Low Velocity Impact Studies Research Articles

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.

Low velocity impact study of vacuum bag infused bouligand inspired composites

AbstractThis work proposes three Bouligand‐inspired layups to enhance low velocity impact (LVI) damage resistance and tolerance of convectional aircraft composite laminates. Two Bouligand‐like (HL and HL_S) and one hybrid design layup, merging conventional and Bouligand architecture (HYB), were produced by vacuum bag infusion. Their performance under LVI, at 13.5, 25 and 40 (J), and compression after impact (CAI) tests were evaluated and compared with a conventional aircraft multidirectional layup (LS) produced under identical conditions. Results demonstrated that, especially for the higher impact energy levels, both Bouligand‐like laminates consistently outperformed all the other configurations, exhibiting higher load bearing capacity (peak load) and energy absorption. Additionally, the rough and poorly defined interlaminar region of Bouligand‐like layups have showed to delay severe damage for higher loads and energies, dissipating all (at 13.5 J) or most of the impact energy (more than 50%) through subcritical damage mechanisms. Compared with LS laminate, Bouligand‐inspired layups postponed the onset of severe damage thresholds by up to 120% in load and 66% in energy (HL laminate) while developing smaller and more localized damages. The high number of fibers aligned in the loading direction of LS laminate led to better damage tolerance.Highlights Vacuum bag infused Bouligand‐like laminates consistently demonstrated superior performance than the conventional aircraft multidirectional layup, exhibiting higher load bearing capacity and energy absorption, particularly at higher impact energy levels; The rough and poorly defined interlaminar region observed in both Bouligand‐like layups demonstrated to play an essential role in the efficiency of damage mechanisms, dissipating all (at low impact energy levels) or more than 50% of impact energy on subcritical damages, such as translaminar matrix cracking; Compared with the conventional layup, HL Bouligand‐like laminate postponed 120% and 66% load and energy severe damage onset thresholds; The high number of fibers aligned in the loading direction of LS laminate led to better damage tolerance, despite the larger damaged areas observed.

Mechanical, Wear, and Low-Velocity Impact Studies of AL7075/Basalt/Mica Particle Hybrid Metal Matrix Composite through Stir Casting Route

Mechanical, Wear, and Low-Velocity Impact Studies of AL7075/Basalt/Mica Particle Hybrid Metal Matrix Composite through Stir Casting Route

Multiscale damage and low-velocity impact study of three-dimensional woven composites

Three-dimensional woven composites address the limitation of weak interlaminar strength found in traditional laminated composites and offer superior resistance to out-of-plane impact. However, the complex material composition and structural intricacies necessitate investigation into their damage mechanisms. This study introduces novel and reliable microscale and mesoscale Representative Volume Element (RVE) models for three-dimensional woven composites, developed through advanced CT scanning and comprehensive multi-directional tensile and shear experiments. The research explores the impact of fiber volume fraction on yarn mechanical properties using the microscale RVE model, yielding precise macroscale homogenization parameters through the mesoscale RVE model. Furthermore, a macro-meso model tailored for low-velocity impact scenarios is established, significantly enhancing computational efficiency without compromising accuracy, thus providing support for further research on the impact properties of three-dimensional woven composites.

Study of low velocity impact failure responses of woven basalt fiber reinforced polymer composites using ultrasonic A, B and C scan techniques

ABSTRACTThe low-velocity impact studies to account for the variation in the number of basalt fiber layers in the through-thickness loading performance of natural fibre reinforced polymer composites are very limited. These studies are useful to understand the external and internal failure mechanisms of composites at different thicknesses. In this study, the single and multilayered basalt/polyester composite samples were fabricated, as the number of basalt fibre layers increased gradually from 1 to 9, and then low-velocity impact tests were conducted at a constant impact energy of 12 J. The impact data was measured using the LabVIEW software. Further, full-field failure or damage mechanisms of composite samples were investigated using ultrasonic A, B and C scan techniques. Failure mechanisms observed in tested samples were matrix cracking, fibre breakage, delamination, etc. However, the size and shape of failure mechanisms observed were varying with the increase in the number of layers. Samples that had a smaller number of basalt fibre layers (1–4) failed rapidly due to extensive regions of delamination and the failure mode observed was localised damage with higher regions of delamination. However, samples that had a greater number of basalt fibre layers (5–9) could withstand higher impact loads and failed progressively. The failure mode observed in these samples was mainly distributed damage with lower regions of delamination.

