Elastic–plastic contact force history and response characteristics of circular plate subjected to impact by a projectile

2007 ◽  
Vol 23 (4) ◽  
pp. 415-425 ◽  
Author(s):  
L. B. Chen ◽  
F. Xi ◽  
J. L. Yang
Keyword(s):  
Circular Plate ◽  
Contact Force ◽  
Elastic Plastic ◽  
Response Characteristics

Approximate Macroscale Constitutive Relations Using a Finite Element Based Constitutive Equations for Microscale Contact

2008 ◽  
Author(s):  
Ali Sepehri ◽  
Kambiz Farhang
Keyword(s):  
Finite Element ◽  
Contact Force ◽  
Rough Surfaces ◽  
Constitutive Relations ◽  
Cumulative Effect ◽  
Element Model ◽  
Tangential Component ◽  
Total Force ◽  
Asperity Contact ◽  
Elastic Plastic

Three dimensional elastic-plastic contact of two nominally flat rough surfaces is considered. Equations governing the shoulder-shoulder contact of asperities are derived based on the asperity-asperity constitutive relations from a finite element model of their elastic-plastic interaction. Shoulder-shoulder asperity contact yields a slanted contact force consisting of both tangential (parallel to mean plane) and normal components. Multiscale modeling of the elastic-plastic rough surface contact is presented in which asperity-level FE-based constitutive relations are statistically summed to obtain total force in the normal and tangential direction. The equations derived are in the form of integral functions and provide expectation of contact force components between two rough surfaces. An analytical fusion technique is developed to combine the piecewise asperity level constitutive relations. This is shown to yield upon statistical summation the cumulative effect resulting in the contact force between two rough surfaces with two components, one in the normal direction and a half-plane tangential component.

An Extension of CEB Elastic-Plastic Contact Model

2007 ◽  
Author(s):  
A. Sepehri ◽  
K. Farhang
Keyword(s):  
Contact Force ◽  
Tangential Force ◽  
Three Dimensional ◽  
Tangential Direction ◽  
Asperity Contact ◽  
Force Component ◽  
Normal Contact ◽  
Elastic Plastic ◽  
Force Components ◽  
Plastic Parts

Three dimensional elastic-plastic contact of two nominally flat rough surfaces is by developing the equations governing the shoulder-shoulder contact of asperities based on the Chang, Etsion and Bogy (CEB) model of contact in which volume conservation is assumed in the plastic flow regime. Shoulder-shoulder asperity contact yields a slanted contact force consisting of both tangential (parallel to mean plane) and normal components. Each force component comprises elastic and elastic-plastic parts. Statistical summation of normal force components leads to the derivation of the normal contact force for the elastic-plastic contact akin to the CEB model. Half-plane tangential force due to elastic-plastic contact is derived through the statistical summation of tangential force component along an arbitrary tangential direction.

Stress Relaxation in Press-Fitted Joints

1976 ◽  
Vol 98 (1) ◽  
pp. 137-140 ◽  
Author(s):  
R. P. Goel
Keyword(s):  
Steady State ◽  
Stress Relaxation ◽  
Circular Plate ◽  
Contact Force ◽  
Radial Stress ◽  
Printed Circuit Boards ◽  
Stress Component ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Relaxation Characteristics

When contact pins, wire wrap posts, etc., are press fitted into printed circuit boards, the contact force at the interface of a post and plate relaxes with time. Much of the relaxation of the contact force occurs immediately after the connection has been made. Theoretical estimates on the reduction in contact force until a steady state (a steady state is assumed to be reached when the stress rates become 1 percent of their initial values) is reached are presented. Since most of the relaxation of the radial stress component occurs in the vicinity of the hole, the effect of adjacent joints on the relaxation characteristics of a joint are neglected. And, therefore, only an idealized geometry of a thin circular plate with a single press-fitted hole is considered.

