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BEFORE discussing the machines and methods used, it is necessary to understand the fundamental laws which govern the testing of materials.

THE purpose of this paper is to examine the part that metal fatigue plays in the engineering of the helicopter, and to outline the methods used at present to estimate the safe fatigue life of the component parts of the helicopter.

The purpose of this paper is to forecast the reliable storage life of a certain kind of equipment under the normal stress level.

Through the stepping stress acceleration life test and the failure mechanism analysis, this paper aims to confirm the stress level for the stepping stress acceleration life test of a certain kind of equipment and establish the data processing mathematical model and storage life forecasting method.

The stress level for the stepping stress acceleration life test of a certain kind of equipment is confirmed and the data processing mathematical model and storage life forecasting method is established.

Availability of data is the main limitation affecting which model will be applied.

Useful advice for products' storage life forecasting.

The paper presents a new approach to product storage life estimation.

In the first two parts of this paper attention has been directed to determination of the stresses in a disk as dependent upon elastic and plastic strain, including creep effects which may occur at the rim region. The problem has so far, however, been treated without complication introduced by the blade fastenings and therefore, in effect, the disk has been investigated as far as the base of the blade grooves or slots. It has, however, been realized that the projections forming blade root fastenings present their own problems, differing from those of the disk, and these problems have been left to be dealt with in this third portion of the paper. Nevertheless, in Parts I and II the fact that the root fastenings applied an interrupted radial loading at the outside, and not a perfectly distributed load as assumed in the analysis, was not overlooked.

To obtain an optimal simple time‐step stress accelerated life test for the case involving pre‐specified censoring time. Such a test saves time and expenses over tests at normal conditions.

Most of the available literature on step‐stress accelerated life testing deals with the exponential and weibull distribution. The log‐logistic life distribution has been found appropriate for high reliability components.

The method developed has been illustrated using the data simulated from cumulative exposure log‐logistic step‐stress model with censoring time specified.

The model suggested is appropriate in the field of high reliability components such as insulation system.

The purpose of the investigation was to examine the tertiary creep and the creep fracture characteristics of an aluminium alloy to specification B.S.2L42, subject to complex stressing at 200 dog. C. The scope of the work involved seven pure torsion, pure tension, and combined tension and torsion creep tests, of durations between 300 hrs. and 3,000 hrs., on the aluminium alloy at 200 deg. C., and analysis of the results.

The purpose of this paper is to study the rheological behaviours of lead‐free solder pastes used for flip‐chip assembly applications and to correlate rheological behaviours with the printing performance.

A range of rheological characterization techniques including viscosity, yield stress, oscillatory and creep‐recovery tests were carried out to investigate the rheological properties and behaviours of four different solder paste formulations based on no‐clean flux composition, with different alloy composition, metal content and particle size. A series of printing tests were also conducted to correlate printing performance.

The results show that in the viscosity test, all solder pastes exhibited a shear thinning behaviour in nature with different highest maximum viscosity. The yield stress test has been used to study the effect of temperature on the flow behaviour of solder pastes. A decrease in yield stress value with temperature was observed. The results from the oscillatory test were used to study the solid‐ and liquid‐like behaviours of solder pastes. Creep‐recovery testing showed that the solder paste with smaller particle size exhibited less recovery.

More extensive research is needed to simulate the paste‐roll, aperture‐filling and aperture‐emptying stages of the stencil printing process using rheological test methods.

Implementation of these rheological characterization procedures in product development, process optimization and quality control can contribute significantly to reducing defects in the assembly of flip‐chip devices and subsequently increasing the production yield.

The paper shows how the viscosity, yield stress, oscillatory and creep‐recovery test methods can be successfully used to characterize the flow behaviour of solder pastes and also to predict their performance during the stencil printing process.

The purpose of this paper is to consider the general k level step-stress accelerated life test with the Rayleigh lifetime distribution for units subjected to stress under progressive Type-I censoring.

The parameter of this distribution is assumed to be a log-linear function of the stress, and a tampered failure rate model holds. The progressive Type-I censoring reduces the cost of testing. Due to constrained resources in practice, the test design must be optimized carefully. A numerical study is conducted to illustrate the optimum test design based on several four optimality criteria under the constraint that the total experimental cost does not exceed a pre-specified budget.

This paper compares unconstrained and constrained optimal k level step-stress test. Based on the results of the simulation study, the cost constraint reduces cost and time of the test and it also, in the most cases, increases the efficiency of the test. Also, the T-optimal design is lowest cost and time for testing and it is found more optimal in both conditions.

In this paper, various optimization criteria for selecting the stress durations have been used, and these criteria are compared together. Also, because of affecting the stress durations on the experimental cost, the author optimize under the constraint that the total experimental cost does not exceed a pre-specified budget. The efficiency of the unconstrained test in comparison with constrained test is discussed.

IT is well known that many materials, including wrought and heat‐treated duralumin‐type alloys, when subjected to fatigue tests in machines employing different stressing and straining actions, may give consistent results under each set of conditions, but the results will not agree from one set of conditions to another. Differences in the form and size of the test piece may also have an effect on the results of fatigue tests. This note discusses certain aspects of the problem of why such differences in test conditions can cause differences in the results of fatigue tests.

There is limited discussion in the literature of the problems associated with constructing stress tests. The Credit Crunch has revealed that attention simply to haircuts to asset values and resulting margin calls is insufficient. The purpose of this paper is to explore additional avenues for stress testing.

The paper is largely discursive.

Stress tests must look into the debt position of the firm, as well as its position and credit exposures. Not only the volume of debt but its maturity structure, callability and the indentures attached to it are extremely important.

The paper is geared more toward management and practitioners than to academic researchers. Implications for the analysis of corporate strategy are significant.

Stress testing is essential to the confident continuance of firms.

So much of the work in this area is proprietary and so little has been published on it.