Transient Thermomechanical Sensitivity Analysis Using a Complex-Variable Finite Element Method and Development of a High-Throughput Tensile Test Protocol for Ti-6Al-4V Additively Manufactured (AM) Components

Date
2022
Authors
Rios, Gerardo Aaron
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Abstract

A complex-variable transient thermomechanical element was developed and used to compute highly accurate sensitivities of the thermal and stress time-dependent responses of a thick-walled cylinder with temperature-dependent material properties with respect to fifteen material, shape, and loading parameters using the complex Taylor series expansion method (CTSE). The analysis was conducted by employing a complex-variable user element within the Abaqus commercial finite element software, herein called ZFEM, using real and imaginary nodal degrees of freedom (DOF). The real coordinates denote the spatial coordinates, as typical, and the imaginary nodal DOF denote the perturbation of the geometry for shape sensitivities. Upon completion, the imaginary DOF hold the partial derivatives of the temperature and the displacements with respect to the parameter of interest. The conclusions show that ZFEM can be utilized to obtain time-dependent sensitivities with high accuracy and precision for transient thermomechanical analyses that are computationally more efficient in comparison to finite difference methods. Next, a high-throughput tensile test protocol was developed for testing metal additively manufactured components. 900 micro tensile specimens were printed using the selective laser melting (SLM) process and can be used to obtain population variance of mechanical properties across the build plate. The test protocol shows that stress-strain curves can be obtained in a fast and efficient manner using custom cavity grips and blob analysis to obtain strain measurement through time with a consolidated MATLAB interface.

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Keywords
Additive manufacturing, Complex-variable finite element method, High-throughput tensile test, Sensitivity analysis, Transient thermomechanical
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Department
Mechanical Engineering