Stress Analysis System Research Articles

Performance of the FAST system for stress analysis

A state-of-the-art thermographic system has been developed based on a 512×512 focal-plane array thermal imager. The system was primarily designed to perform stress analysis, but has applications in other areas where small cyclic temperature variations are encountered. A detailed analysis of its performance relative to an existing equipment (SPATE) revealed that, at least for low frequency applications, the proposed system out performs SPATE by some two to three orders of magnitude such that high-resolution area scans can now be achieved in minutes instead of hours. It is suggested that higher frequency applications (i.e., order of 102 Hz) can be achieved with more up-to-date imagers.

Thermal Stress Mitigating Properties for Graded Thermal Barrier Coatings of Gas Turbine.

A thermal stress analysis system has been developed, which enables convenient analysis of multilayered materials such as coatings. The analysis method of thermal stresses is based on the strain suppression technique and beam theory. In this study, the thermal stress properties of graded thermal barrier coatings were analyzed by focussing on the reductionability of thermal stress. Graded thermal barrier coatings with a surface layer of yttria-stabilized zirconia were chosen for the thermal stress analyses in the case of uniform heating and one-side heating with temperature difference. It was verified that the analysis technique based on equivalent thermal conductivity (=constant) was useful for optimizing the thermal barrier coatings. As a result, it was found that the effects of graded distribution on thermal stress mitigating properties were strongly dependent upon the graded thickness and heating condition.

Development of a Stress Analysis System for Spur Gear Tooth.

In order to automatically calculate the stress distribution of a spur gear tooth on the personal computer, a stress analysis system was developed. This system has four main functions : (1) gear cutting tool design, (2) gear tooth generation, (3) determination of the coordinates of tooth profile and the mesh pattern, and (4) use of a finite-element method for stress analysis and determination of calculated values. It is easy to design a rack cutter by the use of a simple CAD devised by the authors. The tooth profile generated using this cutter can be confirmed on the personal computer. The determination of the coordinates of tooth profile, the mesh pattern, and the boundary condition needed for the finite-element method is carried out automatically. Through an example, it is confirmed that this system is a useful tool for the design of the tooth profile which decreases maximum stress imposed on the fillet of spur gear.

Residual stress evaluation of coating films using Welding residual stress and deformation analysis system

Residual stress evaluation of coating films using Welding residual stress and deformation analysis system

A fully automatic stress-analysis system by using electro-optic modulation

This paper presents a new system for stress analysis, electro-optic modulation. The optical retardation resulting from stress is compensated for by induced birefringence in an electro-optic crystal under an applied voltage. When the compensation is complete the modulation signal changes, which signals that the measurement is complete. The sensitivity of measurement is higher than for other methods, easily less than λ/10000.

The SVI system for stress wave measurement and analysis of pile driving using the program SVIDYN1 : Tien, N T; Cuong, T V; Berggren, B; Moller, B Proc International Symposium on Computer and Physical Modelling in Geotechnical Engineering, Bangkok, 3–6 December 1986P161–167. Publ Rotterdam: A A Balkema, 1989

The SVI system for stress wave measurement and analysis of pile driving using the program SVIDYN1 : Tien, N T; Cuong, T V; Berggren, B; Moller, B Proc International Symposium on Computer and Physical Modelling in Geotechnical Engineering, Bangkok, 3–6 December 1986P161–167. Publ Rotterdam: A A Balkema, 1989

Computer-aided calculation of plate movements through the TECCOMP stress analysis system

Computer-aided calculation of plate movements through the TECCOMP stress analysis system

Stress analysis and support system design of the Central East ventilation shaft, South-Link railway, Taiwan : Shih, T; Keng, J; Hsiu, C Proc MMIJ/IMM Joint Symposium, Today's Technology for the Mining and Metallurgical Industries, Kyoto, 2–4 October 1989P181–190. Publ London: MMIJ/IMM, 1989

Stress analysis and support system design of the Central East ventilation shaft, South-Link railway, Taiwan : Shih, T; Keng, J; Hsiu, C Proc MMIJ/IMM Joint Symposium, Today's Technology for the Mining and Metallurgical Industries, Kyoto, 2–4 October 1989P181–190. Publ London: MMIJ/IMM, 1989

SVI system for stress wave measurement and analysis of pile driving using the program SVIDYN-I : Nguyen, T T; Cuong, T; Berggren, B; Moller, B Proc Symposium on Computer Aided Design and Monitoring in Geotechnical Engineering, Bangkok, 3–6 December 1986P506–518. Publ Bangkok: AIT, 1986

SVI system for stress wave measurement and analysis of pile driving using the program SVIDYN-I : Nguyen, T T; Cuong, T; Berggren, B; Moller, B Proc Symposium on Computer Aided Design and Monitoring in Geotechnical Engineering, Bangkok, 3–6 December 1986P506–518. Publ Bangkok: AIT, 1986

X-Ray Residual Stress Measurements in Notched Test Specimens

Abstract X-ray residual stress measurements were made in notched test specimens of 7475-T651 aluminum and annealed Ti-6Al-4V in a configuration designed to simulate fatigue testing in a tensile testing machine. An automated and portable X-ray stress analysis system with a position-sensitive proportional counter was used for making the measurements. Sources of error in the measurements resulted from counting statistics, grain size, and preferred orientation in the specimen, and the radius of curvature of the notch. The feasibility of in situ residual stress measurements during brief pauses in fatigue testing is demonstrated.

Stress analysis and design of metal-FRP bonded joints. 1st Report. Single lap joints.

