Papers by Keyword: Testing Method

Abstract: Determining interlayer shear modulus of composite materials by the method of three-point transverse bending is considered, and Timoshenko approaches to estimating the shear strains in this type of loading are assessed. It is shown that these approaches make it possible to determine the shear component of beam deflection with an accuracy acceptable for practice in testing them in three-point transverse bending, but only for isotropic materials. For anisotropic materials, they are unacceptable. These approaches are also unacceptable for determining the shear modulus of isotropic and anisotropic materials. Based on the data obtained as a result of the study, a simple and economical method for determining the shear moduli in the three-point transverse bending is proposed. This method was tested on both isotropic and composite materials with different reinforcement structures. Results showed a good agreement between the calculated and experimental values of the shear moduli for all the materials considered, which confirmed that the method proposed method can be used in practice.

Abstract: A heat sink is a cooling device that transfers the dissipated heat away from electronics to the surroundings. The testing method presented in the paper applies the nonequilibrium thermodynamic analysis of heat sink cooling curves. Here, the heat sink temperature time course is measured by using a thermal imager. The used thermal imager Flir T-640 takes single shots with recording of images. The proposed method validation test was performed on a selected heat sink. By analyzing the heat sink cooling curves, it is possible to obtain courses of the heat power and the heat sink surface to ambient thermal resistance. The presented testing method also enables a thermal analysis to distinguish between the convective and radiative components of heat transfer.

Abstract: This paper investigates the fatigue results in low cycle fatigue region obtained from a miniaturized specimen having a 6mm gage length, 3mm diameter and 55mm total length. Fatigue tests were performed for two type lead-free solders using horizontal-type electrical servo hydraulic push-pull fatigue testing machine. Materials employed were Sn-3.0Ag-0.5Cu and Sn-5Sb. The results from Sn-3.0Ag-0.5Cu were compared with those obtained using a bulk specimen in a previous study. Relationship between strain range and number of cycles to failure of the small-sized specimen agreed with those of the bulk specimens. The testing techniques are applicable to Sn-5Sb following the Manson-Coffin law. These results confirm that the testing technique proposed here, using small-sized specimen, is suitable to get fruitful fatigue data for lead-free solder compounds.

Abstract: High performances of tool materials and lubricants have been necessarily developed to extend die life for hot forming of steel. To promote the developments, economical and simple evaluation testing methods have been required. Tribological performances of tool materials, surface treatments, and lubricants are examined by this test. In this paper, a tapered-plug penetration test has been devised for hot forming of steel. It was found that the combination of an appropriate non-graphite lubricant and a nitride die was effective in reducing in galling and friction between a die and a work by the tapered-plug penetration test.

Abstract: This paper discusses and compares the current development of the methods and techniques of embedded software testing. A compromised and practical embedded software testing method, which is between intervention and non-intervention, is proposed and the flow process is provided as well. The method has been verified by a real-case experiment and the result is satisfactory. Key words: Embedded software; testing method

Abstract: Expensive special equipments are often employed to evaluate the performance of low voltage battery, because of the loss voltage of test terminal and line. In the present paper, an economic method was proposed to evaluate fuel cell performance using the booster power supply and electronic load with remote sense. The testing method was deduced theoretically and applied to study the performance of the direct methanol fuel cell . According to the results, it was found that the method was economic applicable and feasible.

Abstract: With more and more precise calculation and analysis to the bridge, and its carrying capacity assessment and repair reinforcement universal attention, it is necessary to acquire the influence line of bridge responses corresponding with moving-load position. A method is presented to obtain the influence line by experiment. A laser rangefinder with large range is added to original test instruments. The moving load position parameter can be looked on as displacement after the signal conversion, which can be synchronously collected together with the response signal. The inverse function principle is introduced to process the data. The examples indicate that the present approach can accurately measure the influence line.

Abstract: Satellite solar radiation pressure torque is one of the major long-term interference after the satellite finishes positioning and starts to working. However, there is no method to verify the calculation of solar radiation pressure torque. This paper is to analyze the in-orbit telemetry data of satellite DFH-3. Based on the results of data fitting and pressure torque calculation, the paper aims to test the accuracy of the calculation methods.

Abstract: Flaking and spalling caused by rolling contact fatigue associate with a small crack, and a special testing method and machine are required to study the small fatigue crack behavior under shear mode loading. It was found by authors that the behaviors of small shear-mode fatigue cracks from the inclusions and the artificial defects could be successfully observed by applying the fully-reversed torsion coupled with static axial compressive stress. However, the servo-hydraulic fatigue testing machine is quite expensive for purchase and maintenance, and large installation space is necessary for the hydraulic and cooling systems. Moreover, the presence of axial compression significantly lowers the frequency of torsional loading, which consequently results in low testing speed. In this study, a cost-effective, space-saving and high-speed fatigue testing method was newly proposed, and the shear-mode fatigue crack growth tests were carried out by using the developed machine. Based on the obtained experimental data, the potential of the new testing machine is discussed.

Abstract: Thermal fatigue is a common problem when ceramics are used at high temperature. Typically, the mechanic properties of ceramics decrease after either long service times at high temperatures or cycles of temperature changes. The thermal fatigue process, the factors influencing the thermal fatigue and the prediction of the thermal fatigue life of ceramics are concerned topics. The thermal fatigue of ceramics is mainly explained by the critical stress fracture and thermal shock damage theories. The thermal fatigue tests include the traditional strength method, the quench-indentation method and the non-destructive detection such as the acoustic emission technique. Based on the thermal fatigue theories, the thermal fatigue life can be predicted using built models. The establishment of the standards for the testing of ceramic thermal fatigue will enhance the comparability of experimental data and further promote the development of analysis theory of thermal fatigue, benefiting the design of engineering ceramics.