Low-velocity impact studies on Kevlar/Epoxy composites reinforced with carboxyl functionalized Graphene

The addition of nanoparticles as fillers improves the properties of polymer matrix composites. In this work functionalized Graphene Platelets are added to Kevlar-reinforced epoxy composites and their mechanical properties such as tensile, short beam strength and low-velocity ballistic response are evaluated. For comparison, composites prepared with 0.25, 0.5, and 0.75 wt% filler addition was compared with the condition of no filler addition. The fractured samples were examined to understand the failure mechanisms involved. The results indicated that the sample with 0.5 wt% had superior tensile, shear and energy-absorbing characteristics. A lower reinforcement weight percentage (0.25%) was unable to effectively transfer the loads while higher reinforcement percentage (0.75%) showed premature failures due to agglomeration. At the optimum reinforcement, a sufficient amount of nano-fillers passes through the matrix and the functionalization assists in good fiber–matrix adhesion through surface bonding. This leads to high interfacial properties giving high resistance to impact motion. In addition, the nanoparticles in the matrix phase help in matrix toughening giving resistance to cracking. This is evident from the micro and macroscopic fracture images which show a high fiber interaction and the least matrix failure. The lower damage area and the higher fiber pullouts also indicate the effectiveness of 0.5 wt% reinforcement.

Low velocity impact study of a sandwich beams using Ritz method and finite element modelling

PurposeThe purpose of this paper is to present an applied method to design the low-speed contact between a mass and surface of a beam using an analytical solution based on the first-order shear deformation beam theory. Also, a simulation of impact process is carried out by ABAQUS finite element (FE) code.Design/methodology/approachIn theoretical formulation, first strains and stresses are obtained, then kinetic and potential energies are written, and using a combination of Ritz and Lagrange methods, a set of system of motion equations in the form of mass, stiffness and force matrices is obtained. Finally, the motion equations are solved using Runge–Kutta fourth order method.FindingsThe von Mises stress contours at the impact point and contact force from the ABAQUS simulation are illustrated and it is revealed that the theoretical solution is in good agreement with the FE code. The effect of changes in projectile speed, projectile diameter and projectile mass on the results is carefully examined with particular attention to evaluate histories of the impact force and beam recess. One of the important results is that changes in projectile speed have a greater effect on the results than changes in projectile diameter, and also changes in projectile mass have the least effect.Originality/valueThis paper presents a combination of methods of energy, Ritz and Lagrange and also FE code to simulate the problem of sandwich beams under low velocity impact.

Experimental and Numerical Study of Low-Velocity Impact and Tensile after Impact for CFRP Laminates Single-Lap Joints Adhesively Bonded Structure.

