However, the type of contact body defers. While the plates are defined as deformable bodies, the table is defined as a rigid body. This is done because it is assumed that the table does not undergo any deformation. This not only simplifies the simulation but also save calculation time significantly.
All bodies are assumed to be just touching with each other and no parts are glued. By doing so, deformations are allowed as the parts are allowed to move freely from each contact bodies. Welding path and orientation The weld path is defined using nodes located in the middle of the weldment. The orientation is defined to be perpendicular to the surface of the plates.
The figure below illustrates the weld path and orientation where the weld path is represented by the blue arrow and the weld direction root is represented with the green arrow.
Figure 4: Weld path and orientation. Initial and Boundary Conditions For this simulation, only a thermal initial condition is defined. For the boundary condition, both thermal and structural boundary condition is applied.
To simulate the cooling effects of the environment, a film boundary condition is applied to the surface of the plates. This boundary condition is used to consider the effects of heat loss through radiation and convection. Four point-loads are also applied to the nodes on the plate to represent the clamping force. The location and direction of the force applied is shown in Figure 5 below. The welding parameters are displayed in Table 2 below.
Load case and jobs A load case is created where all loads and boundary condition is applied. The simulation time is defined to be 60 seconds with a constant time step of 0. The total increment of could be increased to achieve a more detailed simulation, however this would drastically increase calculation time. Post-Processing Before the job is submitted to the FEA another subroutine is included to enable the calculation of phase transformation.
However, for this study, the heat source model is based on the works of Zhan et al. The conical heat source is represented by the mathematical model below. Figure 6 below illustrates the conical heat source model. The algorithm is illustrated in the flow chart below. The first argument of the algorithm is to begin calculation only when the peak temperature designated as t 3 in the subroutine, reaches the upper limit, which is degrees Celsius. Then a utility subroutine, elmvar, is the used within the subroutine to extract temperature increments between each increment.
The calculation is only done at the last increment because calculating the Martensite formation at each increment will hugely increase calculation time. The mathematical model is described with the equations below. The cause of such a long calculation time is due to the implementation of subroutines. Observing the result from the post processing file, the difference between each type of heat source can clearly be seen.
Figure 8 below shows the comparison between the three models and a macrograph of a deep penetration laser welding. The number of nodes also determine the amount of calculation the solver has to do. While reducing the number of nodes used could improve wall time, this would reduce the accuracy of the analysis.
A closer gap between nodes is needed, especially near the weld region to obtain a result with reasonable accuracy. The resulting Martensite distibution is illustrated in the figure 10 below. Figure Distribution of Martensite Formation It is observed that the Martensite formation is higher in regions that cool more rapidly.
This shows the correlation between cooling time and the formation of Martensite. Table 4 below shows the percentage of Martensite in selected nodes compared to the calculated value based on the CCT diagram. However, the accuracy of both method is approximate at best. There are several factors that affects the accuracy of calculating the percentage numerically. The first being that the model is used for mild steel with a range of chemical compositions.
This is because, the subroutine uses the temperature history of each nodes. Would you like to become a Hexagon Student Ambassador at your university and benefit from mentoring provided by our engineers? Implement your simulation and communication skills to get an unmatched competitive advantage in the future. Actran is the premier acoustics software to solve acoustics, vibro-acoustics, and aero-acoustics problems. Used by automotive manufacturers and suppliers, aerospace and defense companies, and consumer product manufacturers, Actran helps engineers better understand and improve the acoustics performance of their designs.
Supported Platforms : Windows 7 bit, Windows 10 bit. Adams is the most widely used multibody dynamics and motion analysis software in the world. Adams helps engineers to study the dynamics of moving parts, how loads and forces are distributed throughout mechanical systems, and to improve and optimize the performance of their products.
Use MSC Apex for reasearch or teaching. MSC Apex is ideal for courses covering mechanics of materials, advanced structural analysis or natural frequencies and mode shapes. Get free trial. Skip to main content. Blog Legal Information. Contact person. Wolfgang Krach.
0コメント