High Impact Energy Absorption Research Articles

Role of fibre weight fraction on low-velocity impact characteristics of abaca fibre reinforced bio-composites

This work involved an experimental study on Abaca fibre bio-composites subjected to a low-velocity impact test at 2.42 m/s to study the effect of fibre weight fraction on the impact performance. The abaca fibre reinforced composite (AFRC) specimens were fabricated with a 10% increment of fibre, varying from Wf = 20% to 50%, and their impact properties compared with each other. The impact properties such as force-time history, energy-time history, Coefficient of Restitution (CoR), Energy Loss Percentage (ELP) and Energy Absorption Ratio (EAR) were studied. A significant change in impact force and energy absorption was found as the fibre content increased in the composite. The findings show a good relationship between fibre weight fractions, composite laminate stiffness, impact load and total absorbed energy. The experimental results of the impact test show that the composite specimen with Wf = 40% has high impact energy absorption capacity with 4. 09 J 92.94 N and 4.09 J, EAR of 39.94%, CoR of 0.77 and ELP of 40.04%. Low fibre weight fraction composite has shown brittle failure, and high fibre weight fraction has shown ductile behaviour. Scanning electron microscopy (SEM) based study was used for post-impact damage analysis.

Effect of ethylene vinyl acetate foam-graphene composite material on the mechanical properties of sports footwear

Ethylene vinyl acetate (EVA) foam is widely used as midsole material in athletic footwear due to its lightweight and cushioning properties. However, EVA foam suffers from low mechanical strength, abrasion resistance, and fatigue resistance. Reinforcing EVA foam with graphene nanoplatelets is a promising approach to improving its mechanical performance for footwear applications. This study investigated the effect of 0.1–1 wt% graphene nanoplatelets on the properties of EVA foam composites relevant to midsole performance. The results showed that 0.1–0.2 wt% graphene provided optimal reinforcement, exhibiting 33–40% higher impact energy absorption, 50–60% lower compressive stiffness, 30% higher flexural stiffness, and up to 40% lower abrasion volume loss. Under simulated use conditions, the composites demonstrated higher energy return and fatigue resistance. The graphene nanoplatelets acted as effective reinforcements within the EVA foam by improving stress transfer, inhibiting crack propagation, and shielding the foam surface. The findings indicate that reinforcing EVA foam with small amounts of graphene nanoplatelets can develop midsole materials with enhanced mechanical performance for athletic footwear.

Quasi-static compressive and cyclic dynamic impact performances of vat photopolymerization 3D printed Al2O3 triply periodic minimal surface scaffolds and Al2O3/Al hybrid structures: Effects of cell size

In this study, Al2O3 triply periodic minimal surface (TPMS) scaffolds with cell sizes of 5 mm, 8.5 mm, and 12 mm were prepared by vat photopolymerization 3D printing, and Al2O3/Al ceramic-metal hybrid structures were subsequently obtained by the metal infiltration of AlSi10Mg. To investigate the influence of cell size on the mechanical properties of vat photopolymerization 3D printed Al2O3 TPMS scaffolds and Al2O3/Al hybrid structures, quasi-static compression and dynamic impact experiments were conducted, and the failure modes during experiments were discussed. It was shown that the quasi-static compression and dynamic impact properties of Al2O3 TPMS scaffolds gradually decreased with the increase in cell size, the compression strength decreased from 15.2 MPa to 8 MPa and the impact strength decreased from 37 MPa to 11 MPa, respectively, which was related to the stress transfer ability of the single cell. In contrast, the effects of cell size on the performance of Al2O3/Al hybrid structures were opposite. When the cell size increased, the quasi-static compression performances of the Al2O3/Al hybrid structure were greatly improved, and the compression strength increased from 175 MPa to 250 MPa. The impact resistances of the Al2O3/Al hybrid structure were further studied. The highest impact strength of the Al2O3/Al hybrid structure was 290.74 MPa. With the increase in cell size, the impact resistance of the Al2O3/Al hybrid structure had a gradual improvement trend. Under the cyclic impact, the Al2O3/Al hybrid structure showed a high impact strength and energy absorption capacity, which was mainly related to the metal phase content around the cell, i.e., the coherence of the metal phase. This study is believed to give help for the structural design of ceramic scaffolds and ceramic-metal hybrid structures.

