Plastic Waves of Combined Stresses Due to Longitudinal Impact of a Pretorqued Tube—Part 2: Comparison of Theory With Experiment

1970 ◽  
Vol 37 (4) ◽  
pp. 1113-1120 ◽  
Author(s):  
J. Lipkin ◽  
R. J. Clifton
Keyword(s):  
Strain Rate ◽  
Numerical Solutions ◽  
Plastic Material ◽  
Material Behavior ◽  
Complete Agreement ◽  
Longitudinal Impact ◽  
Final State ◽  
Theoretical Predictions ◽  
Constant State ◽  
Elastic Plastic Material

The strain-time profiles of the experiments described in Part 1 are compared with numerical solutions based on a rate-independent theory for an isotropic work-hardening, elastic-plastic material. As discussed in Part 1, complete agreement between theory and experiment is not possible because the constant state regions predicted by the theory are not observed. In addition, the calculations lead to a final state of shear strain that is considerably greater than the measured value. Also, the magnitude of the observed jump in strain rate at an unloading wave does not agree with the theoretical predictions. The absence of constant state regions and the discrepancy in the jump at unloading waves are shown to be explainable in terms of the inadequacy of the assumption of strain rate-independent material behavior.

Fatigue Evaluation in Mixing Zones: Comparison of Different Criteria of Fatigue

2008 ◽  
Author(s):  
J. M. Stephan ◽  
C. Gourdin ◽  
J. Angles ◽  
S. Quilici ◽  
L. Jeanfaivre
Keyword(s):  
Fatigue Damage ◽  
Thermal Stresses ◽  
Plastic Material ◽  
Material Behavior ◽  
Damage Evaluation ◽  
Elastic Plastic ◽  
Different Types ◽  
Elastic Plastic Material ◽  
Fatigue Evaluation

The distribution of unsteady temperatures in the wall of the 6" FATHER mixing tee mock-up is calculated for a loading configuration: The results seem realistic even if they are not still very accurate (see paper PVP2005-71592 [11]). On this basis, thermal stresses are evaluated for elastic and elastic-plastic material behavior. Then, different types of fatigue criteria are used to evaluate the fatigue damage. The paper develops a brief description of the criteria, the corresponding fatigue damage evaluation and attempts to explain the differences.

A Continued Evaluation of the Role of Material Hardening Behavior for the NeT TG1 and TG4 Specimens

2014 ◽  
Author(s):  
David J. Dewees ◽  
Phillip E. Prueter ◽  
Seetha Ramudu Kummari
Keyword(s):  
Structural Integrity ◽  
Plastic Material ◽  
Critical Factor ◽  
Material Model ◽  
Standard Test ◽  
Material Behavior ◽  
Weld Residual Stress ◽  
Hardening Models ◽  
Elastic Plastic Material

Modeling of cyclic elastic-plastic material behavior (hardening) has been widely identified as a critical factor in the finite element (FE) simulation of weld residual stresses. The European Network on Neutron Techniques Standardization for Structural Integrity (NeT) Project has provided in recent years both standard test cases for simulation and measurement, as well as comprehensive material characterization. This has allowed the role of hardening in simulation predictions to be isolated and critically evaluated as never before possible. The material testing information is reviewed, and isotropic, nonlinear kinematic and combined hardening models are formulated and tested. Particular emphasis is placed on material model selection for general fitness-for-service assessments, as it relates to the guidance for weld residual stress (WRS) in flaw assessments of in-service equipment in Annex E of the FFS standard, API 579-1/ASME FFS-1.

Failure of an Impulsively-Loaded Composite Steel/Polymer Plate

2006 ◽  
Author(s):  
JongMin Shim ◽  
Tomasz Wierzbicki
Keyword(s):  
Analytical Solution ◽  
Strain Rate ◽  
Composite Plate ◽  
Numerical Solutions ◽  
Plastic Material ◽  
Structural Parameters ◽  
Thick Layer ◽  
Composite Plates ◽  
Average Strain ◽  
Composite Steel

The concept of spraying a thick layer of a polymeric material onto a metal plate has recently received considerable interest in many civilian and military applications. There are numerous analytical and numerical solutions for single thin (membrane) plates made of either a steel or an elastomer. However, solutions for a composite plate made of both of the above constituents are lacking. The objective of the present paper is to formulate a model for a composite steel/elastomer plate, derive an analytical solution for the plate subjected to impulsive loading and compare it with a more exact numerical solution. It is assumed that the circular plate is fully clamped around its periphery, and it is loaded by a uniformly distributed transverse pressure of high intensity and short duration. The pressure imparts an initial impulse which is proportional to the initial transverse velocity of the plate. As an example, DH-36 is used for a steel backing plate while polyurea is chosen as a coating. The analytical model is developed where the steel layer is treated as a rigid perfectly-plastic material. The magnitude of flow stress is adjusted iteratively according to the calculated magnitude of average strain. On the other hand, a linear elastic material is assumed for the polyurea with elastic modulus in the tensile range calculated from the Arruda-Boyce model. The magnitude of the average strain rate was relatively low, about 100 sec-1; therefore, the effect of strain rate is not considered in this paper. A comprehensive parametric study was performed by varying several material and structural parameters in the model. A closed-form analytical solution was compared with the results of detailed FE simulations of composite plates, and good correlation is obtained. It was found that the polyurea coating could improve the failure resistance of the composite plate by 20 % provided that the thickness of the coating is 5 – 10 times larger than the plate.

