Impact Energy Absorption Research Articles

Influence of projectile shape on ballistic behavior of 3D shallow straight-joint woven fabrics

This study investigates the influence of projectile shape on the ballistic behavior of 3D shallow straight-joint woven fabrics (3DSSWFs). Utilizing a series of numerical simulations, we analyze the impact resistance and energy absorption capabilities of 3DSSWFs when subjected to projectiles of varying geometries. The projectile setup includes spherical, conical, flat, and hemispherical projectiles to comprehensively assess their effects on fabric deformation, damage mechanisms, and overall ballistic performance. Results indicate that projectile shape significantly affects the penetration resistance and failure modes of 3DSSWFs. Spherical projectiles tend to cause extensive delamination and localized fabric failure, whereas conical and flat projectiles exhibit different interaction dynamics, influencing the energy dissipation patterns within the fabric matrix. The findings of this study provide critical insights into the complex relationships between projectile geometry and fabric response in 3DSSWFs. By elucidating the role of projectile shape in determining the ballistic limit, energy absorption capacity, and failure mechanisms, this research contributes to the broader understanding of impact dynamics in advanced textile structures.

Study on Mechanical and Microstructural Evolution of P92 Pipes During Long-Time Operation

To investigate the mechanical properties and microstructure evolution of P92 steel during long-term service, the operated P92 main steam pipes from the first ultra-supercritical units in China were sectioned into samples representing various service durations and stresses (0# (as-received state, 1# (82,000 h, 67.3 MPa), 2# (85,000 h, 78.0 MPa), and 3# (100,000 h, 80.3 MPa)). Thereafter, a comprehensive assessment of their mechanical properties, including tensile strength, impact, hardness, and creep resistance, as well as a detailed microstructure analysis, was carried out. The effect of stress on the aging of material properties during operation is discussed. The results show that the circumferential stress caused by the increase in the internal steam pressure can significantly promote the creep life consumption of P92 steel, resulting in the degradation of mechanical properties and the expedited aging of the microstructure. The Rp0.2 and Rm of the P92 main steam pipe at room temperature and 605 °C decreased with the service time increase, reflecting the influence of stress in operation, which is expected to be used for the residual life evaluation of P92 steel. The relationship between the impact absorption energy (FATT50), Brinell hardness, and the operating time of P92 operating pipes is non-monotonic, indicating that these parameters are not sensitive indicators of material aging due to stress. The evaluation of performance degradation in P92 operating pipes due to stress-induced aging is not reliably discernible through optical metallography alone. To achieve a thorough assessment, the use of transmission electron microscopy (TEM) is essential.

Modelling and optimisation of the structural performance of lightweight polypropylene fibre-reinforced LECA concrete

Lightweight fibre-reinforced concrete integrates the advantages of lightweight aggregates with the strength-enhancing properties of fibres, resulting in a lighter composite with enhanced impact and mechanical performance. However, achieving an optimal balance between structural weight, and performance remains a challenging endeavour. This study investigates the mechanical properties, impact energy absorptions, flexural toughness, and crack resistance of lightweight fibre-reinforced concrete with the coarse aggregate entirely replaced with lightweight expanded clay aggregate (LECA). Concrete mixes containing 0 %, 0.5 %, 0.75 %, and 1.0 % Polypropylene fibre (PPF) and 10 % micro-silica were experimentally investigated. Predictions for concrete mixes with up to 2 % PPF were made using regression models developed from experimental data. The experimental and predicted results were analysed using response surface methodology. The findings reveal significant enhancements of up to 300 % and 570 % in toughness indices I5 and I10 at 1 % PPF, coupled with a 55.4 % increase in residual strength. Furthermore, an optimised slab thickness of 47 mm containing 1.73 % PPF yielded optimal impact energy absorption of 680 J and 2384 J and crack resistance of 3823 MPa and 16279 MPa at service and ultimate loading, respectively. These metrics represent improvements of 4.8, 15.2, 37, and 56 times, respectively, compared to the control samples. These substantial advancements highlight the potential of lightweight fibre-reinforced LECA concrete in engineering applications where balancing impact energy absorption, crack resistance, and structural weight is crucial. This innovative approach promises a transformative impact on the construction industry, paving the way for more efficient and resilient infrastructure.