Enhancement of natural fiber-reinforced plastics by polyester and seaweed waste fibers

A bio-based composite material made from wastes from Posidonia oceanica (PO) and sugar cane polyester (SCPES) has been developed in the current work. DSC and TGA have been used to investigate the thermal deterioration of composites, and the results demonstrate an improvement. Using dynamic mechanical analysis (DMA) data, it has been found that the storage modulus (G) increases significantly as the Posidonia oceanica concentration rises. There has been a 60 % increase in stiffness in 40 % composites compared to unfilled materials in tensile test results. Flexural modulus of polyester, when unloaded is more than twice that of polyester, when fully loaded. In addition, Shore D hardness as well as Charpy impact test findings reveals that HDPE's intrinsic high impact energy absorption is intact in HDPE-PO composites, confirming this improvement in mechanical properties. As a result of the low water absorption rate (less than 8 %) and the long immersion time, these composites are assured to preserve their dimensional stability.

Epoxidized and Maleinized Hemp Oil to Develop Fully Bio-Based Epoxy Resin Based on Anhydride Hardeners

The present work aims to develop thermosetting resins using epoxidized hemp oil (EHO) as a bio-based epoxy matrix and a mixture of methyl nadic anhydride (MNA) and maleinized hemp oil (MHO) in different ratios as hardeners. The results show that the mixture with only MNA as a hardener is characterized by high stiffness and brittleness. In addition, this material is characterized by a high curing time of around 170 min. On the other hand, as the MHO content in the resin increases, the mechanical strength properties decrease and the ductile properties increase. Therefore, it can be stated that the presence of MHO confers flexible properties to the mixtures. In this case, it was determined that the thermosetting resin with balanced properties and high bio-based content contains 25% MHO and 75% MNA. Specifically, this mixture obtained a 180% higher impact energy absorption and a 195% lower Young's modulus than the sample with 100% MNA. Also, it has been observed that this mixture has significantly shorter times than the mixture containing 100% MNA (around 78 min), which is of great concern at an industrial level. Therefore, thermosetting resins with different mechanical and thermal properties can be obtained by varying the MHO and MNA content.

Development and characterization of sandwich panels for thermal insulation in a cold storage chamber

Sandwich composites are materials that have superior properties including low weight, high impact energy absorption and high thermal insulation features, compared to conventional materials. In this study, four different sandwich samples were explored for use in cold storage chambers. The composites were created using an injection molding process with polyurethane foam as the core and different materials (glass fiber reinforced polyester, galvanized steel, aluminum sheets and crimped aluminum) as face materials. Morphological, physical and mechanical properties were evaluated. An inexpensive and nondestructive method was used to determine the thermal behavior of the sandwich panels, and the surface temperature evolution was thermally monitored during the tests. In general, results showed that polyurethane had a homogeneous distribution of size and shape with closed cells, which can improve the retention of the insulating gas. Additionally, the compressive strength of polyurethane within the composites exhibited typical values to be used in specific applications. Thus, the sandwich with galvanized steel exhibited lower flexural strength, which provides more freedom in panel design. The overall heat transfer coefficient of the panels in the form of cubes presented values below the maximum limit requested by ABNT NBR-15457. Finally, the composite galvanized steel/polyurethane/galvanized steel achieved the best performance for use as a thermal insulation material in a cold storage chamber.

Hybrid polymer composites with enhanced energy absorption

This paper presents the influence of the type and structure of reinforcement, on the epoxy resin matrix polymer composites mechanical and ballistic properties. Aramid, basalt, glass fabrics and their hybrid systems were used as reinforcement. Impact strength according to Izod and "falling arrowhead", flexural strength and structure of the obtained composites were tested. The specific gravity was also determined. The aramid-glass hybrid composites showed high flexural strength (397 MPa) and Young's modulus (21 GPa). However, aramid-basalt composites had high impact strength (116 kJ/m2) and impact energy absorption (45 J).

A Simplified Method for Evaluating the Dynamic Response of the Metal Sandwich Structure under Explosion Load

The metal sandwich structure is characterized by light weight, high stiffness, and high-impact energy absorption capacity, which is considered a good alternative protective structure in explosion scenarios. In this paper, four design forms of the metal sandwich structure are introduced, and the dynamic response of the metal sandwich structure under explosion load is researched. Then, a new analytical method is proposed to predict the dynamic response of the metal sandwich structure under explosion load, and numerical simulations are carried out to verify the accuracy of the proposed analysis method. The proposed analytical method is designed for aerial explosions without considering the fluid–structure interaction. In addition, a series of parameter studies are carried out, including the influence of the face sheet aspect ratio, the core height, and the thickness of the face sheet and core on the dynamic response of the sandwich structure under explosion load. The research in this paper has reference value for the anti-explosion design of the metal sandwich structure and will provide a useful reference for the design and optimization of the metal sandwich structure.

