Bounds on the Maximum Contact Stress of an Indented Elastic Layer

1971 ◽  
Vol 38 (3) ◽  
pp. 608-614 ◽  
Author(s):  
Y. C. Pao ◽  
Ting-Shu Wu ◽  
Y. P. Chiu

This paper is concerned with the plane-strain problem of an elastic layer supported on a half-space foundation and indented by a cylinder. A study is presented of the effect of the contact condition at the layer-foundation interface on the contact stresses of the indented layer. For the general problem of elastic indenter or elastic foundation, the integral equations governing the contact stress distribution of the indented layer derived on the basis of two-dimensional theory of elasticity are given and a numerical method of solution is formulated. The limiting contact conditions at the layer-foundation interface are then investigated by considering two extreme cases, one with the indented layer in frictionless contact with the half space and the other with the indented layer rigidly adhered to the half space. Graphs of the bounds on the maximum normal stress occurring in indented elastic layers for the cases of rigid cylindrical indenter and rigid half-space foundation are obtained for possible practical applications. Some results of the elastic indenter problem are also presented and discussed.

Author(s):  
Sherif Mohareb ◽  
Arndt Goldack ◽  
Mike Schlaich

Cable-stayed and extra-dosed bridges are today widely used bridge types. Recently, saddles have been used to deviate strands of cables in the pylons. Up to now the mechanics of strands on saddles are not well understood. It was found, that typical longitudinal contact stress distributions between strand and saddle show a strong nonlinearity and a high peak value around the detachment point, where the strand meets the saddle. This paper presents a procedure to analyse the longitudinal contact stress distribution obtained by FEM calculations: This contact stress can be idealised as a constant contact stress according to the Barlow's formula and a contact force at the detachment point due to the flexural rigidity of the bent tension elements. An analytical model is provided to verify this contact force. Finally, a formula is presented to calculate the maximum contact stress. This study provides the basis for further research on saddle design and fatigue of strands.


1997 ◽  
Vol 119 (3) ◽  
pp. 293-300
Author(s):  
T. Sawa ◽  
N. Higurashi ◽  
T. Hirose

A bolted connection consisting of a cover on a pressure vessel flange with a metallic flat gasket on raised faces is analyzed as a four-body contact problem using axisymmetrical theory of elasticity. The contact stress distribution, the load factor (the relationship between an increment of bolt axial force and an internal pressure), and the gasket properties (the gasket seating width and the moment arm) are examined. In the analysis, the cover is replaced with a finite solid cylinder. The metallic flat gasket, the flange, and the hub are replaced with finite solid cylinders. The effects of the stiffness and the thickness of various size gaskets on the contact stress distribution are obtained by numerical calculations. Experiments were carried out to obtain the load factor, the maximum stress produced in bolts, and the stress produced on the hub. The analytical results obtained are shown to be consistent with the experimental results.


2000 ◽  
Author(s):  
Toshiyuki Sawa ◽  
Tsuneshi Morohoshi ◽  
Akihiro Shimizu

Abstract In designing bolted joints, it is important to know the contact stress distribution which governs the clamping effect or the sealing performance and to estimate the load factor (the ratio of an increment in axial bolt force to an external load) from bolt design standpoint. The clamping force by bolts and the external bending moment are axi-asymmetrical loads and not many investigations have seen reported which treat axi-asymmetrical. In this paper, the clamping effect, and the load factor for the case of solid round bars with circular flanges, subjected to external bending moments, are analyzed as an axi-asymmetrical problem using the three-dimensional theory of elasticity. Experiments were carried out concerning the contact stress distribution, and the load factor for the external bending moment (a relationship between an increment in axial bolt force, and external bending moment). The analytical results were in fairly good agreement with the experimental ones.


2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
T. S. Ozsahin ◽  
O. Taskıner

The frictionless contact problem for an elastic layer resting on an elastic half plane is considered. The problem is solved by using the theory of elasticity and integral transformation technique. The compressive loadsPandQ(per unit thickness in direction) are applied to the layer through three rigid flat punches. The elastic layer is also subjected to uniform vertical body force due to effect of gravity. The contact along the interface between elastic layer and half plane is continuous, if the value of the load factor,λ, is less than a critical value, . In this case, initial separation loads, and initial separation points, are determined. Also the required distance between the punches to avoid any separation between the punches and the elastic layer is studied and the limit distance between punches that ends interaction of punches is investigated for various dimensionless quantities. However, if tensile tractions are not allowed on the interface, for the layer separates from the interface along a certain finite region. Numerical results for distance determining the separation area, vertical displacement in the separation zone, contact stress distribution along the interface between elastic layer and half plane are given for this discontinuous contact case.


1994 ◽  
Vol 116 (2) ◽  
pp. 207-215 ◽  
Author(s):  
T. Morohoshi ◽  
T. Sawa

This paper deals with the characteristics of a rectangular bolted connection of “T” shape with a gasket (filler plate), in which the flanges and a gasket (filler plate) are fastened with two bolts and nuts, and are then subjected to an external tensile load or a bending moment. The contact stress distribution which governs the sealing performance (clamping effect), the load factor (the relationship between an increment of axial bolt force and an external load), and the maximum stress produced in the bolt were analyzed by using a two-dimensional theory of elasticity as a three-body contact problem. Experiments were performed concerning the load factor and the maximum stress produced in the bolt. The analytical results are fairly consistent with experimental ones. The effects on the load factor and the contact stress distribution were examined for variation in Young’s modulus of different gaskets and the different distances between the bolt holes.


1996 ◽  
Vol 63 (1) ◽  
pp. 1-6 ◽  
Author(s):  
R. Y. S. Pak ◽  
F. Abedzadeh

This paper is concerned with the torsion of a rigid disk bonded to the bottom of a cylindrical indentation on an elastic half-space. By virtue of Fourier sine and cosine transforms, the mixed boundary value problem in classical elastostatics is shown to be reducible to a pair of integral equations, of which one possesses a generalized Cauchy singular kernel. With the aid of the theory of analytic functions, the inherent fractional-order singularity in the contact problem is rendered explicit. Illustrative results on the torsional stiffness of the base of the indentation and the corresponding contact stress distribution are presented for engineering applications.


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