Frontal Impact Energy Absorbers for Passenger Cars.

Road accidents cause considerable losses to road users and to society. The steady increase in the number of vehicles leads to increased traffic volume. Therefore, there is a real need to improve passenger safety by developing passive safety systems. This article presents the results of experimental tests of structures absorbing kinetic energy, which could be used in the front section of a vehicle in order to reduce the consequences of passenger car head-on collisions. A number of crash tests of selected structures were conducted under various load conditions. An analysis was carried out of parameters enabling the authors to assess the level of energy absorption by the absorbers made, and compare these to absorbers available on the market. The tests carried out made it possible to determine energy absorption capability of the crash boxes prepared and to identify a structure exhibiting the most advantageous properties from the point of view of its prospective use. Of all of the absorbers analysed, in the context of energy absorption, it was the absorber made of glass-fibre-reinforced polyphenylene sulphide that produced the most advantageous results. Nonetheless, favourable results were obtained for all of the structures tested.

Effect of heat treatment on microstructure and mechanical anisotropy of direct energy deposited Ti-6.0Al-2.5Nb-2.2Zr-1.2Mo alloy

Ti-6.0Al-2.5Nb-2.2Zr-1.2Mo alloy (Ti-6321) exhibits excellent corrosion resistance and impact toughness, which can be used as a deep-sea pressure-resistant hull. However, the alloy tends to have high strength but low plasticity, poor impact toughness, and anisotropic mechanical properties by fabricating by direct energy deposition (DED) technology. In order to improve the impact toughness of DEDed Ti-6321 alloy while reducing its anisotropy of mechanical properties, this study manipulates the microstructure and mechanical properties of the alloy through heat treatment. The research finds that with the increase of the single-stage annealing temperature within the (α+β) two-phase region, the width of the α phase increases, the Ultimate Tensile Strength (UTS) remains essentially unchanged, the Yield Strength (YS) decreases, and the impact absorption energy significantly improves. For double annealing heat treatment at two-phase region, temperature increase at the first-stage annealing enlarges the width and decreases the aspect ratio of the primary α phase. Leading to the decrease of the UTS & YS and increase of the impact absorption energy, with a conversely tendency at 1000 °C. The increase in the second-stage annealing temperature raises the size and volume fraction of the secondary α phase, causing the alloy's UTS and YS to initially rise then fall, with a slight increase in impact absorption energy. The anisotropy in the mechanical properties of DEDed Ti-6321 alloy mainly addressed from the different distribution of α phase orientations at different loading directions, and can be eliminated through sufficient β single-phase zone annealing.

Improving the Impact Resistance of Anti-Ram Bollards Using Auxetic and Honeycomb Cellular Cores

Security is a crucial matter, and when it comes to road safety, barriers are increasingly needed to protect assets and pedestrians from intentional and accidental vehicular impacts. Hollow steel tubes are commonly used to produce bollards; however, their impact resistance and energy absorption are limited. Hence, the aim of this study is to investigate whether the addition of honeycomb and auxetic cellular cores can improve the energy absorption and protection level of existing bollards. Hollow bollard, a honeycomb–core bollard and an auxetic-core bollard were numerically modeled and tested (using Simulia Abaqus software, version 2019) against the impact of M1-class vehicles (of 1500 kg mass) at five different speeds (following PAS 68:2013 British standard). Hence, 15 cases/numerical models were considered, with 5 cases for each bollard type. The results revealed that the addition of an auxetic cellular core to the bollard system could increase its energy dissipation by 52% compared to the hollow steel bollard. Moreover, the proposed auxetic anti-ram bollard system was capable of stopping an M1-class vehicular impact of 64 km/h compared to only 32 km/h when using a hollow steel bollard. To the authors’ knowledge, the use of an auxetic core, explicitly for anti-ram bollards, can be considered the novel part of this research.

