大阪大学 · 工学
王一迅教授の研究室では、溶接構造物の疲労寿命と破壊挙動を高精度に予測するための、溶接部の応力集中係数（SCF）の高精度な評価手法を開発しています。特に、実際の溶接形状をより正確に再現するスプラインモデルを用いたパラメトリック式の構築や、数値解析（FEM）と実験（DIC、XRD）を融合した局所ひずみ・平均応力の影響評価が特徴です。また、溶接不能とされる高リン鋼の接合技術（線形摩擦 welded など）の開発や、疲労修復技術の最適化についても実践的で応用指向の研究を進めています。
Figures are computed from collected data and may differ slightly.
The existing parametric formulae to calculate the notch stress concentration factor of fillet welds often result in reduced accuracy due to an oversimplification of the real weld geometry. The present work proposes a parametric formula for the evaluation of the notch SCF based on the spline weld model that offers a better approximation of the real shape of the fillet weld. The spline model was adopted in FE analyses on T-shape joints and cruciform joints models, under different loading condition
Abstract Weathering steel with high phosphorus content usually cannot be joined by fusion welding due to the possible solidification crack. The present study successfully joined the unweldable weathering steel SPA‐H by linear friction welding (LFW) above the A 3 temperature. The microstructure, microhardness, and residual stress were measured and analyzed. The stress concentration factor (SCF) of LFW joints was assessed by the finite element method (FEM). The influence of flash on the fatigue st
The existing <i>S-N</i> curves by effective notch stress to assess the fatigue life of gusset welded joints can result in reduced accuracy due to the oversimplification of bead geometries. The present work proposes the parametric formulae of stress concentration factor (SCF) for as-welded gusset joints based on the spline model, by which the effective notch stress can be accurately calculated for fatigue resistance assessment. The spline model is also modified to make it applicable to the additi
Experiments and FE analysis were conducted on the fatigue repairing techniques of deck -to-vertical stiffener weld in the steel bridge deck. The steel bridge deck was modeled to analyze cracking reason of deck -to-vertical stiffener weld. The fatigue repairing experiment was carried out on three repairing techniques. The fatigue life and stress distribution of the deck-to-vertical stiffener weld were analyzed and repairing effects were compared. Repairing craftsmanship with different parameters
The existing methods of assessing the fatigue life of welded joints fail to consider local strain ranges and mean stress at the weld toe. The present work proposes a novel approach to assessing the fatigue life of welded joints by conducting measurements with digital image correlation (DIC) and X-ray diffraction (XRD) in combination. Local strain ranges at the weld toe of gusset welded joints were measured by DIC. Hammer peening was conducted on the welded joints to introduce different initial s
The mild steel with low phosphorus is vulnerable to corrosion while higher phosphorus often results in hot crack by fusion welding. The present study evaluated microstructures and mechanical properties of high phosphorus steels joined by friction stir welding below the A 1 temperature. The microstructure was analysed considering various phosphorus contents, and mechanical properties were assessed by digital image correlation. The results suggest that alloying elements (nickel, chromium and niobi
Cold spray is a solid-state additive manufacturing technology and has significant potential in component fabrication and structural repair. However, the unfavourable strength–ductility synergy in cold spray due to the high work hardening, porosity and insufficient bonding strength makes it an obstacle for real application. In recent years, several methods have been proposed to improve the quality of the cold-sprayed deposits, and to achieve a balance between strength and ductility. According to
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