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Granular material exhibits rich dynamical behaviors under impacting, and its impacting dynamical process is seriously influenced by many factors. The purpose of this paper is to explore the dynamical response of granular bed obliquely impacted by a rotational projectile, and the effect of density ratio and diameter ratio on its penetration depth is mainly considered.

In most experiments, as the angular velocity and the impact velocity always produce a coupling effect on the whole impact process, then it is quite difficult to separately distinguish the influence of angular velocity. Therefore, the discrete element method is used here to achieve this purpose. The authors vary one parameter and keep other parameter unchanged, and then discuss the effect of these parameters on penetration depth statistically.

The numerical model in this paper can effectively predict the dynamical process of granular medium under impacting. The projectile’s penetration depth exhibits a similar scaling with its angular velocity under different density ratios and diameter ratios, and the angular velocity exhibits an obvious criticality.

A DEM code and corresponding statistical approach are used to explore the complex dynamical process of a granular material obliquely impacted by a rotation projectile.

The purpose of this study is to design and develop new spiral head projectiles undergoing ballistics impact.

The introduction of the rifled barrel in firearms made projectile spin during its flight path. The central translational velocity (impact velocity) is one parameter to defeat/penetrate the target in the penetration process. Another important parameter considered to be the shape of the projectile. Many types of projectile shapes have been designed to defeat the target. In the recent years, ogival nose shape is one of the well-known projectile shapes in use abundantly. The present research is made to design the nose shape so as to use the spin during the penetration of target effectively. In this study, a new spiral head projectile shape is proposed and designed, which uses the rotation of projectile (spin) for penetrating the Al7075-T6 target. When the ogive and new spiral head projectile is impacted on Al 7075-T6 target of 12.5 mm, 18 mm thicknesses at ordnance velocities, the residual velocity is evaluated numerically using ANSYS/Explicit Dynamics at normal impact condition. Two projectile materials, steel 4340 and tungsten alloy, are used as projectile materials. Along with the translational velocity, rotation velocities (spin rate) 13,000, 26,000 and 52,000 rad/s also provided to projectile. The residual velocities verses spin rate are plotted for different spiral angle projectiles for impact velocities 1,000–1,500 m/s, at normal impact conditions on the Al 7075-T6 target. Compared with the ogive nose projectile, the proposed new spiral head projectile made of tungsten alloy is significantly effective.

Spiral head projectile having tungsten alloy material gives encouraging results at 12.5 mm target thickness. The new spiral head projectile is damaged partially. At 18 mm target thickness impact conditions, it is observed that the projectile head is completely damaged. The effectiveness of spiral head projectile on a target plate thickness of 18 mm is considered to study the impact condition.

All the above results need to be experimentally verified. However, the basic numerical model used in the present study, i.e. the basic ogive nose numerical model with only translational energy, is well validated with penetration theory available in literatures.

The designed new spiral head projectile is only effective with tungsten alloy material within considered design parameters. For steel 4340 material, the spiral head projectile is less effective than the ogive nose projectile. In tungsten alloy projectiles, by observing all considered spiral angles, 30-degree spiral angle projectile gives the best performance at most of the considered impact velocity conditions.

The proposed research outputs are original, innovative and, have lot of importance in defence applications particularly in arms and ammunitions.

Metal plates are usually used as protective shields of engineering structures, which probably undergo multiple projectile impacts resulting from gunshot and blast. Though a large number of studies have been conducted on the performance of metal plates under a single projectile impact, few studies have explored their performance under multiple projectile impacts. This paper aims to explore the performance of Weldox 460 E steel plates against multiple projectile impacts through numerical simulation.

A three-dimensional coupled finite element (FE) and smoothed particle hydrodynamics (SPH) model was developed to simulate the perforation of a 12-mm-thick Weldox 460 E steel plate by an ogival projectile. The model was verified by existing experimental data. Then, it was extended to investigate the same target plate subjected to impacts with multiple projectiles. Simultaneous impacts with different number of projectiles, as well as sequential impacts with two projectiles, were considered.

Effects of spacing between projectiles on residual velocity of projectile, ballistic limit and failure mode of target were revealed for simultaneous impacts. Effects of spacing and axial distance between projectiles on residual velocity of projectile were explored for sequential impacts.