Influence of crumb rubber on the response of concrete beams against low velocity impact

High impact resistance and energy absorption capacity are desirable characteristics of concrete for several structural applications such as roadside barriers, bridge columns, rockfall protection barriers, and industrial buildings. Crumb rubber has been proven to enhance these characteristics of concrete. In past, numerous experimental investigations have been performed to study the mechanical properties of rubberized concrete. However, a detailed inspection of rubberized concrete under low velocity impact is still lacking. Also, the design guidelines for the employment of crumb rubber in concrete have not been explored. In the current study, the influence of partial replacement of sand with crumb rubber on the impact response of concrete has been studied. Concrete mixes with different proportions of sand replacement (5–30% by volume) have been prepared. The impact tests are conducted using drop impact test setup on concrete beams of dimension 500 mm × 100 mm × 100 mm. The specimens are subjected to an impact of 6 kg mass from an elevation of 500 mm. The results reveal that the replacement of sand with crumb rubber enhances the flexibility, energy absorption capacity, and peak impact force. Although, a curtailment in the compressive strength, elastic modulus, and split tensile strength is observed. Moreover, the microstructural properties of rubberized concrete are also investigated using SEM (Scanning Electron Microscopy), and tentative design guidelines are proposed for selecting an optimum percentage of crumb rubber in concrete.

Dynamic mechanical properties of the selective laser melting NiCrFeCoMo0.2 high entropy alloy and the microstructure of molten pool

To improve the dynamic mechanical properties of the selective laser melting (SLM)-NiCrFeCoMo0.2 high entropy alloy (HEA), dynamic impact experiments were carried out on this alloy with different characteristic molten pools. Melt pool structures of different special sizes can be obtained by adjusting the laser power and scanning speed during the SLM process. In this work, the split-Hopkinson pressure bar (SHPB) is used to conduct dynamic impact on the SLM-NiCrFeCoMo0.2 HEA samples with different molten pool size. The X-ray diffractometer (XRD), the scanning electron microscope (SEM), the electron probes micro-analyzer (EPMA) and the transmission electron microscope (TEM) were used to characterize the microstructure and deformation characteristics of the of the molten pool. The SLM-NiCrFeCoMo0.2 HEA shows high impact energy absorption density and compressive strength at high strain rate. Volume energy density (VED) refers to the power delivered by the laser per unit volume of material during a SLM process, which can affect the size of the molten pool formed. Mo-rich σ phase precipitations are distributed near the molten pool boundary. In the cooling stage of the SLM process, the center of the molten pool has a faster cooling rate than the molten pool boundary, so area near the boundary stays in the temperature range where the precipitation occurs for a longer time, which is the reason why the precipitates are concentrated near the boundary. The precipitation strengthening in the SLM-NiCrFeCoMo0.2 HEA is considered by measuring the relationship between the molten pool structure and the precipitation distribution, considering the material as a composite of the precipitation dense region (PDR) and the precipitation free region (PFR), and the strength contribution of precipitation is estimated by mixing rules.

High velocity impact behavior of Hybrid composite under hydrostatic preload

The Hybridization concept creates a niche within the composite segment to customize materials for specific applications with reduced cost without sacrificing strength and durability. The composite structures develop strain during continuous operation, and any sudden impact on these preloaded parts might result in catastrophic accidents. Studying impact response during such conditions is essential in designing and developing structures. This study experimentally investigates the high velocity impact response of Hybrid (Carbon-Glass) composite under normal and hydrostatic preload conditions. Mechanical tests involving Tensile, Izod, and Charpy are conducted. High velocity impact testing is carried out with a vertical single-stage gas gun with additional provision for hydrostatic preloading. An oscilloscope with a laser source measures the initial velocity, and Photogrammetry using a high-speed camera measure the residual velocity of a projectile. The mechanical test results suggest that Hybridization resulted in a significant property enhancement. The high velocity impact resistance and energy absorption are higher for Hybrid under both normal and preloaded impact.

