Papers by Keyword: Low-Velocity Impact

Abstract: The study investigates LVI testing on woven carbon fiber-reinforced composite laminates at three different energy levels and assesses the specimens for their compressive strengths. X-ray CT scans are used to study the damaged envelopes, which allows better insights into the damage progression and failure mechanisms of the composite. The study investigates how post-impact damage propagation is influenced by alterations in impact energy and stacking orientation. The findings demonstrated that several variables, such as the characteristics of the constituent materials, the stacking order, laminate thickness, and ply orientations, had an impact on the CAI strength of the composite laminate. These findings highlight the importance of considering multiple factors when designing composite materials that can withstand impact loading and maintain their structural integrity. Even in specimens showing barely perceptible surface damage, a considerable drop in compressive strength is seen after the LVI testing. When specimens are struck with 25 J of energy, the compressive strength reduction reached a maximum value of 15.68%. In CAI testing, it is typical for sub-laminates to buckle near the impact-induced damage zone, resulting in failure. The magnitude of impact damage area can significantly affect the CAI strength, as the damaged area may create a stress concentration that can lead to buckling or other types of failure. Therefore, it is important to consider the impact energy and damage size when evaluating the CAI strength of composite materials.

Abstract: This paper presents the performance of the three-dimensional progressive damage model using Puck failure criteria gradual degradation law to predict the structural responses, as well as the onset and propagation of failure due to different meshing techniques. The proposed damage model is performed using Abaqus explicit analysis. Three meshing strategies are analyzed using a solid element finite element model based on low-velocity impact loading. The structural responses are compared with experimental data taken from literature to measure the performance of such damage model. The results revealed that the models adopted here respond well to experimental data and demonstrate acceptable results in predicting the inter- and intra-laminar damage of the composite laminate.

Abstract: Deformation and fracture analysis of the composite elements and structures under high-velocity impact is still associated with many problems. These problems are related not only to the complexity of taking into account the composite layered orthotropic structure and various failure scenarios but also to the problems of instrumented high-velocity impact tests to verify the calculation results. Different requirements for accuracy and numerical efficiency are imposed on the models and their predictive ability depending on the design stage. At the initial design stages, the model should allow one to estimate the energy absorption of the composite structure adequately. At later stages, the size of the damaged area and the fracture pattern also should be predicted with high accuracy. This article describes a simplified approach to the verification of deformation and fracture models of structural composites under high-velocity impact based on low-velocity impact test data. The model with the found parameters makes it possible to predict with satisfactory accuracy the energy absorption of the composite material.

Abstract: Recently, the growing attraction to the development of new eco-sustainable composite materials is driving the research interest toward the replacement of synthetic reinforcing fibres with natural ones and exploiting the inherent recyclability of thermoplastic resins even for uses in which thermosetting matrices are well consolidated (e.g. naval and aeronautical fields). Among the natural fibres, a growing interest of the research is addressed to basalt fibres. Focusing the attention on thermoplastic composites, many experimental findings already available in literature highlight the outstanding mechanical properties of composite materials including basalt fibres and their potentiality concerning glass ones. On the other hand, some issues are related to the surface properties of the bio-laminates: in particular, the wear ones, the flame resistance and the aesthetic appearance have to be improved to extend the application fields of these materials. Aiming to these goals, this paper deals with the study of the deposition ofaluminium coating through cold spray process on polypropylene/basalt fabric composite laminates. The specimens were obtained by film stacking, and compression moulding technology and their performances were studied in terms of low-velocity impact behaviour, considering the influence of the surface modification with the aluminium coating. The results obtained from the reference laminates and the coated ones are compared in terms of impact parameters: the aluminium deposition seems to affect the damage mechanism propagation even if the impact response seems to be similar in both conditions.

