Modeling the effect of microstructures on thermal stress for virtual prototyping of TWTA samples

Abstract

Abstract This study presents a thermal stress FEM model of five different Traveling Wave Tube Amplifier components subjected to a 300K–823K continuous heating/cooling cycle. The effects of variation in the constitutive composite brazed material properties, complex shape structure, and artificially introduced microstructure parameters (pore shape, size, and location) are analyzed. Von Misses Stress is used as a decisive parameter. Complexity in shape, pore location, and porosity are shown to affect thermal endurance. Microstructures with sharp edges concentrate more stress than spherical or edgeless microstructures and thus lower thermal performance. The presence of microstructures near the interface edge (near-ceramic) induces greater thermal stress than near the filler location. The results depict that an optimal porosity value exists, which minimizes thermal stress. An empirical linear relation indicates that the braze material property and shape factor are the dominant parameters. This study can be useful to the aerospace industry for the virtual prototyping of TWTA.