Modeling Large Deformation and Failure of Expanded Polystyrene Crushable Foam Using LS-DYNA

In the initial phase of the research work, quasistatic compression tests were conducted on the expanded polystyrene (EPS) crushable foam for material characterisation at low strain rates (8.3×10-3~8.3×10-2 s−1) to obtain the stress strain curves. The resulting stress strain curves are compared well with the ones found in the literature. Numerical analysis of compression tests was carried out to validate them against experimental results. Additionally gravity-driven drop tests were carried out using a long rod projectile with semispherical end that penetrated into the EPS foam block. Long rod projectile drop tests were simulated in LS-DYNA by using suggested parameter enhancements that were able to compute the material damage and failure response precisely. The material parameters adjustment for successful modelling has been reported

A comparison of energy absorbing capabilities of paper and steel structures subjected to progressive failure under free falling objects

An inverted paper cup of 0.26 mm thickness was subjected to deformation under a freely falling steel ball at a velocity of 2.77 m/sec. The deformed features of the paper cup were measured. The dynamic loading event was simulated using piecewise linear plasticity material model in LSDYNA. Deformed shape of the paper cup in finite element model matched closely with experimental results with ignorable small discrepancies. The paper cup was able to absorb all the kinetic energy of the falling steel ball for the above mentioned falling speed and the ball did not bounce out of the cavity generated by the impact. In LSDYNA a similar size steel cup was also subjected to a freely falling ball with same speed and the energy absorbed was compared to the energy absorbed by the paper cup. It was found that under similar conditions a paper cup would undergo a significant progressive failure and absorb all the energy of the falling object

NARRATIVE CONSTRUCTION AND ITS SOCIAL VITALITY

Resilient narrative construction confines to the prevalence and function of Ideolog-based conflicts. While robust coordination and substantial enforcement strategies enhance the social vitality of narrative to bring about the desired social change. This article seeks to explore the narrative construction and its social vitality in the context of conflict and societal development. New narrative theoretical discoursereveals that deliberate narrative construction concentrates on individuals and society to redirect them in accordance with the wishes of narrative mentors. The conflict engendering elements like containment, self-identification of the individuals, and social positioning are, thus, subordinated to the narrative. This paper while using the narratological framework is looking at the phenomenon of socio-anthropological change from the perspective of narratology. The study could be of importance to students of low-intensity conflicts and militancy, especially corresponding to terrorism. The paper concludes that this new outlook of narrative has enlarged its scope beyond the corridors of literature into the renewed field of social narratology with an immense bearing on human behavior and attitudes.   Bibliography Entry Shah, Qasim Ali, Bahadar Nawab, and Arifullah Khan. 2020. "Narrative Construction and Its Social Vitality." Margalla Papers 24 (1): 147-157

Multi-particle reconstruction with dynamic graph neural networks

The task of finding the incident particles from the sensor deposits they leave on particle detectors is called event or particle reconstruction. The sensor deposits can be represented generically as a point cloud, with each point corresponding to three spatial dimensions of the sensor location, the energy deposit, and occasionally, also the time of the deposit. As particle detectors become increasingly more complex, ever-more sophisticated methods are needed to perform particle reconstruction. An example is the ongoing High Luminosity (HL) upgrade of the Large Hadron Collider (HL-LHC). The HLHLC is the most significant milestone in experimental particle physics and aims to deliver an order of magnitude more data rate compared to the current LHC. As part of the upgrade, the endcap calorimeters of the Compact Muon Solenoid (CMS) experiment – one of the two largest and generalpurpose detectors at the LHC – will be replaced by the radiation-hard High Granularity Calorimeter (HGCAL). The HGCAL will contain ∼ 6 million sensors to achieve the spatial resolution required for reconstructing individual particles in HL-LHC conditions. It has an irregular geometry due to its hexagonal sensors, with sizes varying across the longitudinal and transverse axes. Further, it generates sparse data as less than 10% of the sensors register positive energy. Reconstruction in this environment, where highly irregular patterns of hits are left by the particles, is an unprecedentedly intractable and compute-intensive pattern recognition problem. This motivates the use of parallelisationfriendly deep learning approaches. More traditional deep learning methods, however, are not feasible for the HGCAL because a regular grid-like structure is assumed in those approaches. In this thesis, a reconstruction algorithm based on a dynamic graph neural network called GravNet is presented. The network is paired with a segmentation technique, Object Condensation, to first perform point-cloud segmentation on the detector hits. The property-prediction capability of the Object Condensation approach is then used for energy regression of the reconstructed particles. A range of experiments are conducted to show that this method works well in conditions expected in the HGCAL i.e., with 200 simultaneous proton-proton collisions. Parallel algorithms based on Nvidia CUDA are also presented to address the computational challenges of the graph neural network discussed in this thesis. With the optimisations, reconstruction can be performed by this method in approximately 2 seconds which is suitable considering the computational constraints at the LHC. The presented method is the first-ever example of deep learning based end-to-end calorimetric reconstruction in high occupancy environments. This sets the stage for the next era of particle reconstruction, which is expected to be end-to-end. While this thesis is focused on the HGCAL, the method discussed is general and can be extended not only to other calorimeters but also to other tasks such as track reconstruction