Mechanical Properties of Banyan Fiber-Reinforced Sawdust Nanofiller Particulate Hybrid Polymer Composite

The utilization of renewable raw materials, such as natural fiber composites, can be prioritized in the building industry as it transitions to a bioeconomy. The sustainable product can improve environmental protection; therefore, the present work is stated with the natural fibers of chopped banyan fiber reinforced with sawdust nanocellulose epoxy-based composite fabricated by hand layup process. To identify the mechanical effects of tensile strength, flexural strength, impact strength, and hardness value for five different weight ratios of chopped banyan fibers and sawdust nanofiller materials, the composite weight ratio was made with 60% of matrix phase that was fixed for all five samples and 40% of reinforcement phase in which the fibers and filler percentage can vary for five samples. The results are revealed sample E (50 g of banyan, 25 g of saw dust, 110 g of epoxy, and 185 g of laminate) given a more tensile strength of 39 MPa and a flexural strength of 34 MPa, and sample A was given a high impact energy absorption capacity of 18 Joule compared with other samples of hybrid composite; and also, the SEM morphological was used to identify the surface interaction and failure mode of this composite laminates.

Bending, buckling and linear vibration of bio-inspired composite plates

Biological composite structures with helicoidal schemes and designs have good damage tolerance and high impact energy absorption. However, the effect of redirection and the reorientation of fibers inside the matrix of helicoid structure on their mechanical performance and response have not been comprehensively examined. Therefore, this works aims to cover this topic and investigate the static, buckling and vibration behaviors of laminated composite plate structure with helicoidal orientation scheme for the first time. The formulation and analysis is based on the hypothesis of first order shear deformation theory (FOSDT) of plate. Various sets of laminates including Fibonacci sequence are considered in this study to get the optimum scheme of layer's orientation. Based on energy principle, the governing equations of motion and associated boundary conditions are derived in detail. The obtained partial differential equations of motion, in terms of displacement fields, are solved by two-dimensional differential quadrature method (2D-DQM). Verification with previous works is presented to validate the present mathematical model and solution technique. The influences of different parameters such as laminate sequence, boundary conditions, material and geometric properties on the static, buckling stability and vibration responses of composite plate are studied and discussed. It is found that the laminate sequence has a significant influence on bending, critical buckling and natural frequencies, as well as this effect varies with various aspect ratios and side to thickness ratios, and boundary conditions of the composite plate.

Comparative Study on the Mechanical Properties of Weft Knitted and Warp Fabric Reinforced Composites

Knitted fabric composites occupy a special interest in the field of engineering and materials science because of their easy to form complex component and high impact energy absorption. Mechanical tests were carried out in the course, wale and slanting directions of the knitted fabric reinforced composites. The stress-strain curves and failure modes of warp and weft knitted fabrics were investigated and compared. The test results revealed from the composite structure fabricated from warp knitted fabric shown better mechanical properties than weft knitted fabric because of the warp knitted fabric distinct by the process of overlap between the stitches that gave better resistance.

Statistical approach to optimize crashworthiness of thermoplastic commingled composites

A design of experiments analysis was developed to relate the processing conditions to the impact energy absorption capability of thermoplastic commingled composites. Based on low velocity impact test responses and statistical modeling, a factorial design was implemented to investigate the interaction of processing parameters with the polymer viscosity. The influence of thermal consolidation on materials performances were evaluated and quantified. The dataset was obtained according to the impact energy capability of carbon fiber/polyamide and carbon fiber/poly (ether-ether-ketone) commingled composites. The results identified the best combination of variables which improves crashworthiness of structural composites and leads to high impact energy absorption capabilities. The results revealed that the commingled composites crashworthiness strongly depends on the polymer yarn dispersion in the carbon fiber tow, that was identified and classified in different distribution patterns. This work represents a significant step towards manufacturing of thermoplastics composites with target structural performance.

Experimental investigation on the effect of printing parameters on the impact response of thin-walled tubes produced by additive manufacturing method

This article investigates the effect of printing parameters on the impact response of thin-walled tubes produced using the fused deposition modelling (FDM) technique under low-velocity impact energy. The specimens were produced at three different filling rates of 30, 40 and 50% with honeycomb, square and concentric patterns. Low-velocity drop tests were conducted on tubes under 125 J impact energy (load). The force-displacement histories were acquired, and the crashworthiness parameters were calculated to analyse the effect of printing parameters on the impact behaviour of the tubes. Scanning electron microscopy (SEM) was used to examine the microstructural and the morphology of the damaged area on the thin-walled tubes. The most energy-absorbing structure is determined as the square pattern specimen with a 50% filling rate, which absorbs approximately 90% (112 J) of the impact energy. The least energy-absorbing structure is determined as a concentric patterned specimen with a 30% filling rate that absorbs approximately 25% (32 J) of the impact energy. While the highest average damped specific energy value belongs to the square patterned specimen with a 40% filling rate with 9.2 J/g, the lowest average damped specific energy value belongs to the concentric patterned specimen with a 30% filling rate with 3.4 J/g value. It has been observed that the damped energy value increases with the increase in the filling rate. Depending on the patterns, the highest impact energy absorption is observed in the square patterned specimen. After the square pattern specimen, the highest energy absorption has been observed in honeycomb and concentric pattern specimens, respectively.

