherical hammer head is mainly dominated by tensile tearing damage, while the damage mode of extrusion fracture is more obvious under the impact of the conical hammer head. With the increase of the radius of the hammer head, the absorbed energy and specific energy absorption of the sandwich structure increases.

Effect of fibre hybridization and stacking sequence on the low velocity impact response of flax/basalt/aluminum composite-metal joints

A lot of composite materials with better impact resistance and better strength and stiffness can be manufactured these days. Many researchers have been using different materials to form new composites to understand their impact performance. This paper discusses such an attempt to make new composites by utilizing the concept of hybridization and then proposes which among them has better strength and performance under low-velocity impact (LVI) loading. In this work, circular patches of composites made up of a combination of basalt and flax fibers were used while being bonded with aluminum plate Al 2024-T3 of 3 mm thickness. The three different configurations which include asymmetric, symmetric, and sandwich were prepared using vacuum assisted bagging process and their impact performances were investigated using the Drop Weight Impact test. The results obtained were analyzed and they concluded that the asymmetric configuration of basalt/flax composite has better impact resistance, and strength and is better to use in structural components of automobiles, and the defense industry as compared to the other two.

Comparison of two progressive damage models for predicting low-velocity impact behavior of woven composites

This research focuses on comparing the two progressive damage models available in the explicit nonlinear finite element software LS-Dyna. To explore the prediction capabilities in terms of mechanical response and dominating failure modes in S2 glass woven composites, low velocity impact response at four different energies ranging from 27.9 J to 109.7 J were considered in this study. A macro-homogeneous solid element formulated finite element model was simulated to understand the response and failure mechanics in the laminate under low-velocity impact. The material modeling was carried out utilizing the MAT 55 and MAT 162 material models. An effort has been made for robust calibration of the various physical and non-physical parameters in both material cards for accurate predictions. The prediction capabilities of the models were then examined by comparing them against the experimental results, which fall within the deviation of ∼11%. The results show that MAT 162 yields a better resemblance with the damage morphology patterns and the delamination for the accounted impact zone, due to inclusion of strain-rate effect. Overall, this paper provides insight into the limitations and advantages of both material models, which establishes the route for the selection of the appropriate material model for simulating impact behavior in woven composites.

Driving Force–Pressure–State–Impact–Response-Based Evaluation of Rural Human Settlements’ Resilience and Their Influencing Factors: Evidence from Guangdong, China

During urbanization, rural human settlements experience dual pressures from both ecology and culture. Strengthening resilience can enhance the system’s ability to withstand external pressures and restore equilibrium, providing a new research perspective and practical approach for the sustainable development of rural areas. Yet, there are limited reports in the literature on evaluating and improving rural human settlements resilience. To fill this gap, the paper establishes an evaluation system utilizing the DPSIR framework and entropy method. It employs 115 counties and districts in Guangdong Province as samples to evaluate rural human settlements’ resilience in 2020. The Geographically Weighted Regression (GWR) model is used to analyze spatial differences and the influencing mechanisms of various factors on resilience. The results suggest that the overall rural human settlements’ resilience in Guangdong Province is relatively low, showing a concentrated spatial distribution and also variations in the levels and spatial distributions of resilience across different dimensions. Moreover, various dimensions of resilience significantly impact rural human settlements. The driving force resilience coefficients are all significantly positive, with higher values in Western Guangdong and Eastern Guangdong. The pressure resilience coefficients are all significantly negative, decreasing from east to west. The state resilience coefficients show an overall positive correlation, with lower values in the central and northern parts and higher values in the eastern and western parts. The impact resilience and response resilience coefficients are generally positive, with higher values in the Pearl River Delta. This paper extends the theoretical framework for evaluating and analyzing rural human settlements’ resilience, offering empirical evidence to optimize their resilience in a geographical context.

Damage mechanisms in composite laminated shells subjected to multiple impacts at different points

AbstractThis study investigates the effect of damage interference resulting from impact loads on the mechanical response and impact fatigue life of E‐glass/epoxy composite laminate shells. The analysis involves single impacts at different points to evaluate the impact strength's dependency on boundary conditions. Notably, there is a gradual reduction in both maximum impact force and absorbed energy beyond 10 mm from the centre, towards unconstrained edges, accompanied by an increase in displacement. Specifically, at a distance of 30 mm, the maximum force and absorbed energy register a decrease of 9.4% and 7.9%, respectively, while the displacement rises by 14.5%. The findings reveal that the damage severity decreases as the impact point is closer to the unconstrained edge of the specimen, which can be attributed to a stiffness reduction, which can reach up to 22%. Symmetrically induced pre‐damages exhibit no discernible effect on the subsequent impact response. It is observed that beyond 10 mm from the shell's centre, the number of impacts required to reach puncture increases by 10.5% and 21.1% for distances of 20 and 30 mm, respectively. Furthermore, it is also found that alternating impacts between symmetrical points show no inclination towards a preferential point for puncture.Highlights The single impact strength's dependents on the boundary conditions. Reduction in both maximum impact force and absorbed energy near the unconstrained edges. Damage severity decreases as the impact point is closer to the unconstrained edges. Symmetrically induced pre‐damages have no discernible effect on the subsequent impact response. Alternating impacts between symmetrical points show no inclination towards a preferential point for puncture.