Numerical analysis on materials energy absorbing capability under gravity loading impact

Energy absorbers are systems that convert kinetic energy into other forms of energy, such as pressure energy in compressible fluids, elastic strain energy in solids, and plastic defonnation energy in defom1able solids. The process of conversion for plastic defonnation depends, among other factors, on the magnitude and method of application of loads, transmission rates, defonnation displacement pattems, and material properties. The applications of defonnable energy absorbers have been paid serious attention for several decades, for the means of safety. The aim is to minimize the impact by controlling the deceleration pulse during impact, i.e. extending the period of dissipation of kinetic energy. Cushioning devices on vehicle bumpers, crash retarders in emergency systems of lifts, and some crash barriers used as road blocks are everyday examples. The vital application of this work is reliability of energy to absorb massive landing force, for instance the missile safeguards when landing on the ground. The high energy absorbing ability can practically applied into rocket system for sending the chips or any other important materials to the space or far-distant place, thus protecting the chips from damag

Simulation setup of pipe whip impact

The safety of pipe whip is related issue for nuclear power and chemical plants, where pIpes are often used to transport fluids at high pressure and high temperature. Simulation analysis for empty pipe and liquid filled pipe are conducted in this study. The model was made of simple pipe whip system which enables the missile pipe to hit the target pipe at an angle of 90° and also 55° oblique impact. The simulation setup is done by LS-DYNA which is an developed by the Livennore Software Technology Corporation (LSTC). It is a highly nonlinear transient dynamic finite element analysis using explicit time integratio

Experimental setup of pipe whip impact

Pipe whip is a safety related issue for nuclear power and chemical plants, where pipes are often used to transport fluids at high pressure and high temperature. Experiment works for empty pipe and liquid filled pipe are needed in this study. The model was made of simple pipe whip system which enables the missile pipe to hit the target pipe at an angle of 90° and also 55° oblique impact. The possible damages occur on the target pipe when the missile pipe hit it at certain velocity depend on the different mass of dropper and different diameter ofthe target pipe. Copper pipe is used as the target pipe and steel as the missile pip

Simulation results of pipe whip impact at 55° angle

The safety of pipe whip is related issue for nuclear power and chemical plants, where pIpes are often used to transport fluids at high pressure and high temperature. Simulation analysis for empty pipe and liquid filled pipe are conducted in this study. The model was made of simple pipe whip system which enables the missile pipe to hit the target pipe at an angle of 55° oblique impact. The simulation setup is done by LS-DYNA which is highly nonlinear transient dynamic finite element analysis using explicit time integration. The results show the defonnation occurred in the pipe whip at different degrees of impact

Experimental results of liquid slosh in a cylindrical tank with different fill levels

The fundamental properties of slosh could be effectively investigated through laboratory experiments under controlled conditions. Such experiments can provide considerable insight into the fluid slosh and associated forces and moments. The nlajority of the experimental investigations on the fluid slosh have been conducted in model tanks which are small in size compared to the full scale tanks of cross-section area in the order of 3.5 mn2. The cross-sectional areas of the model tanks employed in the reported studies were in the order of 0.2 m' [I-31. Since the similarity of sloshing fluid flows is very complex, the slosh behavior would be expected to differ for different tank sizes. Moreover, some of the reported slosh studies were limited to measurements of hydrodynamic pressure at given points or only one component of the slosh forces. The stability of a road tank vehicle, however, is strongly dependent on the resultant slosh forces and moments arising in all the translational and rotational axe