This work developed an advanced FE–SPH model to simulate perforation of steel plates by multiple projectiles, and revealed the effects of multiple impacts on ballistic performance of steel plates. It provides guidance for the design of protective structures/shields in various engineering applications.

The purpose of this paper is to suggest that the effects of service quality (SQ) on outcome variables may shift over time. However, scant attention has been paid to capturing that shift. The current study uses the theory of relationship dynamics to capture the rate and direction of change in the effects of SQ attributes on customer satisfaction (CS) and emotional attachment (EA). For this purpose, the study takes CS-velocity and EA-velocity as dynamic outcomes of SQ.

A sample of 306 restaurant consumers responded to a structured questionnaire at three points in time. Confirmatory factor analysis was carried out, followed by analysis of the data through latent growth curve modeling using MPlus (Version 8.1).

SQ attributes positively affect CS and EA, but these effects diminish over time, as SQ attributes negatively influence CS-velocity and EA-velocity. In addition, the study demonstrates that dynamic elements strongly impact behavioral intentions (BI).

The study enables service and relationship marketing managers to better understand the role of SQ attributes in maintaining longitudinal satisfaction, attachment and BI. The insights from this longitudinal investigation help managers to formulate long-term service management and relationship management strategies.

This study is the first attempt to examine SQ’s dynamic outcomes using longitudinal panel data. It is the first study to introduce EA-velocity as a dynamic construct of EA and the first to examine the relationships of CS-velocity and EA-velocity with BI.

The purpose of this paper is to describe a procedure to simulate impact-driven liquid jets by computational fluid dynamics (CFD). The proposed CFD model is used to investigate nozzle flow behavior under ultra-high injection pressure and jet velocities generated by the impact driven method (IDM).

A CFD technique was employed to simulate the jet generation process. The injection process was simulated by using a two-phase flow mixture model, while the projectile motion was modeled the moving mesh technique. CFD results were compared with experimental results from jets generated by the IDM.

The paper provides a procedure to simulate impact-driven liquid jets by CFD. The validation shows reasonable agreement to previous experimental results. The pressure fluctuations inside the nozzle cavity strongly affect the liquid jet formation. The average jet velocity and the injection pressure depends mainly on the impact momentum and the volume of liquid in the nozzle, while the nozzle flow behavior (pressure fluctuation) depends mainly on the liquid volume and the impact velocity.

Results may slightly deviate from the actual phenomena due to two assumptions which are the liquid compressibility depends only on the rate of change of pressure respected to the liquid volume and the super cavitation process in the generation process is not taken into account.

Results from this study will be useful for further designs of the nozzle and impact conditions for applications of jet cutting, jet penetration, needle free injection, or any related areas.

This study presents the first success of employing a commercial code with additional user defined function to calculate the complex phenomena in the nozzle flow and jet injection generated by the IDM.

The purpose of this paper is to analyse the dynamic behaviour of an elasto‐plastic sandwich subjected to low velocity impact.

A numerical model is developed with the assumption that the plastic deformation is confined under the contact area. The structure is analyzed using the in‐house finite element code with an appropriate contact law. During the impact progression, two phases (elastic and plastic) related to the impact intensity are considered in the dynamic model. The proportional viscous damping is incorporated in the model. An elasto‐plastic impact algorithm is established to determine the impact force, the sandwich structure displacement and indentation.

The numerical results are validated by experimental dropping weight impact tests. The influences of the impactor radius, the core material variation and the impactor initial velocity on the dynamic behaviour of the impacted structure are studied.

In order to study the low velocity impact problems by considering the caused plastic deformations, a simple numerical elasto‐plastic impact model of sandwich structure is proposed.

The purpose of this paper is to present and analyze the iterative rules determining the impulsive behavior of a rigid disk having a single or possibly multiple frictionless impact with two walls forming a corner.

In the first part, two theoretical iterative rules are presented for the cases of ideal impact and Newtonian frictionless impact with global dissipation index. In the second part, a numerical version of both the theoretical algorithms is presented.