Investigation of Warp and Weft Knitted Fabric Acoustic Structures Derived from Garment Waste

The mechanical performance of knitted fabric was significantly affected by loop density and geometries. Knitted fabric composites occupy a special position in the field of engineering materials because of their easy to form complex components and high impact energy absorption. But Knitted fabric composites have low in-plane tensile strength because the yarns are in a loop structure in the materials. Sound insulation requirements in automobiles, manufacturing environments, and equipment, generating higher sound pressure drive the need to develop more efficient and economical ways of producing sound absorption materials. The knitted fabric based acoustic materials were produced from cut wastes from different garment industries for their sound absorption property test as per the method described in ASTM E 1050. The acoustic performance of knitted fabrics was measured by independent tube methods for sound waves of 1000-6000 Hz. It is observed that the knitted fabrics acoustic materials prepared from waste materials showed high sound absorption than woven fabrics made from the same synthetic fibers. Moreover, the test revealed that blended knitted fabric had a better sound absorption property.

Ballistic performance of green woven fabrics – A short review

The enhancement in ballistic performance for self protection acquired a great interest in the field of military or defence sector. The conventional metal or ceramic based armours from the very beginning are replaced by high performance synthetic polymers as per their exceptional strength to weight ratio and elevated heat protection characteristics. Kevlar and Aramid fibers are enormously used in manufacturing of various ballistic self protective items. But, in concern to the environmental hazards, natural fibers significantly overcome the limitations of the synthetic fibers or hybrid natural/synthetic fibers. A lot of research has already been developed by using green fibers reinforced composites owing to its high specific strength, stiffness, light weight and maximum impact energy absorption behaviour. This paper presents a short review that elucidated the significance of few novel high performance green fibers such as bamboo, curaua, jute, kenaf, etc., in the field of ballistic applications. The architecture of fibers and their configurations as well as the manufacturing processes also immensely influence the high energy absorption potential. The current paper highlights the importance of bio-influenced woven fabrics, multi layered fabrics, hybrid fabrics and the impact of polymers in manufacturing of personal protective armour, helmets or other items. The various predominant factors such as toughness, ductility, thickness and strength of composite materials are also discussed for better ballistic performance.

Free Vibrations and Impact Resistance of a Functionally Graded Honeycomb Sandwich Plate

The functionally graded honeycomb has the characteristic of light weight, low density, high impact resistance, noise reduction, and energy absorption as a kind of new composite inhomogeneous materials. It has the advantages of both functionally graded materials and honeycombs. In this paper, a functionally graded honeycomb sandwich plate with functionally graded distributed along the thickness of the plate is constructed. The equivalent elastic parameters of the functionally graded honeycomb core are given. Based on Reddy’s higher-order shear deformation theory (HSDT) and Hamilton’s principle, the governing partial differential equation of motion is derived under four simply supported boundary conditions. The natural frequencies of the graded honeycomb sandwich plate are obtained by both the Navier method from the governing equation and the finite element model. The results obtained by the two methods are consistent. Based on this, the effects of parameters and graded on the natural frequencies of the functionally graded honeycomb sandwich plate are studied. Finally, the dynamic responses of the functionally graded honeycomb sandwich plate under low-speed impacts are studied. The results obtained in this paper will provide a theoretical basis for further study of the complex dynamics of functionally graded honeycomb structures.

On the effect upon the surface finish and mechanical performance of ball burnishing process on fused filament fabricated parts

Additive manufactured parts often require post-processing to obtain the desired surface finish. In this sense, this work investigates the ball burnishing process’s applicability as a finishing method for fused filament fabricated (FFF) parts. Ball burnishing is a mechanical finishing procedure based on the plastic deformation of the treated surface that could provide significant advantages, as it is non-abrasive and does not chemically interact with the model material. Following Taguchi’s design methodology, optimal values of four burnishing parameters have been identified, and significant improvements in surface quality have been quantitatively and qualitatively proven. Mechanical performance under tensile and flexural loading, impact testing, and bending fatigue of ball-burnished samples has been compared to pristine values. Besides the enhanced surface quality of the samples, a notable finding of the study is a minimum twofold increase in the fatigue life of ball-burnished samples, as well as a higher impact energy absorption. Accordingly, this research provides experimental evidence to set ball burnishing as a novel post-processing technique for FFF parts.