High-accurate FE simulation on compressive behavior of steel cruciform column with welding imperfection

Due to its various advantages, welding is commonly used in the construction for steel connection. However, the local temperature difference in the welding causes welding deformation and residual stress. The welding deformation and residual stress can significantly impact the load-bearing performance of members. Therefore, it is important to evaluate those behaviors with high precision. In the previous studies, thermal elastic-plastic analysis was used to evaluate welding deformation and residual stress in simulated welded specimens and the compressive simulation was applied to obtain, for example, the load-bearing performance. Nevertheless, there are limitations in assessing structures made up of thin plates. This is because the simulation of welding is typically modeled using solid elements, while the simulation of loading analysis uses shell elements. As a result, these analysis steps are not directly related, leading to deficiencies in the evaluation process. In this study, the solid element model and shell element model were modeled to simulate the welding deformation and residual stress. The corresponding load-bearing capacity results obtained from the continuous loading analysis were compared with the results from experiment to verify the consistency. According to the results, shell models that perform welding analysis simulation followed by continuous compressive analysis are better able to replicate experimental results in terms of out-of-plane deformation and maximum load-carrying capacity under compressive analysis. This is in contrast to solid models, which fall short in reproducing the same results. Moreover, the shell model is also more efficient than the solid model in terms of time saved during analysis and calculation.Cheng Y., Nozawa S., Hirohata M.. High-accurate FE simulation on compressive behavior of steel cruciform column with welding imperfection. Finite Elements in Analysis and Design 221, 103960 (2023); https://doi.org/10.1016/j.finel.2023.103960

Charpy absorbed energy in simulated heat-affected zone of laser-arc hybrid welded joints by high-strength steel for bridge structures

The application of laser-arc hybrid welding (so-called, hybrid welding) to the fabrication of steel bridge members has recently been investigated. One-pass full-penetration butt joints of steels for bridge high-performance structure (SBHS400 and SBHS500) with a thickness of 15 mm were performed by hybrid welding. The sound butt joints by hybrid welding were confirmed by a series of tests. The Charpy impact test was performed on the test pieces extracted from the hybrid welded butt joints with specified test temperatures. A phenomenon known as fracture path deviation (FPD) occurred in most test pieces, due to a large variation in material properties of the heat-affected zone (HAZ), resulting in the difficulty of estimating the toughness of HAZ in hybrid welded joints. Therefore, the Charpy impact test was conducted on the test pieces subjected to the welding thermal cycle tests of hybrid welding, which can exclude the heterogeneity of material properties and obtain the Charpy absorbed energy of the HAZ with high accuracy. The test results indicated that FPD was not observed in all thermal cycle simulated test pieces because the uniform metallographic structures in the vicinity of the notch were formed by the simulated thermal cycle tests, and all thermal cycle simulated test pieces satisfied 47 J at the specified test temperatures, a value that prevents brittle fracture for SBHS. Besides, for investigating the effect of the high Charpy absorbed energy guaranteed by SBHS on the toughness of hybrid welded joints, the Charpy absorbed energy of the thermal cycle simulated test pieces of SBHS and those of conventional steel (SM400B) were compared. The results showed that some of the thermal cycle simulated test pieces of SM400B failed to satisfy 27 J, suggesting that SBHS may ensure a Charpy absorbed energy of 47 J or more in the HAZ of hybrid welded joints.Chen G., Hirohata M., Sakai N., et al. Charpy absorbed energy in simulated heat-affected zone of laser-arc hybrid welded joints by high-strength steel for bridge structures. International Journal of Advanced Manufacturing Technology 127, 2655 (2023); https://doi.org/10.1007/s00170-023-11420-2

A GAN-Augmented Corrosion Prediction Model for Uncoated Steel Plates

The deterioration and damage of aging steel structures have caused huge safety concerns. Corrosion has been identified as a big reason for the deterioration and damage, which causes steel members to lose materials. As a result, the structures’ stiffness and load-bearing capacity will be reduced, which brings economic losses and safety hazards. For the maintenance and repair of steel structures, fast and accurate prediction of corrosion development plays a critical role in numerical simulation analysis, which could save time and costs. In this research, we build a simulation system based on GAN data augmentation with UNet as the generator and MobileNetV2 as the discriminator. The goal is to effectively predict the corrosion behavior of uncoated steel structures over time and under different circumstances. The system can simulate three stages of corrosion based on the dataset collected from experiments. It can also predict the corrosion of steel plates in the next stage. The discriminator of the system can be used to classify the type of steel, the stage of corrosion, and days of corrosion. Based on comparative experiments, our system demonstrates outstanding performance and outperforms the baseline model