To investigate the mechanical behavior of the single-lap joints (SLJs) adhesively bonded structure of carbon fiber reinforced polymer (CFRP) laminates under the low-velocity impact (LVI) and tensile-after impact (TAI), tests and simulations were carried out. A finite element model (FEM) was established based on the cohesive zone model (CZM) and Hashin criterion to predict the damage evolution process of adhesive film, intra- and inter-laminar of the SLJs of CFRP laminates, and its effectiveness was verified by experiments. Moreover, three different overlap lengths (20 mm, 30 mm, and 40 mm) and four different impact energies (Intact joint, 10 J, 20 J, and 30 J) are considered in the present study. Finally, the effects of different impact energies and overlap lengths on the residual strength of SLJs after impact were discussed. The results divulged that numerical results of impact and TAI processes of SLJs were in good agreement with experiment results. During the impact process, the damage of the laminates was primarily fiber and matrix tensile damage, whereas the adhesive film was damaged cohesively; the areas of damage increased with the increase of impact energy, and the normal stress of the adhesive film expanded from the edge to the middle region with the increase of impact force. The influence of LVI on SLJs adhesively bonded structures was very significant, and it is not effective to obtain a higher impact resistance by increasing the overlap length. For the tensile process, the failure mode of TAI of the SLJs was interface failure, the surplus strength of the SLJs gradually decreased with the increase of the impact energy because of the smaller overlap length, the overlap length more than 30 mm, and the low energy impact has almost no effect on the residual strength of the SLJs.

Numerical investigation of dynamic response of honeycomb sandwich panels filled with circular tubes under low velocity impact in the in-plane direction

Honeycomb sandwich structures, composed of many regularly arranged hexagonal cores and two skins, show excellent impact performance due to strong energy absorption capability under impact loads. In this paper, a numerical study of low velocity impact on honeycomb sandwich panels filled with circular tubes in the in-plane direction was performed. To calibrate the numerical model, simulation results in the out-of-plane direction are compared with the experimental ones. The numerical modelling of the drop weight test was carried out using the nonlinear explicit finite element code Abaqus/Explicit. The impact responses are presented as the contact force between the impactor and the panel versus the time. It was concluded that the filled honeycomb panel absorbs the same amount of impact energy in a shorter time than an empty one. In addition, the deflections of the front and back face-sheets are investigated. The panel degradation and the stress distribution during the crushing are also discussed.

A review on low velocity impact study of hybrid polymer composites

Fibre reinforced composites are rapidly gaining popularity in structural applications but lack of toughness limits their further growth. Fibre hybridization can be considered as a solution for toughening the composite materials which in turn increases the impact resistance. Low velocity impact in composites poses a severe threat as it causes various internal damages as well as complex mechanisms of failure, which culminate in a substantial reduction in the composite structural properties. In the aerospace industry, it is critical to study more about low velocity impact for the prediction of such damage initiation and propagation. The understanding of low velocity impact includes not just the phenomena of impact, but also other factors such as how the impact response is affected by the properties of the materials. This study presents a review on the low velocity impact study on hybrid composites, and on the various factors affecting the impact properties such as resin toughness, fibre architecture as well as hybridization. It further explores damage progression and analysis, followed by various non-destructive testing techniques and the principles employed in them.

Low-velocity impact studies on GFRP and hybrid composite structures

In this study, low-velocity impact analysis on glass fibre-reinforced polymer (GFRP) and hybrid laminates is performed through an explicit numerical analysis and relevant experiments. Hybridised composite laminates are fabricated by sandwiching the flexible Polycarbonate sheet between the glass fibre-reinforced polymer laminas. In order to analyse the improvement in the impact resistance of hybrid laminates, low-velocity impact tests are performed on both GFRP and hybrid laminates by dropping an impactor from various pre-defined heights and the absorbed energy in each case is estimated. Results from the numerical analysis are validated with experimental results. Based on the numerical and experimental analysis, variation of the absorbed energy as a function time is estimated. Furthermore, shapes of the damaged areas are also estimated using the experimental specimens. Analysis of results indicates that the hybrid laminates display better energy absorption characteristics before rupture, as compared to the GFRP laminates. For a given energy absorption weight, savings up to 30.77% are observed using polycarbonate-based hybrid composites as compared to the GFRP laminates.