Impact response of composite energy absorbers based on foam-filled metallic and polymeric auxetic frames

In this paper, an innovative concept is proposed, based on the hexachiral auxetic frames filled with foams with enhanced energy absorption capabilities. Numerical assessments of the composite foam-filled auxetic absorbers, of pure foam blocks and unfilled auxetic frames for metallic and polymeric material combinations were accomplished considering a case of localized impact. The energy absorbed by the composite absorbers are found superior to the sum of the energies absorbed by constituent elements tested separately with clear advantages also at the level of the specific energy absorbed per unit mass. The interactions between the two constituents are analyzed and discussed. An experiment considering a 3D-printed polymeric hexachiral frame filled with open-cell soft polyurethane foam under localized impact is conducted to validate the numerical approach. Eventually, a parametric sensitivity study is conducted numerically to illustrate the effects of geometrical parameters on the energy absorption capacity. Overall, the results confirm the potential and the great design flexibility of the concept, provides the guidelines to design advanced energy absorbing system, underlies the importance of the combination between the frame and foam properties and the effect of the main geometrical parameters on the performance.

Brain Material Properties and Integration of Arachnoid Complex for Biofidelic Impact Response for Human Head Finite Element Model.

Finite element head models offer great potential to study brain-related injuries; however, at present may be limited by geometric and material property simplifications required for continuum-level human body models. Specifically, the mechanical properties of the brain tissues are often represented with simplified linear viscoelastic models, or the material properties have been optimized to specific impact cases. In addition, anatomical structures such as the arachnoid complex have been omitted or implemented in a simple lumped manner. Recent material test data for four brain regions at three strain rates in three modes of loading (tension, compression, and shear) was used to fit material parameters for a hyper-viscoelastic constitutive model. The material model was implemented in a contemporary detailed head finite element model. A detailed representation of the arachnoid trabeculae was implemented with mechanical properties based on experimental data. The enhanced head model was assessed by re-creating 11 ex vivo head impact scenarios and comparing the simulation results with experimental data. The hyper-viscoelastic model faithfully captured mechanical properties of the brain tissue in three modes of loading and multiple strain rates. The enhanced head model showed a high level of biofidelity in all re-created impacts in part due to the improved brain-skull interface associated with implementation of the arachnoid trabeculae. The enhanced head model provides an improved predictive capability with material properties based on tissue level data and is positioned to investigate head injury and tissue damage in the future.

Study on the low‐velocity impact response of the repaired carbon fiber‐reinforced plastic laminates: Bonded versus scarf repair

AbstractExperimental and simulation studies of the response of bonded‐repaired and scarf‐repaired carbon fiber‐reinforced polymer laminates under the low‐velocity impact (LVI) were carried out. The center‐ and eccentric‐repaired laminates were prepared for experiments. The experimental results verify the validity of the finite element model in terms of the force response and different modes of damage. The effect of impact energy and the variation of repair position on the impact response of the laminate was investigated based on the benchmark model. The bonded repaired laminates have higher peak impact forces and lower energy absorption than the scarf‐repaired laminates; the damage of the bonded repaired laminate is mainly intralaminar damage and delamination damage of the patch; the adhesive of the scarf repair is prone to failure, leading to poor impact resistance. The relative positions of the impact point and the patch determine the impact response of a laminate repaired at different locations. The impact point at the edge of the patch has a detrimental effect on the repaired laminate. The impact point vertical position near the bottom hole edge of the parent plate in the scarf‐repaired case harms the impact resistance of the laminate.Highlights The low‐velocity impact response of bonded versus scarf‐repaired laminates was compared. Bonding repairs provide superior impact resistance to damaged laminates than scarf repairs. The risk of adhesive failure in scarf repair is significantly higher than in bonded repair. The relative position of the damage (repair) to the impact point critically influences the impact response. Impacts near the edge of the initial damage hole can cause severe damage to scarf‐repaired laminates.

Low speed impact on sandwich beam with flexible core and face sheets reinforced with FG-CNTs

Purpose The purpose of this study is to model the theory of the low-velocity impact (LVI) process on sandwich beams consisting of flexible cores and face sheets reinforced with functionally graded carbon nanotubes (CNTs). Design/methodology/approach A series of parameters derived from molecular dynamics are used to consider the size scale in the mixture rule for the combination of CNTs and resin. A procedure involving the use of the first-order shear deformation theory of the beam is used to provide the displacement field of the sandwich beam. The energy method and subsequently the generalized Lagrange method are used to derive the motion equations. Due to the use of Hertz’s nonlinear theory to calculate the contact force, the equations of motion are nonlinear. Validation of the problem is carried out by comparing natural frequencies with other papers. Findings The influence of a series of parameters such as CNTs distributions pattern in the face sheets, the influence of the CNTs volume fraction and the influence of the core thickness to the face sheets thickness ratio in the issue of LVI on sandwich beams with clamped-clamped boundary conditions is investigated. The result shows that the type of CNTs pattern in the face sheet and the CNTs volume fraction have a very important effect on the answer to the problem, which is caused by the change in the value of the Young’s modulus of the beam at the contact surface. Changes in the core thickness to the face sheets thickness ratio has little effect on the impact response. Originality/value Considering the important application of sandwich structures in vehicles, aviation and ships, in this research, sandwich beams consisting of flexible core and CNTs-reinforced face sheets are investigated under LVI.