Stress and Buckling of Internally Pressurized, Elastic-Plastic Torispherical Vessel Heads—Comparisons of Test and Theory

1977 ◽  
Vol 99 (1) ◽  
pp. 39-53 ◽  
Author(s):  
D. Bushnell ◽  
G. D. Galletly
Keyword(s):  
Mild Steel ◽  
Large Deflection ◽  
Plastic Material ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Test Results ◽  
Elastic Plastic ◽  
State Of Stress ◽  
Elastic Plastic Material ◽  
Good Agreement

Several aluminum and mild steel torispherical heads were tested by Galletly and by Kirk and Gill and subsequently analyzed by Bushnell with use of the BOSOR5 computer program. The thinnest specimens buckled at pressures for which part of the toroidal knuckle was stressed well beyond the yield point. The analysis includes large deflection effects, nonlinear material behavior, and meridional variation of the thickness. The calculated strains in the thicker specimens agree reasonably well with the test results, but the calculated prebuckling strains in the thinnest specimens are generally greater than the values measured in the torodial knuckle after the onset of plastic flow. Reasonably good agreement between test and theory is obtained for the buckling pressures of aluminum specimens, but the calculated buckling pressures for mild steel specimens are much lower than the observed values, a discrepancy that is attributed to circumferentially varying thickness and possible inability of the analytical model of the elastic-plastic material to predict accurately the state of stress in the toroidal knuckle where loading is nonproportional once yielding has occurred.

Analysis of Tension and Bending Response to Characterize Elastic-Plastic Material Behavior

2017 ◽  
Author(s):  
Don Metzger ◽  
Wolf Reinhardt
Keyword(s):  
Plastic Material ◽  
Load Capacity ◽  
Material Behavior ◽  
Material Degradation ◽  
Load Curve ◽  
Bending Mode ◽  
Elastic Plastic Material ◽  
Component Loading ◽  
The Relationship ◽  
Bending Response

The integrity of components can be affected by certain material degradation mechanisms that cause a loss of ductility. In cases where the component loading is primarily in bending, a loss of ductility can significantly reduce the load capacity. Material degradation may be determined by component testing involving the bending mode. In such cases, characterizing the material response in terms of yield stress, ultimate stress and failure strain is complicated by the nature of the load curve due to bending. The objective of this work is to examine in detail the relationship between tensile and bending response, with particular attention to the condition of decreasing ductility.

On the Nature of Normality of Plastic Strain Rate and Convexity of Yield Surfaces in Plasticity

1975 ◽  
Vol 42 (1) ◽  
pp. 61-66 ◽  
Author(s):  
P. M. Naghdi ◽  
J. A. Trapp
Keyword(s):  
Plastic Strain ◽  
Strain Rate ◽  
Plastic Material ◽  
Plastic Strain Rate ◽  
Rigid Plastic ◽  
Elastic Plastic ◽  
Rigid Plastic Material ◽  
Yield Surfaces ◽  
Elastic Plastic Material ◽  
Special Case

Within the scope of the purely mechanical theory of plasticity, in a previous paper we have derived two inequalities which place restrictions on the constitutive equation for the rate of plastic strain in a finitely deformed elastic-plastic material. Here we take up the matter further, elaborate on the nature of the previously derived restrictions and obtain some additional results pertaining to the normality of the plastic strain rate and convexity of yield surfaces. Although in the main our discussions are carried out in the context of finite deformation, the nature of the restrictions for infinitesimal deformation is also examined. A special case of an elastic-plastic material in which the stress response is characterized by the stress rate and that of a rigid-plastic material are given detailed attention.

Elastic-Plastic Analysis of Stresses and Initiation of Cracks in a Ceramic Coating Under Indentation by an Elastic Sphere

1998 ◽  
Vol 120 (3) ◽  
pp. 463-469 ◽  
Author(s):  
K. Hayashi ◽  
F. Yuan
Keyword(s):  
Ceramic Coating ◽  
Plastic Material ◽  
Circumferential Stress ◽  
Material Behavior ◽  
Elastic Sphere ◽  
The Finite Element Method ◽  
Elastic Plastic ◽  
Formation Of Cracks ◽  
Elastic Plastic Material ◽  
Radial Cracks

The elastic-plastic contact problem of a ceramic coating on a half-space indented by an elastic sphere is solved by the use of the finite element method under a variety of conditions. An elastic-plastic material behavior with isotropic strain hardening was employed. Results for stresses, during loading and after unloading, on the surface and along the axis of symmetry are presented and formation of cracks is discussed in detail, emphasizing the influence of the thickness of coating. It is shown that the circumferential stress on the surface of the coating is highly tensile so that radial cracks are induced for a sharp indenter. But, for a blunt indenter, the radial stress is tensile and is always larger than the circumferential stress, leading to the formation of circumferential cracks. It is also shown that, in the case of a sharp indenter, radial cracks can be induced during unloading.

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