In this paper, a finite element model is presented for the transient analysis of Low velocity impact, and the impact induced damage in the composite plate subjected to Low velocity impact is studied. The failure criteria suggested by Choi and Chang and the Tsai-Hill failure criteria are used for the prediction of the damage in the composite plate; then the effect of various parameters on the impact induced damage is investigated. The first order shear deformation plate theory and the Ritz finite element method are employed for modeling the behavior of plate, and the modified Hertz contact Low is used for the prediction of the contact force through the impact. In the numerical results, the time history of indentation, contact force and stress during the impact and the impact induced damage is investigated. The matrix cracking and delamination in the plies of the laminated composite plate subjected to Low velocity impact are studied and the effects of various parameters are investigated.

The structures realized using sandwich technologies combine Low weight with high energy absorbing capacity, so they are suitable for applications in the transport industry (automotive, aerospace, ship building industry) where the “ lightweight design” philosophy and the safety of vehicles are very important aspects. While sandwich structures with polymeric foams have been applied for many years, currently there is a considerable and growing interest in the use of sandwiches with aluminum foam (AFS) core. The aim of this paper was the analysis of Low-velocity impact response of aluminum foam sandwich panels in two different types (integral skins and bonded skins) and the investigation of their collapse modes using computed tomography (CT). A theoretical approach, based on the energy balance model, has been applied to investigate their impact behavior and the model parameters were obtained directly from the measurements carried out on CT images of the impacted sandwiches. The AFS structures are relatively intact compared to the more catastrophic and localized fracture of the polymeric sandwiches, so the mechanical properties and their performance after imact will be better than polymeric sandwiches.

This paper describes a strategy for predicting the extent of internal damage in a laminated composite structure, when subjected to Low velocity impact. The success of the predictions is validated by experiments. Delamination as a result of Low-velocity impact loading is a major cause of failure in fiber-reinforced composites. The delamination size was obtained when the' transverse shear force rate reached interlaminar fracture toughness. Post-impact examination of damage is carried out by visual inspection. The impact loading is treated as an equivalent static loading by assuming the impactor to be semi-spherical and the contact to obey Hertzian law. An analytic solution which includes both transverse shear and contact deformation is presented. A First shear deformation theory is employed and solutions for the loads, displacements and strains are obtained using Fourier series expansions. Subsequently, the Tresca criterion is used to detect the zones of failure. It is demonstrated that for given specimens lay-up the materials subjected to impact load whit Low rang of energy suffer damage according to the magnitude of the both impactor mass and velocity.    

Based on numerical modelling, this study investigates asymmetric semicylindrical composite laminate shells' damage characteristics under Low-velocity impact loads. For this purpose, several asymmetric stacking sequences were subjected to Low-velocity impact and the results were analysed in terms of force, displacement, contact time, and absorbed energy. It is concluded that the maximum impact force decreases with an increase in the number of layers oriented at 0°, particularly in the upper half of the laminate. The laminates with a 45° orientation in the upper layers present the Lowest displacement values, whereas the laminates with the upper layers oriented at 0° exhibit longer contact times. It is also observed that intralaminar damage is responsible for almost half of the total impact energy, folLowed by delaminations and friction. Stacking sequences with upper layers at 45° exhibit slightly higher energy dissipation due to intralaminar damage (fibre failure) and interlaminar damage (delamination).

In this article, Finite Element Method (FEM) and Eulerian-Lagrangies Algorithm (ELA) formulation were used to numerically simulate the impact of several Low-velocity projectiles with water surface. Material models which were used to express behavior of air and water included Null material model. For the projectiles, rigid material model were applied. Results were validated by analyzing the impact of metallic cylinder with a water surface and then the impact of a wedge, sphere and special projectile at Low-velocities were simulated. Major outputs were force and pressure applied to the projectile, variations of velocity and acceleration when entering to the water, stress-strain variations and variations of water surface in various steps of the analysis. Results showed that the impact of the structure with fluid can be modeled using finite element model with high accuracy in terms of quality and quantity. Numerical results obtained for cylinder well agrees with the available experimental data. Also the results for other projectiles show a logical trend.

In the current study, Low velocity off-center impacts of glass/epoxy laminates considering different impact locations are investigated experimentally and numerically. Low velocity impact tests are performed using an instrumented drop-weight machine and the composite specimens are formed through the use of the vacuum infusion process. To simulate Low velocity impact properties of the composite, the finite element software ABAQUS/Explicit is employed. The damage model is implemented in the FE code by a user-defined material subroutine (VUMAT). In order to effectively describe the progressively intralaminar damage for composite laminates, two three-dimensional progressive damage models are presented exponentially and linearly and for predicting damage initiation of composite plates, 3D Hashin’s failure criterion is chosen.Both damage models are established as functions of energy dissipated by damage in addition to introducing the characteristic length for each three dimensional solid element. The contact force-time histories and peak loads are obtained to compare the numerical and the experimental results at several impact energy levels and three different impact locations of the composite plates. In addition to these achievements, the comparison of the numerically predicted damage pattern and damage size and those observed experimentally can verify the efficiency of the present models.

The bottom of floats and flying boat should be strong against impact loads such as Low velocity impact despite being light weight. In this article, we will investigate the dynamic behavior of the structure of meta-sandwich panels with different cores under Low velocity impact loading using analytical and numerical methods. Four different core samples including honeycomb, auxetic, square and triangular made of polylactic acid under impact, a hemispherical steel projectile with a radius of 15 mm with fixed boundary conditions have been investigated. The interaction between the impactor and the meta-sandwich panel has been modeled using a two-degree-of-freedom mass and spring system using finite element software such as ANSYS Workbench. The maximum impact contact force is also analytically and numerically compared with each other and the results show a good match between these two methods. Considering the importance of the effective parameters in the dynamic response of the sandwich panel structure, the effect of some parameters, including the velocity and mass of the impactor, on the maximum contact force, the maximum displacement and the maximum Von Mises stress were numerically investigated and evaluated. The results show that impactor velocity effects are a more important factor in increasing and decreasing contact force, displacement, Von Mises stress and impact time compared to impactor mass. In the end, by comparing the different cores presented in this article, the auxetic core is introduced as the best core among other cores.

In the present paper, a numerical study is performed to investigate the response of different plates aluminum alloys subjected to Low velocity impact condition. In this regard, the square AA5083-H116 aluminum plates with dimensions 300×300 and 3 mm and 5 mm thick under Low velocity impact are modelled, and a mesh convergence study is carried out to decide the appropriate number of elements. In this research, the influence of strain rate effects in Low velocity impact response is examined by doing a comparative study using the isotropic elasto-plasticity and the Johnson-cook material models. The response to impact events of models including deflection history and maximum and permanent deflection is extracted and validated by available numerical and experimental data in literature. The results indicate that the strain rate has a significant influence on time histories and increases the accuracy of the predicted data. Then, using the developed modeling procedure, the behavior of three aluminum alloys under Low velocity impact is investigated based on Johnson-Cook model. The results show that 7075-T6 and 6061-T6 alloys have the highest and Lowest stiffness, respectively. Also, the Lowest rate of absorbed energy to mass is observed in the 7075-T6 alloy.