Methods Of Experimental Stress Analysis Research Articles

Analysis of Failures of Leaf Springs on the Continuous Casting Machines

At the first look very simple and for several hundred years used elastic element can be critical part in complex equipment where its failure invokes extraordinary high losses. In the paper is given a treatment for the solution of spring failure problem by experimental methods of stress analysis and resulting proposals for its final solution.

Application of Computational Methods and Methods of Experimental Stress Analysis for Determination of Lifespan of Pipe Yards

Compressor stations and their pipe yards are technological complexes that are loaded by dynamic loading during their operation. The result of such loading can be fatigue failure of structural member or whole system with serious consequences. One possibility of decreasing disadvantageous dynamic loading and increasing of lifespan is using vibroinsulation elements. The lifespan of structure is intimately connected to critical locations as pipe joints realized by welds. Residual lifespan is expressed on the basis of data gained by experiments according to appropriate standards.

Análisis de Tensiones mediante Elementos Finitos de una Válvula Esférica durante la Prueba Hidrostática, y su Verificación Experimental

The stress and deformation analysis in the body of a ball valve of diameter 8, class 600, during the hydrostatic test, using the finite elements method is done. The results are verified through experimental stress analysis method, using strain gauges. For the finite elements method the software Cosmos/M and information obtained during the experimental analysis were used. The experimental tests were carried out in a press type test machine, placing strain gauges in the body of the valve at certain points of interest. The values of deformation obtained allowed validating the application of the finite elements method.

Digital Photoelasticity: Advanced Techniques and Applications

Digital Photoelasticity: Advanced Techniques and Applications

The role and benefits of testing in product quality management

A key requirement for most engineered items is the ability to withstand the various loads that may be applied under conditions of use and of abuse that may reasonably be foreseen. To ensure that the strength requirement is satisfied, the designer must evaluate the levels of applied stress using appropriate calculation methods or by physical experiment. This paper considers the respective roles of computational and experimental methods of stress analysis, discussing the impact of changes in functional capability. Reference is made to the modern certification environment and the requirements of quality assurance, particularly related to the training of engineers and technicians in the necessary skills. The paper aims to present a balanced view of the role of experimental stress analysis, identifying areas where there are clear benefits. Some concluding comments are made regarding education, training and vocational qualifications.

Optical methods for complete stress determination — An experimental alternative to finite-element analysis

Experimental optics provides an interesting alternative to finite-element analysis (FEA) for estimating stress distribution in bodies subjected to load. Complete determination of the state of stress in a two-dimensional transparent model of the body was performed, using modern interferometry in combination with conventional photoelasticity. Stress concentrations and singularities may be evaluated in the same experimental set-up by means of the methods of caustics. The present approach eliminates the effect of limited optical quality of the model material, which is an advantage in engineering applications of the methods proposed. In contrast to most testing procedures using interferometry, this technique provides particularly simple handling of equipment and ease in evaluation. The paper describes an application to restorative dentistry of these methods of experimental stress analysis.

On the methodologies of stress analysis of composite structures

New, advanced experimental approaches, based on the principle of physical modelling of real events, have been applied to develop three new groups of experimental methods of stress analysis. They are briefly presented below and their efficacy is illustrated by examples: isodyne methods, strain gradient methods, and thermoelastic effect method. All three are nondestructive methods. The first two methods can be used to determine stress components or their spatial derivatives in materials that are transparent either in the visible band of electromagnetic radiation, or in the infrared, or--in principle--microwave band. The third group of methods is based on application of the thermoelastic effect which occurs in all bodies having non-zero values of the thermal expansion coefficient. These methods appear to be promising. For instance, they allow one to easily distinguish between elastic longitudinal and shear waves.

Experimental stress analysis at reactor and plant components using hard- and software

Abstract Increasing the reliability of pressure vessels the methods of experimental stress analysis are world-wide used for additional data. Components and software programs extend and improve the possibilities of the experimental stress analysis continuously. On-line display of stress results during applications is now possible. Field portable modular equipment with numerous instrument configurations meet the plant and field environmental constraints. The following paper describes a transportable quasistatic multipoint measuring unit with data processing and its use during the first pressure test of a nuclear reactor containment and further applications.

Photo-Orthotropic Elasticity: A New Technique For Stress Analysis Of Composites

This paper deals with the application of photoelastic methods to glass fiber reinforced plastics. The basic principles governing the photoelastic response in birefringent orthotropic composites are briefly reviewed. Then, three important aspects of photo-orthotropic elasticity, namely, photoelastic calibration, separation of principal stresses, and application to problems of engineering importance, are considered in detail. A new calibration specimen is proposed for determining the three independent photoelastic constants: an orthotropic half-plane subjected to a concentrated edge load. From the isochromatic response, the three stress-fringe values can be obtained by a least-squares procedure based on the theoretical stress distribution. Next, four methods of separating the principal stresses in birefringent composite models are proposed: the method of drilling small holes at the points of interest, the method of oblique incidence, the method of combining the transmitted photoelastic response with the reflected photoelastic response, and the method of birefringence dispersion.