Closure Equations for CEB Elastic-Plastic Contact

2007 ◽  
Author(s):  
A. Sepehri ◽  
K. Farhang
Keyword(s):  
Closed Form ◽  
Integral Equations ◽  
Contact Force ◽  
Elastic Plastic ◽  
Approximate Function ◽  
The Mean ◽  
Contact Relation ◽  
Explicit Relation ◽  
Force Accuracy ◽  
Approximate Equations

The CEB elastic-plastic contact of nominally flat rough surfaces based on conservation of volume during plastic flow was forwarded by Chang, Etsion and Bogy [1]. The CEB model presents contact force as integral functions of the mean plane separation. A closed-form approximate function providing an explicit relation between contact force and surface parameters and mean plane separation would be desirable for several reasons. First, it facilitates implementation of the contact relation in the dynamics of mechanical system and, second, it provides expediency and efficiency for calculation of contact force when repetitive computation of the contact force is required. This paper presents closed-form approximate equations expressing contact force explicitly as a function of critical interference and mean plane separation. Two alternative approximate equations are provided. The first equation, in simpler form, is shown to yield error within six percent (6%) of the exact integral equations. The second form of approximate equations provides contact force accuracy within 0.1 percent of the original integral equations.

scholarly journals A Finite Element-Based Elastic-Plastic Model for the Contact of Rough Surfaces

2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
Ali Sepehri ◽  
Kambiz Farhang
Keyword(s):  
Finite Element ◽  
Contact Force ◽  
Contact Area ◽  
Rough Surfaces ◽  
Constitutive Relations ◽  
Element Model ◽  
Tangential Component ◽  
Asperity Contact ◽  
Elastic Plastic ◽  
Force Components

Three-dimensional elastic-plastic contact of two nominally flat rough surfaces is considered. Equations governing the shoulder-shoulder contact of asperities are derived based on the asperity constitutive relations from a finite element model of the elastic-plastic interaction proposed by Kogut and Etsion (2002), in which asperity scale constitutive relations are derived using piecewise approximate functions. An analytical fusion technique is developed to combine the piecewise asperity level constitutive relations. Shoulder-shoulder asperity contact yields a slanted contact force consisting of two components, one in the normal direction and a half-plane tangential component. Statistical summation of the asperity level contact force components and asperity level contact area results in the total contact force and total contact area formulae between two rough surfaces. Approximate equations are developed in closed form for contact force components and contact area.

Closed-Form Equations for Three Dimensional Elastic-Plastic Contact of Nominally Flat Rough Surfaces

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Ali Sepehri ◽  
Kambiz Farhang
Keyword(s):  
Closed Form ◽  
Contact Force ◽  
Rough Surfaces ◽  
Tangential Force ◽  
Three Dimensional ◽  
Tangential Direction ◽  
Asperity Contact ◽  
Force Component ◽  
Elastic Plastic ◽  
Functional Forms

Approximate closed-form equations governing the shoulder-shoulder contact of asperities are derived based on a generalization by Chang, Etsion, and Bogy. The work entails the consideration of asperity shoulder-shoulder contact in which the volume conservation is assumed in the plastic flow regime. Shoulder-shoulder asperity contact gives rise to a slanted contact force comprising tangential and normal components. Each force component comprises elastic and plastic terms, which upon statistical summation yields the force component for the elastic and plastic forces for the contact of two rough surfaces. Half-plane tangential force due to elastic-plastic contact is derived through the statistical summation of tangential force component along an arbitrary tangential direction. Two sets of equations are found. In the first set of equations the functional forms are simpler and provide approximation of contact force to within 9%. The second set is enhanced equations derived from the first set of approximate equations that achieve an accuracy of within 0.2%.

Elastic-Plastic Microcontact Model for Elliptical Contact Areas and Its Application to a Treillis Point in Overhead Electrical Conductors

2011 ◽  
Vol 133 (1) ◽  
Author(s):  
Frédéric Lévesque ◽  
Sylvain Goudreau ◽  
Louis Cloutier
Keyword(s):  
Contact Force ◽  
Critical Points ◽  
Contact Area ◽  
Transmission Lines ◽  
Electrical Transmission ◽  
Contact Areas ◽  
Elastic Plastic ◽  
Elliptical Contact ◽  
Rigid Plane ◽  
Electrical Conductors