Absorption of Impact and Shear Energy by Crystal Lattices of Mechanically Activated Inorganic Substances: A Review

Absorption of Impact and Shear Energy by Crystal Lattices of Mechanically Activated Inorganic Substances: A Review

The impact protection behavior of UHPC composite structure on RC columns

In order to prevent the reinforced concrete (RC) structures from being damaged under the overload impact, a new type of composite structure—ultra-high performance concrete (UHPC)–Bio-inspired honeycomb column thin-walled structure (BHTS) was designed in this paper. A scale model with a scaling factor of 1:10 was made. The experimental tests and numerical simulations of RC column and UHPC composite structure were carried out. By comparing the impact force, displacement, shear force, bending moment and energy absorption, the protective effect of the UHPC-BHTS composite structure on RC columns under lateral impact load was evaluated. Then, the failure process of RC column was analyzed, the UHPC-BHTS composite structure absorbed 76.42% of the impact kinetic energy under the higher energy input condition, the shear failure with large damage to the RC column can be converted into bending failure with small damage. At the same time, a new damage assessment method was used to evaluate the RC column. The results show that the RC column with UHPC-BHTS composite structure can effectively protects the RC column structural integrity under impact. The design and modeling methods in this research can provide a useful reference for anti-collision design in practical engineering.

Influence of nano industrial waste and short coir fiber filler on hybrid inter and intra yarn bio fiber composites

Bio-polymer composites are emerging as a feasible substitute for conventional polymers in various major fields of applications. In the current research, the impact of hybridization of inter and intra-woven natural engineering fibers namely, brown flax, white flax, and jute of different amalgamations along with commingled SCF and novel nano IW filler has been studied. The composites are manufactured by hand layup process and physical and thermomechanical characteristics of the composites are experimentally studied. The composites mingled with IW filler demonstrated better dimensional stability and mechanical properties such as maximum tensile strength of 36.74 MPa, bending strength of 82.53 MPa, and hardness of 84.89 D compared to other composites. However, elastic and flexural modulus are maximum for composite without any filler. The composites mingled with SCF filler demonstrated the highest impact strength, energy absorption, and elongation. Thermogravimetric analysis and thermal conductivity study demonstrated that the composite with SCF filler exhibited better thermal stability and thermal resistance than the other hybrid composites. Fourier transform infrared spectroscopy study confirms the interaction of hydrogen bonds with different polymers, matrices, and fillers. It is established that the weaving pattern and the filler types greatly influences the mechanical and thermal characteristics of the composites. Filler addition and fabric hybridization optimizes the catastrophic failures and enhances the thermal stability, hence becoming more suitable for small interior structural components in aerospace and automobile applications.

Effective Press Folding Line Process as Producing Smart Intersection in Square Steel Pipe Structures by Using Crushed Cross Section Compactly

As a cross section of square steel pipe is crushed, the upper plate and the lower plate deform inward, and the side plates deform outward from the original square cross section shape. When the press folding line process as deformation induction is applied, the upper plate and the lower plate keep flat, and the side plates are compactly folded inward. This deformation pattern is safe without causing any harm to the surrounding area, and makes it possible to improve impact energy absorption performance by folding side plates as overlapping. Moreover, square steel pipe structures include places as pipes intersect and places to avoid interference with other parts (piping, wiring, fork claws, etc.). In such cases, the current method is to create an opening by cutting off. At that time, the structural strength will decrease, so reinforcing materials are often installed as a countermeasure. On the other hand, if the opening is processed by laterally impact crushing using the press folding line process proposed in this paper, a crushed part will remain, suppressing the decrease in structural strength, and this can be handled without adding reinforcing material to be a smart intersection. This paper shows the findings based on experimental data, FEM (Finite Element Method) results on processing conditions for inward deforming side plates of square steel pipes and evaluation of impact energy absorption performance in laterally impact crushing.