A theoretical study of low-velocity impact of metal foam-filled circular tubes

Abstract In this paper, the low-velocity impact of metal foam-filled circular tubes are investigated. Based on the quasi-static method, an analytical model is developed to predict the plastic behaviors of the fully clamped metal foam-filled circular tube under the low-velocity impact. Effects of local denting and filled foam strength on the overall bending of the foam-filled tube are considered. Finite element analysis are conducted to study the dynamic response of clamped metal foam-filled circular tube. Good agreement is achieved between the analytical and numerical results. The effect of the filled foam on the dynamic response of the foam-filled tube is discussed. It is demonstrated that the present analytical model is valid to predict the low-velocity of foam-filled circular tubes.

Simulation Study of Low-Velocity Impact on Polyvinyl Butyral Laminated Glass Based on the Combined TCK-JH2 Model

In this paper, both experimental tests and numerical simulations of Polyvinyl Butyral (PVB) laminated glass pane under low-speed impact were carried out. In order to accurately predict the responses of annealed glass under low-speed impact, a constitutive model combined of the Taylor–Chen–Kuszmaul (TCK) model and the Johnson-Holmquist Ceramic (JH2) model is proposed. In order to describe the tensile damage characteristic of annealed glass, a rate-dependent TCK model is employed. The JH2 model is adopted when the glass material is under compression. The velocity and force of impactor, deflection of central point of glass pane, and the cracking pattern are studied to verify the combined TCK-JH2 model. Furthermore, the effects of the thickness of glass layer and PVB interlayer are investigated.

A low velocity impact study on press formed thermoplastic honeycomb sandwich panels

At present plywood structures are used in the loading area of utility structures. Low velocity impact studies on these structures showed cracks on its lower surface. Hence, in the current study low-velocity impact of a lighter honeycomb sandwich structure is investigated to satisfy the needs of the utility vehicle segment. To meet this objective, facing sheets are manufactured using the polypropylene matrix and glass fibers. Polypropylene honeycombs are used in the study. Depending on the experimental boundary conditions, a cross-ply laminate set up is used for the facing sheets. An impact energy of 100 J is chosen in the study. This energy caused visible failure on the plywood sample. Hence a lighter sandwich construction which can resist 100 J impact is implemented in this study. Influence of top and bottom facing sheet thicknesses on the amount of damage inflicted on its surfaces are studied. Experimental histories of absorbed energy and contact force are recorded. A finite element analysis is performed using LS-DYNA and numerical results are compared with the experimental responses. A honeycomb sandwich panel [0/90/90/0/Core/0/90/90/0] meeting the objective of the study is seen as an optimum replacement for the existing plywood structures.

Low velocity impact studies of E-glass/epoxy composite laminates at different thicknesses and temperatures

Abstract Low velocity impact experiments were carried out on E-glass/epoxy composite laminates having varying thicknesses at sub zero and elevated temperatures using hemi spherical steel impactor of 16 mm diameter with impact energies in the rage of 50–150 J. The performance of the laminates was assessed in terms of energy absorption, maximum displacement, peak force and failure behaviour. Results indicated that the effect of temperature on energy absorption of the laminate is negligible although the laminates are embrittling at sub zero temperatures. However it has influence on failure behaviour and displacement. Peak force has increased linearly with increase in laminate thickness from 5 to 10 mm. However it got reduced by 25% when temperature was increased from −20 °C to 100 °C. Based on experimental results, laminate perforation energies were predicted using curve fitting equations. Statistical analysis was carried out using Taguchi method to identify the global effects of various parameters on laminate performance and confirmed that the laminate thickness has significant influence as compared to temperature, for the studied range.

STUDY ON THE BEHAVIOR OF POLYMERIC MESH MODIFIED FERROCEMENT UNDER IMPACT LOADING

This study concentrates on determining the impact strength of polymeric fiber mesh reinforced ferrocement, under low velocity impact load. The Low-velocity impact study has been conducted on 250 mm square ferrocement slabs. The concept of using polymeric wire mesh is to reduce the corrosion of iron wire mesh, which is one of the major reasons for deterioration of ferrocement. The test procedure has been conducted on fifty four specimens including four different types of iron wire mesh and two types of polymeric mesh, with varying mesh layers from one to three. Results emphasized that the impact energy absorption increases with the raise in the number of polymeric mesh layers and the crack widths are least in amount and size compared to the specimens incorporated with iron wire mesh.

