Numerical simulation of the dynamic response in pulse-loaded fibre-metal-laminated plates

This article presents a three-dimensional constitutive model to replicate the dynamic response of blastloaded fibre–metal laminates made of 2024-0 aluminium alloy and woven composite (glass fibre–reinforced polypropylene). Simulation of the dynamic response is challenging when extreme localised loads are of concern and requires reliable material constitutive models as well as accurate modelling techniques. It is well known that back layers in a fibre–metal laminate provide structural support for front layers; thus, proper modelling of constituent failure and degradation is essential to understanding structural damage and failure. The improved developed model to analyse damage initiation, progression and failure of the composite is implemented in finite element code ABAQUS, and a good correlation is observed with experimental results for displacements of the back and front faces as presented by other researchers. The model was also able to predict accurately the tearing impulses. Finally, the concepts of the ‘efficiency of the charge’ and ‘effectiveness of the target’ are proposed in the context of localised blast loading on a structure. Dimensionless parameters are introduced to quantify these parameters

Application of the penalty coupling method for the analysis of blood vessels

Due to the significant health and economic impact of blood vessel diseases on modern society, its analysis is becoming of increasing importance for the medical sciences. The complexity of the vascular system, its dynamics and material characteristics all make it an ideal candidate for analysis through fluid structure interaction (FSI) simulations. FSI is a relatively new approach in numerical analysis and enables the multi-physical analysis of problems, yielding a higher accuracy of results than could be possible when using a single physics code to analyse the same category of problems. This paper introduces the concepts behind the Arbitrary Lagrangian Eulerian (ALE) formulation using the penalty coupling method. It moves on to present a validation case and compares it to available simulation results from the literature using a different FSI method. Results were found to correspond well to the comparison case as well as basic theory

A review of composite structures subjected to dynamic loading

The following review of composite impact work summarises key research interests and provides a brief overview for the development of theoretical, experimental and numerical methods for low, high, and hyper velocity impact. Particular attention is given to experimental apparatus and techniques used for the different impact velocity regimes, and the implementation of failure criteria in finite element (FE) modelling methods which predict material behaviour. Areas are then identified for which limited research has been currently undertaken and suggestions are made for possible future research topics

"A case of self-induced reflex epilepsy "

The term reflex epilepsy in reserved for a small subgroup o seizures that occur regularly in response to specific stimuli. Our patient is a 20- year old male, who had pleasure, euphoria, loss of conciousness and generalized tonic- clonic convulstion when he watched TV since ten years. During puberty the patient that self-induced reflex epilepsy with photic stimulation, when watching TV or looking at sun and with had moving in front of his eyes to produce flickers. The patient first had sex pleasure, euphoria, erection and ejaculation, and then developed loss of consiousness and generalized tonic- clonic seizure, that took about 4-5 min. what is more intersing is that he asked us for a kind of drug that controlled his generalized tonic-clonic seizures but not his pleasure and orgasm, and he said that he would refuse any drug interfered with his orgasm

The Relationship between Religious Tendency and Successful Aging

Successful Aging is a suitable pattern of aging that has been paid due attention in recent years. Due to the growth rate increase of elders’ population in the world, and higher life expectancy in different countries, the quality of life is of interest to everyone. Thus the recognition of the basic factors of successful aging is of prime importance. Accordingly, this study has investigated one of the variables which are the religious tendency and its relationship with successful aging. Based on the available operational definitions of successful aging, Life Satisfaction Scale (L.S.S.) and General Health Questionnaire (GHQ-12) were used as the research instruments. Religious tendency was assessed by Religious Orientation (R.O.). The data were analyzed by t test, F test and Logistic Regression. The results showed significant relationship between religious orientation and successful aging

On dimensionless loading parameters for close-in blasts

Close-range blasts pose a threat through severe damage to structures and injury or death. In this work, the spatial and temporal descriptions of a localised blast load are presented using 6 non-dimensional parameters. These are found to be solely functions of the charge stand-off distance to diameter ratio for a cylindrically-shaped charge. Numerical simulations of a localised blast are performed using AUTODYN, where the pressure variation on a rigid barrier for various charge stand-off/diameter combinations is obtained. The least-square regression is then utilised to obtain the relationship between stand-off/diameter ratio and dimensionless loading parameters. The relevant expressions and dimensionless charts are presented. The proposed equations are verified by comparing experimental data with numerical results obtained by finite element analysis (FEA) of blast loaded steel plates (using the user-defined subroutine VDLOAD implemented in the FEA package ABAQUS/Explicit). Excellent correlation of the measured permanent displacement with numerically predicted results is obtained

Numerical and experimental investigations of water hammers in nuclear industry

In nuclear and petroleum industries, supply pipes are often exposed to high pressure loading which can cause to the structure high strains, plasticity and even, in the worst scenario, failure. Fast Hydraulic Transient phenomena such as Water Hammers (WHs) are of this type. It generates a pressure wave that propagates in the pipe causing high stress. Such phenomena are of the order of few msecs and numerical simulation can offer a better understanding and an accurate evaluation of the dynamic complex phenomenon including fluid-structure interaction, multi-phase flow, cavitation … For the last decades, the modeling of phase change taking into account the cavitation effects has been at the centre of many industrial applications (chemical engineering, mechanical engineering, …) and has a direct impact on the industry as it might cause damages to the installation (pumps, propellers, control valves, …). In this paper, numerical simulation using FSI algorithm and One-Fluid Cavitation models ("Cut-Off" and "HEM (Homogeneous Equilibrium Model) Phase-Change" introduced by Saurel et al. [1]) of WHs including cavitation effects is presented

Dynamic plastic response of beams subjected to localised pulse loads

Localised blast loads give rise to high gradients of overpressure detrimental to structural elements as beams and plates. This article presents an analytical study on the dynamic plastic response of beams made of a ductile metallic material due to close-in pulse pressure loading. The close-in pressure load is characterised by a spatially varying function constant over a central region and exponentially decaying beyond it. The temporal pulse shape is assumed to take different forms. The exact static plastic collapse load was obtained for the characteristic load using the framework of plastic limit analysis, whereby the analysis was then extended to the dynamic case by considering the appropriate yield surface and inclusion of inertia forces. The yield surfaces considered were representative of pure bending, the interactions between the bending moment and transverse shear, and bending moment and membrane force, each corresponding to a special case depending on the geometry of the beam. A time-dependent, kinematically admissible velocity profile was assumed to treat the dynamic formulations in interaction of each phenomenon. A study on the strain-rate sensitivity was also presented, and existence of a critical pressure triggering the apparition of travelling plastic hinges was hence highlighted. For blast loads of high magnitude, the expressions for normalised deflection were furnished in terms of the impulsive velocity. The analytical models were validated by performing a parametric study on the two-dimensional representative of the beam model in commercial finite element software ABAQUS 6.14. The numerical results show a good correlation with the analytical results in each case