Flat silk cocoons: A candidate material for fabricating lightweight and impact-resistant composites

The utilization of silk cocoons in the production of lightweight and tough composites has been gaining increasing attention. However, the limited applications of normal silk cocoons (NSC) are attributed to their small size and irregular shape. To overcome this deficiency, flat silk cocoons (FSC) with a similar structure and controllable size were prepared. Next, we systematically characterized and compared the microstructures, morphologies, compositions, thermal properties, and mechanical properties of FSC with NSC. Subsequently, FSC was successfully utilized to fabricate a novel silk fibroin fiber reinforced sericin matrix composite (HPFSC) using a hot pressing method, followed by the analysis of its microstructure evolution, mechanical properties, failure modes, and theoretical modeling. This composite has outstanding mechanical properties including hardness, modulus, and strength. HPFSC has a relatively low density of ~1.3 g/cm3, whose absorbed impact energy can reach a maximum value of 11.1 J/mm, exceeding that of most engineering materials, such as aluminum alloy, ceramics, glass, and carbon fiber composites. The exceptional performance of HPFSC can be attributed to the reduced porosity, enhanced bonding between silk fibroin fibers facilitated by sericin, and their structural transformation. This study offers valuable guidance for the fabrication of lightweight and impact-resistant composites using flat silk cocoons.

Behavior of zero cement reinforced concrete slabs under monotonic and impact loads: Experimental and numerical investigations

Currently, there is a shift toward the use of low-carbon construction materials to reduce global carbon dioxide emissions. Zero-cement concrete (ZCC) synthesized from alkaline activated fly ash (FA) is a promising alternative for Portland cement in the construction industry to reduce global CO2 emissions, increase the consumption of waste materials, and save energy. A substantial amount of research on the impact load behavior of ordinary reinforced concrete (RC) structural components has been conducted. However, investigations on the behavior of zero cement concrete (ZCC) slabs under impact loads have not been reported. In this work, twenty simply supported two-way flat reinforced fly ash ZCC slabs (including two normal concrete (NC) slabs as reference samples) were tested under monotonic and impact loads. The test samples were categorized into eight groups on the basis of various parameters. Twelve RC slabs (1 NC and 11 ZCCs) were prepared for repeated impact tests, and eight slabs (1 NC and 7 ZCCs) were prepared for monotonic loading tests. Various parameters were investigated herein, including slab thickness, bar spacing, molarity concentration of alkali activators, hammer height, and hammer mass. Nonlinear finite element models were also developed and validated by using ABAQUS software for additional parametric study purposes. The results revealed that the behavior of ZCC slabs is approximately similar to that of NC slabs. The results also revealed that an increase in the ZCC slab thickness, reinforcement ratio, hammer height, and hammer mass has a noticeable effect on the dynamic response of the slab. However, increasing the molarity concentration of alkali activators has clearly a slight influence on the impact loadtime history. When the slab thickness was increased or the bar spacing was reduced, the static and impact energy absorption capacities were increased by 1.5 and 2.0 times, respectively. For impact load tests, the damage degree, penetration, and cracking pattern at failure were approximately typical for all test samples at the first hit except when the hammer mass and impact height were changed. For the samples subjected to monotonic loading, a flexural response was observed for almost all the slab samples at the first loading stage, and cracking started from the midpoint of the slab and propagated toward the slab edges; ultimately, punching shear failure was observed.

EXPLORING THE EFFECTS OF STITCHING PROCESS ON THE MECHANICAL PROPERTIES OF THREE- DIMENSIONAL (3D) STITCHED UNIDIRECTIONAL COMPOSITES

The stitching process has obvious effects on the out- of- plane mechanical properties of composites such as impact damage mechanism or impact energy absorption. However, the effects on the in- plane mechanical properties of composites have been under discussion and need to be clarified. In the previous studies, tensile, shear and bending behaviors of 3D stitched biaxial woven carbon composite were investigated. The unidirectional carbon woven fabrics constitute the significant part of raw materials in the composite industry. For this reason, the research study was expanded to examine the in- plane mechanics of 3D stitched unidirectional carbon woven composites. In this study, the unstitched and 3D stitched unidirectional woven carbon composites were manufactured and tested under the shear, tensile and bending loads. While the stitching process improved the tensile and shear modulus of composite, it could not create the significant difference in the bending behavior. The highest module and maximum stress values were obtained in the tensile test. The bending and shear test results follow them, respectively. Moreover, it was proven that the fabric architecture of stitched composite layer has the substantial effect on the tensile properties of 3D stitched composite.