Abstract: This paper investigates the damage behavior of thermoset and thermoplastic fiber-reinforced composites. The specimens were subjected to low-velocity impacts (LVI) to produce barely visible impact damages (BVID). To compare the dependency of the matrix system and the laminate lay-up on the impact damage, four test series were set up. Therefore, laminates with an epoxy (EP) and a polyether ether ketone (PEEK) matrix in a quasi-isotropic (QI) [+45/0/-45/90]_2s and an orthotropic (OT) fiber lay-up [0/90]_4s were manufactured. To eliminate the influence of variant fiber systems, the thermoplastic tape and the thermoset prepreg contain similar carbon fibers (CF). After impact testing with three different impact energies, inner damages were investigated by using ultrasonic analyses. To get a deeper understanding of the interior damage mechanisms, cross sections of the damaged areas were examined via reflected light microscopy. By using these destructive and non-destructive test methods, significant differences in the damage behavior of composites with thermoplastic and thermoset matrix systems were identified for both laminate lay-ups.

Abstract: Numerical simulation is performed to study the deformation and failure modes of Al 1100 plate of 2.4 mm thickness, subjected to low-velocity impact. Blunt and hemispherical nose shaped impactors are used in this study. The quasi-static tensile test is performed at a strain rate of 0.01/s to obtain the Johnson-Cook material parameters which are used in numerical simulation software, ABAQUS/CAE to perform impact analysis. Mesh convergence study is carried out to decide the appropriate number of elements for numerical analysis. The impact behavior of Al 1100 plate for each impactor shapes are studied at 22 J impact energy. Result indicate that increased in the nose radius of impactor will increase the amount of deformation energy for aluminium plate.

Abstract: Several investigations regarding the mechanical behaviour of composites reinforced by natural fibers under impact have been realized recently, aiming at achieve a low-weight and resistant design. At the same time, progressively accurate results on numerical simulations have been reached powered by modern Finite Element Method (FEM) approaches for composites; however, demonstrating a faithful indentation pattern is still a challenge. The present work aims at building an impact numerical simulation that exhibits a fracture mechanism exactly like the one seen in experimental tests, also carried in this work, on a Basalt Reinforced Composite Polymer (BRFP) plate subjected to low-velocity falling weight impact (IFW). The FEM simulation describes a multiphase model considering each ply and their inter-layer interactions.

Abstract: The use of sandwich structures is well established in industrial sectors where high stiffness and strength combined with lightweight are required, like in marine, wind turbine and railway applications. However, the vulnerability of sandwich structures to low-velocity impacts limits its use in primary aircraft structures. Pin reinforcement of the foam core enhances the out-of-plane properties and the damage tolerance of the foam core. In this paper, a finite element model is proposed to predict the impact behaviour of pin-reinforced sandwich structure. An approach based on the building block approach was used to develop the model. Multi-scale modelling in the impact region that considers the delamination of the face sheet using cohesive zone elements was employed to increase the accuracy of the simulation. Impact tests were performed to validate the numerical model. A good agreement between numerical and experimental results in terms of contact-force displacement history and failure mode was found.

Abstract: In this study, an attempt has made to explore the low-velocity impact response of a Carbon/epoxy laminate (CFRP) and E-Glass/epoxy laminates (GFRP). The composite was reinforced with Graphene Nanoplatelets (GnPs) and impact energy absorption capacity was studied. The plain GFRP and plain CFRP were served as a baseline for comparison. These composite laminate plates were fabricated using hand layup technique. The tests were carried out on the laminate plate as per ASTM D5628 FD. Impact tests were performed using a specially designed vertical drop-weight testing machine with an impactor mass of 1.926 kg. The result shows that laminate plate reinforced with GnPs reinforcement enhances the impact energy absorption capacity of the composites almost 4.5 % in the case Carbon/epoxy laminate and 3.5 % in the case of and E-glass/epoxy laminate. The enhanced impact resistance could be attributed to increased interlaminar fracture toughness of the fibres.

Abstract: This paper presents an experimental investigation of mechanical and impact properties of carbon and Kevlar-glass composites prepared from pre-impregnated materials. Namely, flexural performance in three-point bending at different temperatures is evaluated. Moreover, Charpy impact test and low-velocity impact test are also conducted for classification of impact properties and character of rupture. These all properties are important for material design of sport bike rims and many sport and other applications.