Strain Measurement Using Grids

Determining strain with grids is one of the oldest and simplest methods of experimental stress analysis. Here, the method is reviewed. Various techniques that are used to print, record, and analyze grids are discussed, and the types of problems to which the grid method has been applied are presented.

The role of stress analysis in the design of force-standard transducers

The thesis proposed in this lecture is that solutions given by design equations representing the behavior of a structure or body will give the best approximation if an integral use is made of theoretical and experimental stress-analysis methods. To demonstrate the validity of the thesis, an investigation is described concerning a ring-shaped elastic element used to measure a force by relating it to diameter variations or to inner and outer surface strains.

Three-dimensional photoelasticity by stress freezing

Three-dimensional photoelasticity by the stress-freezing method has been considered to be one of the most powerful methods of experimental stress analysis. Its principles were well established more than thirty years ago, but its use outside the academic world has steadily declined. The reasons are cost and time needed to generate the desired information.

Optical Stress Analysis Using Moire Fringe And Laser Speckles

The paper reviews a series of experimental stress analysis methods using moire fringe and laser speckles. An analogy is drawn between the two groups of methods showing that moire methods are special cases of speckle methods. Difference between the two approaches are also pointed out. The experimental methods discussed include the analysis of plane stress and general three-dimensional problems, static and dynamic bending of plates, steady state vibration and transient stress problems.

Birefringence of non-linear viscoelastic-plastic polymers

The observation of photoelastic-plastic states of stress is well known as one of the valuable methods of experimental stress analysis in an infinitesimal elastic-plastic deformation. Photorheology is a comparatively new method for the measurement of non-steady inelastic deformation. Several investigations have been reported of birefringent properties in the elastic-plastic or in the viscoelastic-plastic region. In these, however, the birefringence relations are regarded as empirical or semi-empirical. A birefringence relation for a non-linear viscoelastic-plastic polymer is deduced mathematically from the view-point of continuum mechanics. The birefringent effect is the product of the principal strain difference and a scalar function of the invariants of the elastic and the viscoplastic strains.

State of stress around inhomogeneities by the method of caustics

Stress concentration fields around inclusions with or without singular points at the boundary under generalised plane stress conditions were studied by the method of caustics. A theoretical solution for the characteristics of caustics formed around inclusions of any shape in a homogeneous stress field as functions of the mechanical and optical properties of the constituent materials was developed. Experimental results were in absolute agreement with theoretical predictions. It was proved that the method can deal with inclusion problems not generally manageable by other methods of experimental stress analysis.

State of stress and strain in a rectangular belt pulled over a cylindrical pulley

This paper deals with the contact pressure between a belt and the pulley to which it transmits force and with the bending and membrane stresses in the belt. The anticlastic configuration of the belt is also taken into consideration. The commonly known simplified approximate analysis of the pressure, as well as the results of a more elaborated theory, are presented. Also given in the paper are the description and evaluation of several experimental stress analysis methods that can be used to solve the problem. Two– and three–dimensional photoelasticity, thickness measurements and electrical strain gauges were found to be the most practical approaches. The correlation of results obtained, using the theories and the experimental methods, is discussed. It is estimated that the peak contact pressure is 3–5 times that computed using the plane stress assumption. Results obtained will also have application in the design of wire–ropes or cables transmitting forces to sheaves or drums.

Use of Reinforced Epoxy Models to Design and Analyze Aircraft Structures

Aluminum-reinforced epoxy models are being used as precursors to prototype design in the development and modification of aircraft structures. In conjunction with experimental strain-measurement methods, these models provide extensive design information before engineering, tooling, and manufacturing expenses are incurred. Test applications, model fabrication, and experimental stressanalysis methods are discussed to illustrate the potential uses of the technique. Material characteristics such as time-modulus criteria together with the effects of model rework and transducer reinforcement are developed to acquaint the potential user with technical restraints.

The grid method

Determining strain with grids is one of the oldest and simplest methods of experimental stress analysis. Here, the method is reviewed. Various techniques that have been developed to print, record and analyze grids are discussed, and the types of problems to which the grid method has been applied are presented.

Paper 4: Analysis of Diesel Engine Structures with Special Reference to Traction Application

To judge the quality and safety of an engine structure today it is almost indispensable to employ experimental stress analysis methods. Merely testing prototype engines for locomotive service does not offer adequate security with regard to the danger of fatigue in the structure. This applies particularly to welded designs, because the scattering in production quality is an important factor here. The appropriate use of modern investigation methods is described with a number of examples. The decisive thing is to co-ordinate and exploit the available resources in design, research, and production so that optimum effectiveness is attained.

Summarized proceedings of a conference on stress analysis - Cranfield, September 1956

The Tenth Annual Conference of the Stress Analysis Group of The Institute of Physics was held at the College of Aeronautics on 19, 20 and 21 September, 1956, in conjunction with the Royal Aeronautical Society. Papers were read which could be divided into four main subjects: kinetic heating, extensometry and instrumentation, jet efflux and crack propagation, and the proceedings are summarized in this report. A review of recent improvements in methods of experimental stress analysis in the U.S.A. and Canada was given by Mr. A. F. C. Brown.