scholarly journals Characterization of Impacts of Elastic-plastic Spheres

2020 ◽  
Vol 64 (2) ◽  
pp. 165-171
Author(s):  
Bence Szabó ◽  
Attila Kossa
Keyword(s):  
Plastic Material ◽  
Analytical Models ◽  
Material Models ◽  
Elastic Plastic ◽  
Analytical Functions ◽  
Elastic Plastic Material ◽  
Explicit Dynamic ◽  
The Impact ◽  
The Given

This work presents explicit dynamic finite element simulations of various impacts of elastic-plastic solid spheres with flat walls. Different  analytical models describing the mechanics of the impact phenomenon are also presented. Elastic and elastic-plastic material models for the sphere and the wall are considered during the analyses. The applicability of these different models is demonstrated and their accuracies are investigated. Closed-form analytical functions are proposed to describe the relationship between the initial velocity of the sphere and the investigated contact characteristics for the given material models. Analysis is carried out to study the effect of the friction coefficient as well as the angle of impact for various cases.

scholarly journals Numerical and Theoretical Analysis of the Inertia Effects and Interfacial Friction in SHPB Test Systems

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4809
Author(s):  
Pei Pei ◽  
Zhongcai Pei ◽  
Zhiyong Tang
Keyword(s):  
Theoretical Analysis ◽  
Elastic Material ◽  
Plastic Material ◽  
Inertia Effects ◽  
Elastic Plastic ◽  
Rate Dependent ◽  
Hardening Modulus ◽  
Structural Applications ◽  
Elastic Plastic Material ◽  
The Impact

The dynamic properties of materials should be analyzed for the material selection and safety design of robots used in the army and other protective structural applications. Split Hopkinson pressure bars (SHPB) is a widely used system for measuring the dynamic behavior of materials between 102 and 104 s−1 strain rates. In order to obtain accurate dynamic parameters of materials, the influences of friction and inertia should be considered in the SHPB tests. In this study, the effects of the friction conditions, specimen shape, and specimen configuration on the SHPB results are numerically investigated for rate-independent material, rate-dependent elastic-plastic material, and rate-dependent visco-elastic material. High-strength steel DP500 and polymethylmethacrylate are the representative materials for the latter two materials. The rate-independent material used the same elastic modulus and hardening modulus as the rate-dependent visco-elastic material but without strain rate effects for comparison. The impact velocities were 3 and 10 m/s. The results show that friction and inertia can produce a significant increase in the flow stress, and their effects are affected by impact velocities. Rate-dependent visco-elasticity material specimen is the most sensitive material to friction and inertia effects among these three materials (rate-independent material, rate-dependent elastic-plastic material, and rate-dependent visco-elastic material). A theoretical analysis based on the conservation of energy is conducted to quantitatively analyze the relationship between the stress measured in the specimen and friction as well as inertia effects. Furthermore, the methods to reduce the influence of friction and inertia effects on the experimental results are further analyzed.

Strain-Rate Effects in the Dynamic Buckling of a Simple Elastic-Plastic Model

1997 ◽  
Vol 64 (1) ◽  
pp. 193-200 ◽  
Author(s):  
D. Karagiozova ◽  
N. Jones
Keyword(s):  
Strain Rate ◽  
Plastic Material ◽  
Rate Sensitivity ◽  
Dynamic Buckling ◽  
Strain Rate Effects ◽  
Plastic Model ◽  
Elastic Plastic ◽  
Rate Effects ◽  
Elastic Plastic Material ◽  
The Impact

The phenomenon of dynamic buckling is examined when the influence of material strain-rate sensitivity is retained in the basic equations for a simple elastic-plastic model with linear strain hardening when subjected to an impact by a mass. Two approaches are proposed for taking into account the material strain-rate effects and both use the Cowper-Symonds constitutive equation. The critical impact velocities depend on the impact mass and are determined for a wholly elastic material, a strain-rate insensitive elastic-plastic material and an elastic-plastic material with a dynamic yield force together with linear or nonlinear hardening due to the strain-rate effects. The results obtained show that both strain-rate sensitive models predict impact velocities which are higher than those predicted by the strain-rate insensitive idealization and that the influence of any initial imperfections is important for the three material models considered.

Characterization of Elastic-plastic Material Properties for IMC Layer of ENEPIG by Using Reverse Algorithm

2010 ◽  
Author(s):  
Jong-Min Kim ◽  
Hyun-Boo Lee ◽  
Yoon-Suk Chang ◽  
Jae-Boong Choi ◽  
Young-Jin Kim ◽  
...  
Keyword(s):  
Material Properties ◽  
Plastic Material ◽  
Elastic Plastic ◽  
Elastic Plastic Material

Structural Integrity Research for Reactor Pressure Vessel Under In-Vessel Retention of a Core Melt

2016 ◽  
Author(s):  
Yongjian Gao ◽  
Yinbiao He ◽  
Ming Cao ◽  
Yuebing Li ◽  
Shiyi Bao ◽  
...  
Keyword(s):  
Pressure Vessel ◽  
Material Properties ◽  
Power Plants ◽  
Structural Integrity ◽  
Plastic Material ◽  
Plastic Region ◽  
Reactor Pressure Vessel ◽  
Elastic Plastic ◽  
Elastic Plastic Material ◽  
Reactor Pressure

In-Vessel Retention (IVR) is one of the most important severe accident mitigation strategies of the third generation passive Nuclear Power Plants (NPP). It is intended to demonstrate that in the case of a core melt, the structural integrity of the Reactor Pressure Vessel (RPV) is assured such that there is no leakage of radioactive debris from the RPV. This paper studied the IVR issue using Finite Element Analyses (FEA). Firstly, the tension and creep testing for the SA-508 Gr.3 Cl.1 material in the temperature range of 25°C to 1000°C were performed. Secondly, a FEA model of the RPV lower head was built. Based on the assumption of ideally elastic-plastic material properties derived from the tension testing data, limit analyses were performed under both the thermal and the thermal plus pressure loading conditions where the load bearing capacity was investigated by tracking the propagation of plastic region as a function of pressure increment. Finally, the ideal elastic-plastic material properties incorporating the creep effect are developed from the 100hr isochronous stress-strain curves, limit analyses are carried out as the second step above. The allowable pressures at 0 hr and 100 hr are obtained. This research provides an alternative approach for the structural integrity evaluation for RPV under IVR condition.

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