A Framework for Designer-Driven Exploration of Computational Weld Mechanics Design Space

2011 ◽  
Author(s):  
Mahyar Asadi ◽  
John A. Goldak
Keyword(s):  
Thermal Stress ◽  
Design Space ◽  
Continuous Optimization ◽  
Displacement Function ◽  
Welded Structures ◽  
Cpu Time ◽  
Welded Structure ◽  
Isolated Points ◽  
Set Up ◽  
Transient Thermal

This paper demonstrates a framework for analyzing multiple analyses of welds and welded structures as a single run. For each point in the design space a 3D transient thermal-stress analyses is solved for the weld and/or a welded structure. This enables the designer to explore the design state space for the design points specified in a Design of Experiments (DOE) matrix. This makes it simpler and quicker for a human to set up tens or hundreds of analyses. Also the CPU time to solve each analysis must be sufficiently short. Examples of DOE matrices created for Computational Weld Mechanics (CWM) optimization analyses are presented; i) a discontinuous combinatorial optimization of the weld sequence to minimize distortion in a girth weld, ii) a continuous optimization to mitigate distortion of an edge welded bar using side heaters, pre-bending with prescribed deflections at isolated points and pre-bending with a smooth prescribed displacement function.

Can a Weld in Welded Structure Be Made With Zero Residual Stress?

2015 ◽  
Author(s):  
Stanislav Tchernov ◽  
John A. Goldak
Keyword(s):  
Residual Stress ◽  
Optimization Problem ◽  
Design Space ◽  
Design Parameters ◽  
Cpu Time ◽  
Welded Structure ◽  
Transverse Distance ◽  
Heated Area ◽  
Open Question ◽  
Heater Design

While solving a sequence of seventeen optimization projects to predict the values of the side heater parameters that would be expected to minimize camber distortion in an edge welded bar, the design parameters that reduced distortion to effectively zero were not unique. This raised the question if any of the designs that minimized the distortion effectively to zero also minimized the residual stress. To answer this question three different measures of residual stress were evaluated for all 1451 designs. The Computational Weld Mechanics (CWM) optimization problem is to find the best point in the 4D space of side heater design parameters: flux, heated area, longitudinal and transverse distance from the weld such that the final residual stress is as low as possible (minimized). To evaluate the objective function for each point in the 4D design space, the associated 3D transient non-linear thermal visco-elastic-plastic stress analyzes was solved. A FEM mesh with 6600 8-node brick elements and 9438 nodes was solved for 166 time steps in 10 minutes of single-core CPU time. In the seventeen optimization projects, 1451 weld analyses were solved in 75 quad-core CPU hours by one person in two calendar weeks. The residual stress was effectively reduced to zero in some designs. These designs also reduced distortion to effectively zero. Whether a design that effectively reduces the residual stress to zero is unique remains an open question.

scholarly journals Comparison of Thermal Stress during Short-Circuit in Different Types of 1.2 kV SiC Transistors Based on Experiments and Simulations

2017 ◽  
Vol 897 ◽  
pp. 595-598
Author(s):  
Diane Perle Sadik ◽  
Jang Kwon Lim ◽  
Juan Colmenares ◽  
Mietek Bakowski ◽  
Hans Peter Nee
Keyword(s):  
Thermal Stress ◽  
Short Circuit ◽  
Thermal Simulation ◽  
Temperature Evolution ◽  
Power Devices ◽  
Different Types ◽  
Transient Thermal

The temperature evolution during a short-circuit in the die of three different Silicon Carbide1200-V power devices is presented. A transient thermal simulation was performed based on the reconstructedstructure of commercially available devices. The location of the hottest point in the device iscompared. Finally, the analysis supports the necessity to turn off short-circuit events rapidly in orderto protect the device after a fault.

SPH Analysis for Transient Thermal Stress of FGMs with Temperature-Dependent Properties

2015 ◽  
Vol 1096 ◽  
pp. 297-301
Author(s):  
Gui Ming Rong ◽  
Hiroyuki Kisu
Keyword(s):  
Thermal Stress ◽  
Thermal Conditions ◽  
Functionally Graded ◽  
Temperature Dependent ◽  
Graded Materials ◽  
Initial Stage ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Temperature Dependent Properties ◽  
Transient Thermal

A formulation using the deviatoric stress and the continuity equation is extended to the analysis of the dynamic response of functionally graded materials (FGMs) subjected to a thermal shock by smoothed particle hydrodynamics (SPH), in which temperature dependent properties of materials are considered. Several dynamic thermal stress problems are analyzed to investigate the fluctuation of thermal stress at the initial stage under three types of thermal conditions, with the addition of two kinds of mechanical boundary conditions.

scholarly journals OS0802 Analysis of a Smart Multilayer Composite Disk for Control of Transient Thermal Stress

2013 ◽  
Vol 2013 (0) ◽  
pp. _OS0802-1_-_OS0802-2_
Author(s):  
Fumihiro ASHIDA ◽  
Sei-ichiro SAKATA ◽  
Takuya MORIMOTO ◽  
Tsuyoshi YAMADA
Keyword(s):  
Thermal Stress ◽  
Multilayer Composite ◽  
Transient Thermal Stress ◽  
Transient Thermal ◽  
Composite Disk
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