Low-velocity impact response and damage mechanism of cosine function cell-based lattice core sandwich panels

This study aims to investigate the impact response and damage mechanism of cosine-function cell-based (CFCB) lattice core sandwich panels. Several low-velocity impact tests were conducted to explore their advantages in impact resistance by comparing them with traditional body-centered cubic (BCC) lattice-core sandwich panels. The impact response and deformation patterns of CFCB lattice core sandwich panels with two different faceplate materials (aluminum alloy and carbon fiber reinforced plastic composite) were experimentally investigated. The CFCB lattice core sandwich panels exhibited higher impact resistance and energy absorption capacity than their BCC lattice core counterparts. Furthermore, sandwich panels with aluminum alloy faceplates provided better impact resistance capacity than those with CFRP faceplates. Subsequently, several numerical models were developed to explore the deformation mechanisms and energy absorption characteristics of CFCB lattice core sandwich panels. In addition, the effects of the core structural parameters on mechanical performance were numerically investigated. Results indicated that increasing the cell rod diameter and/or reducing the cosine period length could decrease the indentation depth and enhance crush force efficiency. Finally, based on the principle of minimum potential energy, a theoretical model was developed to predict the initial peak load of CFCB lattice core sandwich panels with isotropic faceplates. This study aimed to explore the impact response and provide design guidance for CFCB lattice core sandwich panels.

Mechanical behaviors of composite auxetic structures under quasi-static compression and dynamic impact

This paper presents a low-velocity impact study on two types of structures, namely (1) planar multi-cellular auxetic structures (AUS) composed of multiple re-entrant cell structures made of unidirectional carbon fiber reinforced composite (CFRP) laminate, and (2) sandwich CFRP-AUS structures (Al/CFRP-AUS), whereby the CFRP-AUS was sandwiched by aluminium plates. The experimental results reveal the mechanical behaviors of CFRP-AUS under quasi-static compression and drop hammer impact loading, and the mechanical behavior of Al/CFRP-AUS under drop impact loading. The energy absorption of the CFRP-AUS associated with quasi-static compression is greater than that associated with drop hammer impact, which is consistent with the observed differences in failure modes. The impact energy absorption capacity of the Al/CFRP-AUS is slightly higher than that of the CFRP-AUS due to the interaction between the plates and the AUS. The corresponding finite element analysis was performed and the drop hammer impact of the multi-layered CFRP-AUS was predicted. In conclusion, the CFRP-AUS structures have good energy absorption capacity during impact loading, and the known complex mechanical behaviors of deformation, failure and contact can provide guidance for the design of energy absorption box and bumper in engineering application.

The study on the wood candidates for the impact limiter of a spent fuel cask

The nuclear fuel transportation package is meticulously designed to enclose radioactive materials, guaranteeing containment even after undergoing a free-drop impact test and considering potential accident situations to prevent radioactive leakage. The impact limiters attached to the transport cask are engineered to absorb impact energy. Wood, renowned for its strong energy absorption capacity, is often specified as the core material within impact limiters. It is crucial to accurately determine the wood material employed in the impact limiter. This study carried out crushing experiments on various common wood materials to obtain stress versus strain data for the selection of the appropriate wood material. Indicators such as density, crushing strength, and densification strain are utilized to assess the suitability of wood as the filler material of the impact limiter. Paulownia wood is chosen based on density, the appropriate energy absorption value per unit volume, and response acceleration. The dispersity of the strengths of Paulownia wood is taken into account with the weakest-link models. The finite element method is adopted to precisely design and verify the impact limiter. The arrangement of the glulam wood is designed to balance the energy absorption in hypothetical accident conditions. Finally, tests on the application of the impact limiter in the transportation cask were conducted to validate the proper design of the impact limiter. This study can offer reference and data support for the research on wood filler materials.

Enhanced Impact Strength of Ultra-High-Performance Concrete Using Steel Fiber and Polyurethane Grout Materials: A Comparative Study

This study examined the impact properties of ultra-high-performance concrete (UHPC) mixtures with steel fiber (SF) and retrofitted with polyurethane (PU) grouting using repeated drop-weight tests. Micro-steel fiber was added to UHPC mixes from 0 to 3% Vf, and PU grouting overlays of 5 mm, 10 mm, and 15 mm were applied. Digital image correlation (DIC) was used to analyze failure modes. The results showed significant impact durability and energy absorption improvements with increased SF content and thicker PU overlays. UHPC-15PU exhibited 363% and 449% higher first crack and failure strengths than UHPC-5PU. DIC analysis confirmed the failure patterns of the U-shaped UHPC specimen under impact load conditions.