It is important to get reasonable design indications for the joint structures of FRP with metallic materials. In this paper, a stress analysis system, which consists of FEM code, preprocessor and postprocessor, has been developed to design the joints. The stress distributions of a joint can be easily calculated by using this system. The elastic stress analyses of the metal-FRP single lap joints have been carried out to study the influences of the materials and sizes of the joints on the stress distributions. The stress concentrations at the end of the adhesive layer are much affected by the adhesive modulus and length of bond. The experimental results about the joint strength have been explained well by the calculated maximum equivalent stresses which arise at the end of the adhesive layer. The developed system is a useful tool for the design of bonded joints.

Stress analysis and design of metal-FRP bonded joints. (2nd report. T type joints).

In order to study the strength of the metal-FRP bounded joints, both of the finite element stress analyses and experiments have been carried out for T type bounded joints. It has been found that the fracture of the bonded joints, both the single lap joints and the T type joints, can be explained well by σmax which is the maximum equivalent stress in the adhesive layer. The fracture occurs when σmax reaches a critical value σf. σf is a constant for a specific bonded joint, and it can be estimated experimentally by the strength of a single lap joint. σmax can be calculated efficiently by the developed stress analysis system. Therefore, the strength of the bonded joints can be estimated by the criterion, σmax =σf, and the criterion is applicable to the structural design of the bonded joints.

Voice Stress Evaluators and Lie Detection

Proponents of vocal stress analysis systems argue that they are able to detect spoken deception by analysis of "stress" in the voice signal. Presumably, they do so by examining traces made by laryngeal microtremors which, they claim exist in the voice, are associated with stress, and ultimately are associated with lying. However, most research that seeks to identify the relationships between microtremors and laryngeal function has produced negative results, and data on the ability of voice analyzers to detect stress from speech--or to identify spoken deception--have been negative or "mixed" in nature. Since perspectives based on available results leave a number of questions unanswered, a series of experiments has been undertaken. The first was focused on the basic acoustic/temporal correlates of stress in voice (the subject of an earlier report), the second on examination of stress by commercial voice analyzers, and the third on the detection of relatively high-risk lies by this same type of voice analysis procedure. It was found that correct stress/nonstress identifications occurred only at chance levels; the lie/nonlie identification scores were quite similar with professional "examiners" performing at about the same level of accuracy as other auditors. The following review is divided into two parts: a history of the controversy and a presentation of the two cited experiments.

An Automatic System for Photoelastic Stress Analysis

An automatic system for photoelastic stress analysis is proposed. This system is composed of a photodiode, an amplifier, an A-D converter and a computer. Analogue information on isochromatic fringe patterns is converted to digital one by the photodiode the amplifier and the A-D converter. Thus, by using the microcomputer, we obtain stress distributions from these digital data of fringe patterns. We applied this system to determine stress distribution in circular and square plates subjected to concentrated loads, and obtained good results.

The automatic stress analysis system by photoelasticity.

In the previous paper, we invented the method to separate principal stresses by using only the isochromatic fringe patterns. In the present paper, by using this method, we propose an automatic stress analysis system by photo-elasticity. This system is composed of the photo diode, the amplifier, the A-D converter and the computer. The analogue information on the isochromatic fringe patterns is coverted to the digital one by the photo diode, the amplifier and the A-D converter. Thus, by using the microcomputer involved the program to separate the principal stresses, we obtain the stress distributions from these digital data of the fringe patterns. We apply this system to obtain the stress distributions of the circular and square plates subjected to concentrated loads, and show that the stresses obtained by the present system are in good agreement with those calculated theoretically or given by Frocht.

Advanced Analysis Techniques for the Optimum Design of Clean Rooms

This paper describes the application of advanced vibration analysis techniques and computational modeling to the design of microelectronics clean rooms. The ASAS (Atkins Stress Analysis System) and ASIST computer models were used to perform dynamic finite element analyses to determine the effects of transmitted structural forces on sensitive photolithographic equipment. The CAFE (Computer Aided Flow Evaluation) computer program was used to recirculate flow problems and evaluate the influences of representative obstructions on laminar air flow. Results of both analyses are presented.

Experience in the application of a finite element system to the analysis of complex prestressed concrete pressure vessels

The increasing geometric complexity of prestressed concrete pressure vessels (PCPVs) requires an accurate mathematical idealization of the shape of the structure. Finite elements of the isoparametric type provide one answer to this problem. The commercial availability of finite element analysis packages requires the designer to make a careful selection of a suitable package and adapt and extent that system to suit his particular needs. This paper discusses the application by Taywood Engineering Ltd, of the Atkins Stress Analysis System (ASAS) to the analysis of complex, multi-podded PCPVs. Details are given of the modelling process and the choice of grid fineness to be used. The preparation of data and the associated comprehensive checking procedures are described. The selection of material properties is of prime importance in finite element analysis and the dependence of the properties on temperature and creep is discussed together with the way in which results from only three analyses can be combined to provide the designer with the required information. Considerable emphasis is laid on the provision of small pre- and post-processing programs designed to remove the tedium of such large analyses and to leave the designer free to concentrate on the important engineering aspects of his design. The significance of the work lies in the fact that a suite of programs has been built around a general finite element system to satisfy the precise needs of a vessel designer. A design office tool has been produced which is economic in terms of the time and effort required in data preparation and assessment of results.

Calculation of P.C.P.V. prestressing forces

An integrated system of stress analysis programs is being developed at the Berkeley Nuclear Laboratories to assess the conditions in the plant operated by the C.E.G.B., and to study the effects of long-term operation. A knowledge of the body and boundary forces sustained by a Prestressed Concrete Pressure Vessel is required to completely evaluate the state of stress in the vessel. A computer program has been written to calculate these forces and completes the part of the stress analysis system devoted to P.C.P.V. appraisal.