Strain Analysis Method Research Articles

The stress concentration in keyways when torque is transmitted through keys

The stress-concentration factor for keyways is obtained by the electroplating method of strain analysis which was recently developed in Japan. The stresses in keyways are examined under most practical conditions. The shaft to be examined is set in a boss and fixed with a key so that the torque is wholly transmitted to the test piece through the key. To obtain the limit value for a shaft twisted only through a key, the fitting is devised so as to minimize the surface friction at the fitted portion. The results are compared to those reported previously by other authors in which local effects of the key are ignored.

Improvement of Moire and Grid Methods of Plastic Strain Analysis and Their Application to Extrusion of Metals

Improvement of Moire and Grid Methods of Plastic Strain Analysis and Their Application to Extrusion of Metals

Experimental methods of large strain analysis

It is claimed in this paper that strain distributions in many two-dimensional large deformation problems can be obtained in a relatively easy manner using either grids, moire, photoelasticity, thickness measurements, or combinations of these methods. Considerations on the advantages and limitations of each of these methods are made. As an illustration, grids, moire and photoelasticity are applied to the solution of certain phases of the problem of the determination of strains in a ring subjected to large diametral compression.

Moiré method of strain analysis

Moiré method of strain analysis

The moiré grid-analyzer method for strain analysis

The moiré grid-analyzer method for strain analysis

A method of elastic-plastic plane stress and strain analysis

Plane boundary value problems are formulated in terms of an elastic-plastic stress function and the plastic strains. The governing relation is a non-homogeneous biharmonic equation. It is applicable to the total or deformation theories and to the incremental theories. Sample problems illustrate the practicality of the method.

The moiré grid-analyzer method for strain analysis

The complete state of strain throughout an extended field can be determined from a single photograph by the moire grid-analyzer method. Grids are used for the active, or specimen screen, and for the rigid analyzer screen. Hence, two families of moire fringes appear simultaneously, providing displacements inx andy directions throughout the field.

Photoelastic study of the interaction between a plane stress wave and a rigid circular inclusion

In the research programme described in this paper an experimental solution was obtained for the stress distribution around a rigid circular inclusion in a large plate during passage of a plane stress wave. The stress wave was generated by passing an air shock of fast rise and slow decay along an edge of the plate with a shock tube. The experimental methods used for the study were dynamic photoelasticity complemented with the moire method of strain analysis. A transparent, low-modulus, birefringent, urethane rubber was used as the model material.Transient free-field stresses were determined in the plate, at the inclusion location, before the inclusion was inserted. The magnitudes of these stresses at various times during passage of the stress wave were introduced into the static theoretical solution of Goodier to obtain what is referred to as equivalent ‘static’ stress distributions on the boundary of the inclusion. These distributions were then compared with the dynamic distributions obtained directly fro...

Stress Distribution on the Boundary of a Circular Hole in a Large Plate Due to an Air Shock Wave Traveling Along an Edge of the Plate

In the research program reported in this paper an experimental solution was obtained for the stress distribution around a circular hole in a large plate during passage of a pressure wave. The pressure wave was generated by passing an air shock wave of fast rise and slow decay along an edge of the plate with a shock tube. The experimental method used for the study was dynamic photoelasticity complemented with the moire method of strain analysis. A transparent, low-modulus, birefringent, urethane rubber was used as the model material. Transient free-field stresses were determined in the plate, at the hole location, prior to machining the hole. These stresses were introduced in the classical Kirsch solution to obtain what is referred to as a static stress distribution around the boundary of the hole. This stress distribution was compared with the dynamic stress distribution obtained directly from photoelastic data. The free-field stresses were also introduced in the theoretical solution by Baron and Matthews to obtain the maximum tangential stress on the boundary of the hole. The theoretical results are in good agreement with the experimentally determined maximum tangential stress. The results also indicate that the dynamic stress-concentration factor is initially lower than the static one, exceeds is at a later time, and finally approaches it asymptotically.

Photograting 法による実験的ひずみ解析方法

Previously, the authors reported results obtained through the usual method of experimental strain analysis by photograting, applying the method to two-dimensional problems (using experimental values of interference fringe spacing and inclination), and also suggested a new method of experimental strain analysis by photograting. In the new method, the inclinations of two interference fringe patterns with the reference axis ∅+ and ∅-, where the master screen axis makes the angle +θ and -θ respectively with the reference axis, are used.In this paper, two methods of experimental strain analysis by photograting are presented and the accuracy of strain measurement by the new method is described and discussed.It has been clarified that the new method makes strain measurement easier and helps to improve the accuracy of measurement. It was also concluded that the angle θ should be 2° for strains less than 1% and 3° for about 1% strain and with increasing strain greater θ's must be adopted to get high accuracy.

Resistance-Wire Strain Gauges

It is odd to think that the resistance-wire strain gauge could have been put to use some 40 years ago, about the time of the first filament-wire lamp and the thermionic valve. The physical principles involved were already known. Kelvin had measured the resistance of wires in tension, there were galvanometers in plenty, and even crude valve amplifiers existed. It only really remained for someone to put two and two together. Instead we had to wait until the necessity of stressed-skin construction forced the hand of the engineer into seeking a more effective method of strain analysis than the old empirical ways.