Aeolian vibrations represent a threat to the integrity of electrical transmission lines. The fretting fatigue of conductors is thus a major concern. The modelization of the contact conditions at critical points is an important tool in assessing the life of conductors. Treillis points around the last point of contact between the conductor and the pieces of equipment are such critical points. We observe a fully plastic contact condition at these points. Finite element results for the contact between an ellipsoid and a rigid plane and between two wires at different angles are compared with an elastic-plastic microcontact model for elliptical contact areas. These numerical results are then compared with experimental ones for the contact between two wires of a conductor (ACSR Bersfort), showing a very similar relationship between the contact force and the observed contact area. We have a good correlation between the microcontact model and the finite elements ones in the fully plastic contact regime on both the contact area and the contact force for a given interference between bodies. The use of the elastic-plastic microcontact model for elliptical contacts presented in this paper proves to be a strong tool in getting a better understanding of the mechanical behavior at those critical points.

scholarly journals Seismic Response Characteristics of Stabilizing Pile Based on Elastic-Plastic Analysis

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Honglue Qu ◽  
Ying Liu ◽  
Hao Luo ◽  
Huanguo Hu ◽  
Qindi Hu
Keyword(s):  
Plastic Zone ◽  
Seismic Response ◽  
Ground Motion ◽  
Seismic Design ◽  
Design Parameters ◽  
Plastic State ◽  
Elastic Plastic ◽  
Stabilizing Pile ◽  
Response Characteristics ◽  
Plastic Analysis

Stabilizing pile is widely used in the landslide controlling projects and shows excellent seismic performance under the action of earthquake. Therefore, in order to improve seismic design theory, it is of importance to study the seismic response characteristics of stabilizing pile based on elastic-plastic analysis. In view of this, elastic-plastic constitutive model was established to deduce the plastic zone of stabilizing pile. Based on elastic-plastic analysis, the seismic response characteristics and the influence of different section sizes, material strengths, and peak ground motion acceleration (PGA) were analyzed by ANSYS 3D. Resultantly, the elastic-plastic fourth-order tensor Cijklep was deduced, which can be used to calculate plastic strain of stabilizing pile under loading. Compared with Chinese code, the material of stabilizing pile working with elastic-plastic state will be decreased under the same section size and the same property. Furthermore, stabilizing pile is in the elastic stage at the beginning under the action of earthquake. With the increase of ground motion time, the section starts to exhibit elastic-plastic state and then the plastic zone expands gradually. Finally, the plastic zone runs through the whole section, resulting in the performance loss of the pile. In addition, under the different design parameters, pile shows different seismic response characteristics; namely, changing these parameters reasonably can improve the seismic design.

A Finite Element Model for Spherical Debris Denting in Heavily Loaded Contacts

2004 ◽  
Vol 126 (1) ◽  
pp. 71-80 ◽  
Author(s):  
Young Sup Kang ◽  
Farshid Sadeghi ◽  
Mike R. Hoeprich
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Friction Coefficient ◽  
Aspect Ratio ◽  
Finite Element Model ◽  
Contact Force ◽  
Material Properties ◽  
Element Model ◽  
Friction Coefficients ◽  
Elastic Plastic

The objective of this study is to develop models to investigate the effects of contaminants (debris denting process) in heavily loaded rolling and sliding contacts. A dynamic time dependent finite element model (FEM) was developed to determine the elastic-plastic deformation and contact force generated between the mating surfaces and a spherical debris as debris passes through the contact region. The FEA model was used to obtain the effects of various parameters such as debris sizes, material properties, friction coefficients, applied loads, and surface speeds on the elastic-plastic deformation and contact force of the system. The FEM was used to predict debris and mating surfaces deformations as a function of debris size, material properties, friction coefficient, applied load, and surface speed. Using the FEM, a parametric study demonstrated that material properties (i.e., modulus of elasticity, yield strength, ultimate strength and Poisson’s ratio) and friction coefficients play significant roles on the height and width of dents on the mating surfaces. For lower friction coefficients μd<0.3 the debris and mating surfaces slip more easily relative to one another and therefore the debris has lower aspect ratio. As friction coefficient is increased the debris and mating surfaces stick to one another and therefore the debris deforms less and has higher aspect ratio. The results indicate that the pressure generated between the debris and mating surfaces is high enough to plastically deform the debris and mating surfaces and cause a permanent dent on the surfaces and cause residual stresses around the dent. Based on the FEM results, a dry contact model (DCM) was developed to allow similar analyses as the FEM, however, in significantly shorter computational time.

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