Simulation of Low Velocity Impact on CFRP Aerospace Structures: Simplified Approaches, Numerical and Experimental Results

This paper presents a study of low velocity impact on unidirectional composite specimens, a plate and an aerospace stiffened panel following the building block approach. Simplified approaches for a quick estimation of impact behavior description are used to define the impact dynamic response and the existence of delamination at coupon level, while numerical analysis models using ABAQUS/Explicit software and experimental results are described in detail and compared at all levels. Significant effort was made in the use of different types of elements and damage models for matrix cracking, fiber breakage and cohesive elements for delamination between plies of composite. The results obtained show that simplified approaches give an effective initial understanding of the impact response helping the interpretation of numerical and experimental results. In addition, the comparison of different methods of simulation demonstrated that continuum shell elements with induced cohesive elements present the most accurate results regarding the impact force, contact duration, energy absorption and damage extension.

Experimental and Simulation Study of Low-Velocity Impact on Glass Fiber Composite Laminates with Reinforcing Shape Memory Alloys at Different Layer Positions

The effects of shape memory alloy (SMA) wires on the damage behavior of glass fibers/epoxy resin composite laminates for the case of low-velocity impact are investigated experimentally and numerically. In this work, the low-velocity impact tests of SMAs/glass fibers/epoxy resin composite laminates are carried out. The elastic–plastic theory was adopted to simulate the mechanical behavior of SMA during the loading stage. The three-dimensional (3D) Hashin failure criterion is adopted in Abaqus/Explicit to model the damage initiation of composite laminates. The cohesive damage model is introduced to control the interface element and model the delamination failure. Moreover, the impact damage mechanisms of composite laminates are analyzed based on the experimental and numerical simulation results. These results show that the numerical results obtained in the present study have a reasonably good agreement with the experimental results. In addition, it is also found that impact damages are mainly caused by matrix cracks and delamination with no perforation for the case of 32-J impact energy, and impact damages are mainly caused by fibers breakage with perforation for the case of 64-J impact energy.

Experimental study of low-velocity impact on foam-filled Kraft paper honeycomb structure

Low-velocity impact tests of unfilled and foam-filled Kraft paper honeycomb are carried out to investigate the effect of foam, indenter size and location of indentation on maximum or peak force and energy absorption capability. In this study, three indenter sizes (10mm, 12mm, 15mm) and three different locations of indentation (vertical edge, double wall and single wall) were used and compared. The test results show that the foam is given a significant increment of peak force and specific energy absorption to the honeycomb structure subjected to indentation load. The peak force and energy absorption capability also effected by indenter size which due to the contact area of indentation. As for the location of indentation, vertical edge gives highest peak force and energy absorption by the fact that vertical edge is the intersection of three walls of honeycomb cell.

Barely visible impact damage in scaled composite laminates: Experiments and numerical simulations

This paper investigates the effect of size and complexity of composite structures on the formation of low-velocity impact damage via experimental tests and numerical modelling. The ASTM standard low-velocity impact test and a scaled-up version of the test were conducted. A novel numerical technique is presented that combines 3D solid and thin 2D shell elements for modelling different domains to achieve a high level of fidelity locally under the impact location, whilst achieving good computational efficiency for large structures. Together with the experimental studies at the different scales, the predictive capability of the numerical models was systematically validated. This modelling method demonstrated an advanced computational efficiency without compromising predictive accuracy. The models are applied to a case study of low-velocity impact of a large-scale stringer-stiffened panel, showing this modelling approach to be suitable for predicating low-velocity impact damage and structural response of laminated composites over a range of sizes and complexities.