• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.11
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• pp.1-6
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• 2005

In this research, the thermomechanical responses of shape memory alloy(SMA) actuators and their applications in the structures combining strip SMA actuators are investigated. The numerical algorithm of the 3-D SMA thermomechanical constitutive equations based on Lagoudas model is developed using user material(UMAT) subroutine written by FORTRAN. For the numerical results, the ABAQUS finite element program has been utilized with UMAT subroutine of the numerical algorithm of SMAs. The interactions between the host structure and SMA strip actuator are numerically investigated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.12
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• pp.33-38
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• 2005

The large deformation of inflatable membrane structure is numerically and experimentally considered in this paper. The numerical algorithm of wrinkling based on Miller and Hedgepeth membrane theory is developed using user material(UMAT) subroutine written by FORTRAN. Wrinkled area and deformed shapes of inflatable membrane structures are investigated by using ABAQUS with UMAT subroutine of wrinkling algorithm.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.12
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• pp.1153-1160
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• 2008

In this paper, the algorithm of Abaqus UMAT is introduced to analyze the shape memory alloy. The SMA has two main effects which show non-linearity. Due to this, it is hard to analyze SMA using analysis tools and to describe all of two effects. Therefore, in this study, the program using Abaqus UMAT based on Modified Brinson model is used to analyze SMA. The martensite fraction, the most important factor which defines SMA motion, is also calculated by Fortran program in UMAT. In addition, the tensile test of SMA specimen is conducted. The availability of algorithm is proved by comparing analysis to experimental result.

• Structural Engineering and Mechanics
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• v.85 no.5
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• pp.593-605
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• 2023

This work presents a comparison between analytical and finite element analysis for bending of porous sandwich functionally graded material (FGM) plates. The plate is rectangular and simply supported under static sinusoidal loading. Material properties of FGM are assumed to vary continuously across the face sheets thickness according to a power-law function in terms of the volume fractions of the constituents while the core is homogeneous. Four types of porosity are considered. A refined higher-order shear with normal deformation theory is used. The number of unknowns in this theory is five, as against six or more in other shear and normal deformation theories. This theory assumes the nonlinear variation of transverse shear stresses and satisfies its nullity in the top and bottom surfaces of the plate without the use of a shear correction factor. The governing equations of equilibrium are derived from the virtual work principle. The Navier approach is used to solve equilibrium equations. The constitutive law of the porous FGM sandwich plate is implemented for a 3D finite element through a subroutine in FORTRAN (UMAT) in Abaqus software. Results show good agreement between the finite element model and the analytical method for some results, but the analytical method keeps giving symmetric results even with the thickness stretching effect and load applied to the top surface of the sandwich.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.1
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• pp.66-73
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• 2010

This work was focused on the material parameter extraction for the isothermal cyclic deformation analysis for which Chaboche(Combined Nonlinear Isotropic and Kinematic Hardening) and Overlay(Multi Linear Hardening) models are normally used. In this study all the parameters were driven especially based on Overlay theories. A simple method is suggested to find out best material parameters for the cyclic deformation analysis prior to the isothermal LCF(Low Cycle Fatigue) analysis. The parameter extraction was done using 400 series stainless steel data which were published in the reference papers. For simple and quick review of the parameters extracted by suggested method, 1D FORTRAN program was developed, and this program could reduce the time for checking the material data tremendously. For the application to FE code ABAQUS user subroutine for the material models was developed by means of UMAT(User Material Subroutine), and the stabilized hysteresis loops obtained by the numerical analysis were in good harmony with test results.