Jeong-Hwan Nam

Three-dimensional stress analysis of O-ring under uniform squeeze and internal pressure by photoelastic experimental hybrid method

Until now, it is known that stresses on the plane (y-z plane) perpendicular to the circumferential direction (x axis) of Oring exist and stresses on the plane (x-y plane and x-z plane) parallel to the circumferential direction of O-ring does not exist when O-ring is under uniform squeeze rate and internal pressure. But it was known that stresses of x-y plane and xz plane of O-ring under uniform squeeze and internal pressure were existed by this research. To analyze 3 dimensional stress distributions of O-ring under those loadings, stress distributions of every plane should be analyzed. Therefore, photoelastic experimental hybrid method for 3 dimensional stress distributions of O-ring under uniform squeeze and internal pressure were developed in this research. Photoelastic experimental procedures for 3 dimensional stress distributions of O-ring under those loadings were introduced. Stress distributions of O-ring under those loadings were analyzed by photoelastic experimental hybrid method developed in this research. Von Mises equivalent stresses at arbitrary point of O-ring under those loadings were analyzed.

A study on the development of loading device of photoelastic stress freezing method for O-ring stress analysis

There are O-rings for movement and for airtight in O-rings. O-ring for movement is used to protect to penetrate the dust or the alien substance into cylinder. O-ring for airtight is used to maintain airtight. Airtight of O-ring is controlled by squeeze rate and the gap between external diameter of groove and internal diameter of cylinder. Squeeze rate of O-ring is controlled by internal diameter of groove. Gap between external diameter of groove and internal diameter of cylinder is controlled by the external diameter of groove. Stresses of O-ring are depended on the squeeze rate, gap and internal pressure. O-ring for airtight is under uniform squeeze rate and internal pressure with constant gap. And then stress distributions are very complicated. Therefore stresses of O-ring are almost analyzed by experiment. To study the stress distributions of O-ring by experiment, 3-dimensional photoelastic experiment had better be used. To study stress distributions of O-ring by 3-dimensional photoelastic experiment, loading device is very important. Loading device should are functions, which uniform squeeze rate and internal pressure etc, can be applied, and the uniform squeeze rate can be controlled. Therefore, in this research, the loading device with functions explained above was developed. The validity of the loading device was confirmed by the stress distributions of O-ring, the configuration change of O-ring and the contact length of O-ring etc.. When squeeze rate is constant, the contact length of upper of the deformed O-ring is almost equal to that of lower of the deformed O-ring. When the internal pressure is applied to O-ring under uniform squeeze rate, the contact length of upper of O-ring is increased with the increment of the internal pressure by little. The contact length of lower of O-ring is constant irrespective of the increment of the internal pressure.

Stress Analysis of an Unpressurized Elstomeric O-Ring Seal Into a Groove by Photoelastic Experimental Hybrid Method

In this research, contact stresses of O-ring with uniform deformation in upper and lower direction are analyzed by photoelastic experimental hybrid method.

Application of the New Static Photoelastic Experimental Hybrid Method with New Numerical Method to the Plane Fracture Mechanics

Dynamic photoelastic experimental method [1,2] and photoelastic experimental analysis for othotropic material [3,4] have been widely studied [1,2] since 1950. Photoelastic experimental method has been widely applied to the static and dynamic fracture mechaics [5,6] since 1970. During this time, R.J. Sanford [7] suggested the non-linear least square method using Newton-Raphson numerical method with Gaussian elimination method. We have used this method and this conception for determination of stress intencity factor using photoelastic experimental method [8]. The non-linear least square method have been applied to the photoelastic experimental hybrid method which can be used to obtain the static and dynamic stress intensity factor and stress concentration factor [9,10,11]. The Newton-Raphson numerical method with Gaussian elimination method have been used in the non-lineal least square method for the photoelastic experimental method. In this research, the photoelastic experimental hybrid method with Newtion-Raphson numerical method is called old technique. However, old technique is often diverged and unstable in high stress distribution as vicinity of crack tip.

A Study on the Near-Field Stresses and Displacement of a Stationary Interfacial Crack in Two Dissimilar Isotropic Bimaterials

In many part of machines or structures that made of bimaterial bonded with two dissimilar materials, most failures occur at their interface. Therefore, the accurate analysis of fracture characteristics and the evaluation of mechanical strength for interfacial crack are essential when we design those structures. In this research, stress and displacement components in the vicinity of stationary interfacial crack tip in the two dissimilar isotropic bimaterials are established. Hereafter, the stress components established in this research can be applied to the photoelastic hybrid method which can be used to analyze the fracture behavior of the two dissimilar isotropic bimaterials.