Abstract
High temperature components such as boiler tube and jet engine turbine blade undergo multiaxial creep damage. Although multiaxial creep testing investigation is required for safety high temperature components designing, there are few commercial testing machines which can conduct multiaxial loading at high temperature. A new miniature cruciform specimen, which has a 5 mm square size plane stress gauge part, was designed by using FE analysis. A biaxial tensile loading creep testing machine was also designed to conduct multiaxial creep testing. The testing machine has 2 kN loading capacity and 1 kW furnace. We had also developed a non-contact displacement measuring method for the miniature specimen. This method uses conventional optical camera to get the surface observation photograph. Chasing the trace of the target mark painted at surface of the specimen, we can get the displacement of the specimen. The calculated strain value obtained from the non-contact displacement measuring method corresponds with the strain gauge value at room temperature. By using the multiaxial creep testing machine and the non-contact observation system, we can investigate not only deformation of the testing specimen but also surface conditions of materials during the creep testing.
Highlights
Structural components such as thermal power plant pipe and turbine blade of airplane engine undergo uniaxial loading and multiaxial loading at high temperature
As testing specimen size miniaturization will enable to conduct mechanical testing with a small amount of materials which is sampled from the actual structural components such as thermal power plant pipe and turbine blade of airplane engine, a miniature cruciform testing specimen and testing machine are required for creep testing
Since there is no commercial miniature multiaxial creep testing machine for cruciform specimen, we have developed a biaxial tensile loading testing machine
Summary
Structural components such as thermal power plant pipe and turbine blade of airplane engine undergo uniaxial loading and multiaxial loading at high temperature. One is a conventional uniaxial tensile loading using a notched bar specimen Another testing method is applying combined tension-torsion loadings to a hollow cylinder specimen [1,2,3]. The other testing method is applying biaxial tensile loadings to a cruciform specimen. As testing specimen size miniaturization will enable to conduct mechanical testing with a small amount of materials which is sampled from the actual structural components such as thermal power plant pipe and turbine blade of airplane engine, a miniature cruciform testing specimen and testing machine are required for creep testing. The strain value obtained from the non-contact displacement measuring method corresponds with the strain gauge value and linear variable differential transformer value at room temperature and high temperature, respectively
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