The termination analysis of the algorithms differentiates the two cases: in the ideal case, it is shown that the algorithm always terminates and the disk exits from the corner after a finite number of steps independently of the initial impact velocity of the disk and the angle formed by the walls; in the non-idealcase, although is not proved that the disk exits from the corner in a finite number of steps, it is shown that its velocity decreases to zero, so that the termination of the algorithm can be fixed through an “almost at rest” condition. It is shown that the stable version of the algorithm is more robust than the theoretical ones with respect to noisy initial data and floating point arithmetic computation. The outputs of the stable and theoretical versions of the algorithms are compared, showing that they are similar, even if not coincident, outputs. Moreover, the outputs of the stable version of the algorithm in some meaningful cases are graphically presented and discussed.

The paper clarifies the applicability of theoretical methods presented in Pasquero (2018) by analyzing the paradigmatic case of the disk in the corner.

Dynamic response of open-cell metal foam under low-velocity impact loading is important in applications involving impact resistance and energy absorption, etc. Assuming that metal foam is a conceptually continuous material, the macroscopic mechanical behaviors, both static and dynamic, must be studied. Within the dynamic mechanical properties of metal foam, impact response becomes the renewed interest to understand the characteristics of impact deformation. The present work aims to experimentally and numerically analyze the low-velocity impact response of open-cell metal foam. A series of low-velocity drop impact tests are realized on the open-cell metal foam samples with different relative densities and at different impact velocity. Afterwards, a well compiled program in Python controls the whole multiple drop impact process on each sample of metal foam. Corresponding numerical modeling and the simulation for single impact analysis are continuously carried out with the finite element (FE) program ABAQUS/Explicit. Proper meshing technique, loading and boundary conditions are conducted on all the foam models, and at the same time, the required mechanical properties: elastic module, Poisson's ratio, uniaxial stress-strain response and strain-rate dependence are utilized. In conclusion, the simulated results provide the good agreements with the experimental results in the case of low-velocity impact testing of open-cell metal foam. Experimental procedure and numerical simulation offer good approaches to improve the impact resistance and energy absorption of the open-cell metal foam.

The present study deals with the numerical modeling of the low-velocity impact damage of laminated composites which have increasingly important applications in aerospace primary structures. Such damage, generated by various sources during ground handling, substantially reduces the mechanical residual performance and the safe-service life. The purpose of this paper is to present and validate a computationally efficient approach in order to explore the effect of critical parameters on the impact damage characteristics.

Numerical modeling is considered as one of the most efficient tool as compared to the expensive and time-consuming experimental testing. In this paper, a finite element model based on explicit dynamics formulations is adopted. Hashin criterion is applied to predict the intralaminar damage initiation and evolution. The numerical analysis is performed using the ABAQUS® programme.

The employed modeling approach is validated using corresponding numerical data found in the literature and the presented results show a reasonable correlation to the available literature data. It is demonstrated that the current model can be used to capture the force-time response as well as damage parameter maps showing the intralaminar damage evolution for different impact cases with respect to the physical boundary conditions and a range of impact energies.

Low-velocity impact damage of laminated composites is still not well understood due to the complexity and non-linearity of the damage zone. The presented model is used to predict the force-time response which is considered as one of the most important parameters influencing the structural integrity. Furthermore, it is used for capturing the damage shape evolution, exhibiting a high degree of capability as a damage assessment computational tool.

Fragment impact is one of the main threats for the safety of storage tank in aircraft. This study aims to investigate the influence of inserted baffle on hydrodynamic ram (HRAM) and damage of storage tank to optimize the protective performance of storage tank under fragment impact.

The characteristics of initial shock wave, cavity evolution, velocity attenuation of fragment and anti-penetration performance of baffle-inserted tanks were evaluated by experimental and numerical methods.

Results indicated that the inserted baffle in tank could significantly increase the velocity attenuation rate of fragment in water. The volume of the second cavity caused by the inserted baffle rapidly decreased with the baffle position moving backward. For the baffle-inserted tank, the deformation of the front and rear walls was substantially weakened, and the alleviating effect for front wall was more significant. Comparing with the ordinary storage tank, the inserted baffle at normalized position 0.25, 0.5 and 0.75 in tank made the ballistic limit velocity of storage tank increasing by 118.3%, 20.0% and 54.0%, respectively.

The findings of this work illustrating the HRAM history and damage map of storage tanks after inserted baffle could provide a convenient approach to improve the anti-penetration performance of storage tanks effectively.