This fundamental research presents an investigation of Wire Arc Additive Manufacturing (WAAM) process on distortion and residual stress using numerical simulation. Further, WAAM geometry was modeled using simplified rectangular bead shape with five layers and three strings. The thermo-mechanical numerical simulation is conducted under consideration of non-linear isotropic hardening modeled by using general purposed FEM software MSC Marc/Mentat. In this simulation, different heat source models (Goldak’s double-ellipsoid and rectangular) are implemented and compared, whereby the later model was to be developed by using subroutine provided in the software. For analyzing the residual stress, separation technique between wall and substrate was introduced after the cooling down period. The outcome of this research is to develop an effective procedure to analyze the distortion and residual stress of wire arc additive manufacturing of stainless steel.

This research presents the numerical evaluation of fatigue crack growth of structural steels S355 and S960 based on Paris’ law parameters (C and m) that are experimentally determined with a single edge notched tension (SENT) specimen using optical and crack gauge measurements on an electromotive resonance machine at constant amplitude load. The sustainable technique is replacing destructive, time-consuming and expensive approaches in structural integrity. The crack propagation is modelled using the 3D finite element method (FEM) with adaptive remeshing of tetrahedral elements along with the crack initiator elements provided in simulation software for crack propagation based on linear elastic fracture mechanics (LEFM). The stress intensity is computed based on the evaluation of energy release rates according to Irwin’s crack closure integral with applied cyclic load of 62.5 MPa, 100 MPa and 150 MPa and stress ratios of R = 0 and 0.1. In order to achieve optimized mesh size towards load cycle and computational time, mesh and re-mesh sensitivity analysis is conducted. The results indicate that the virtual crack closure technique VCCT-based 3D FEM shows acceptable agreement compared to the experimental investigation with the percentage error up to 7.9% for S355 and 12.8% for S960 structural steel.

This paper uses a two-scale material modeling approach to investigate fatigue crack initiation and propagation of the material X10CrMoVNb9-1 (P91) under cyclic loading at room temperature. The Voronoi tessellation method was implemented to generate an artificial microstructure model at the microstructure level, and then, the finite element (FE) method was applied to identify different stress distributions. The stress distributions for multiple artificial microstructures was analyzed by using the physically based Tanaka–Mura model to estimate the number of cycles for crack initiation. Considering the prediction of macro-scale and long-term crack formation, the Paris law was utilized in this research. Experimental work on fatigue life with this material was performed, and good agreement was found with the results obtained in FE modeling. The number of cycles for fatigue crack propagation attains up to a maximum of 40% of the final fatigue lifetime with a typical value of 15% in many cases. This physically based two-scale technique significantly advances fatigue research, particularly in power plants, and paves the way for rapid and low-cost virtual material analysis and fatigue resistance analysis in the context of environmental fatigue applications.

Particle tracking has been used widely to track a single particle motion or trajectory in a medium. One of the applications of the particle tracking is in sports analysis. The tracking method can be divided into, the wearable device based system and the image based system. The wearable device based system utilizing global (GPS) and local (LPM) positioning system to track player movement. The image based system use video image processing to track the player movement and recorded is frames basis. However, the image processing method in a football match requires correction as it is normally recorded from the side of the field. Thus, to solve this problem a set of mathematical solution is needed to convert the image coordinate system (pixels) to the actual coordinate system (meters). The most commonly used is the homography method. The technique requires at least 4 reference points to transform the image coordinate into the actual coordinate system. In this project, a futsal game was recorded. The image coordinate of the player were marked in each frame with respect to the time. The image coordinate data were converted into the actual coordinate using homography matrix. Comparisons were made between the homography technique method and open-source available image warp processing method for validation. Based on the result, the homography coordinate transformation system produce a good agreement with actual player activity on the field.

Variable Analysis for Grain Size Prediction of Austenitic Stainless Steel SS316l Using Heat Treatment

He Railway maintenance industry has been using a welding process to repair the damage on the rail head surface due to its constant and continuous friction with train wheels. The damage area always reoccurs at the same location. A preheating condition has been set in this study to evaluate if it’s an improvement to the rail head surface. As preheating is a process that slow’s the cooling rate of the weld and the base material, resulting in softer weld metal and heat affected zone microstructures with a greater resistance to fabrication hydrogen cracking. The Spectrometer and Hardness test are applied in order to study driven changes in the microstructure and macrostructure of rail specimens at the rail head surface. It is shown that welded layers are clear from any defect due to the normal pressure with rapid change of temperature during usage and also surface oxidation. Welded layer were free from any visible defect such as porosity and crack.