Effect of printing temperature on the mechanical properties of 3D printed polyphenylene sulfide (PPS) during simple and repeated impact tests

AbstractFused filament manufacturing (FFF), also known as 3D printing, is one of the most commonly used additive manufacturing techniques for creating high-quality materials. This process demonstrates the intricacies and challenges involved in choosing appropriate manufacturing parameters to achieve the desired outcomes. Among these critical parameters is the nozzle temperature, which can be adjusted to enhance the mechanical properties of the 3D-printed Polyphenylene Sulfide (PPS) parts. The main objective of this study is to investigate the influence of the printing temperature on the mechanical properties and failure characteristics of 3D printed polyphenylene sulfide (PPS) parts during impact testing. To do this, a series of simple and repeated impact tests were carried out on printed PPS samples in the nozzle temperature range (320–350 °C). CHARPY tests were carried out on the samples manufactured with different sequences for the optimal orientation of the filaments. Furthermore, the impact energy absorption capacity and the induced damage as a function of nozzle temperature were evaluated. CHARPY test results showed that samples with stacking sequence (0/0) had the best impact resistance and specific absorbed energy (SEA). This sequence, printed horizontally, was used to test different print temperatures in single and repeated impact tests. Furthermore, the results indicated that samples printed with a nozzle temperature of 340 °C exhibited higher CHARPY impact resistance and specific absorbed energy (SEA), with a percentage difference of 45.57%, 41.95% and 44.21% compared to samples printed with nozzle temperatures of 320 °C, 330 °C and 350 °C respectively. For repeated impact tests, the results also show that samples printed with a nozzle temperature of 340 °C have a higher initial energy absorption rate and a greater number of impacts before complete failure of the sample. This result proves also that the changing of nozzle temperature does not have a significant effect on the induced damage after CHARPY and repeated impact.

Numerical study of composite structures behavior under ballistic impacts

The aim of this paper is to introduce a finite element study of the behavior of composite plates subjected to ballistic impacts. The work studies different configurations of laminated composite structures, with and without reinforcements, subjected to high-speed projectile impacts (400-1000 m/s). The investigation focuses on the response of different composite materials' stacking sequences, as well as the impact of epoxy carbon reinforced with carbon nanotubes and the behavior of hybrid sandwich structures made of Kevlar epoxy and glass epoxy. The purpose is to develop a strategy of composite material damage modelling, identify the effects of multi material hybridization, and the influence of reinforcement by carbon nanotubes, on the structures' resistance to ballistic impacts. Numerical simulation provides a detailed description of plate damage. Results show that composite plates with 2% carbon nanotubes (CNT) displays a better impact energy absorption compared to 1% CNT and plates without CNT. The study also revealed the hybridization sequences offering the greatest energy absorption.

Characterization and optimization of TIG welding parameters for AISI 304 and AISI 316 stainless steel dissimilar joints

This study explores the impact of tungsten inert gas (TIG) welding parameters on the mechanical properties and microstructure of dissimilar welds between AISI 304 and AISI 316 austenitic stainless steels. Given the growing industrial demand for these materials, the research focuses on optimizing welding current, shielding gas flow rate, and voltage to enhance tensile strength, hardness, and impact toughness. Using the L9 orthogonal array based on Taguchi’s methodology, the experiments revealed that Relatively highs currents and voltages significantly improved the ultimate tensile strength (up to 673.67 MPa) and impact energy absorption (up to 36.5 J). Microstructural analysis indicated refined grain structures in the heat-affected zones, with pronounced grain growth in AISI 316 due to its thermal sensitivity. The micro-hardness analysis revealed that the highest hardness occurred in the HAZ of AISI 304, with samples 5 and 6 exhibiting the optimal hardness profile, reflecting the most favorable welding parameters. The study concludes that a current range of 80-90 A and a voltage range of 10-11 V and a shielding gas flow rate of 12-16 L/min provide optimal welding conditions, offering robust guidelines for industrial applications requiring high-performance dissimilar welds.