The High Accurate Prediction of Welding Distortion Generated by Fillet Welding

Abstract

In order to predict the distortion generated by welding with high accuracy, distortion with fillet welding was measured by three-dimensional photographic measurement. Then, the experiment was simulated by three-dimensional thermal elastic-plastic analysis by FEM. The important matters that should be noted on predicting the distortion with high accuracy were shown by comparing with the results of the experiment and those of the analysis. The results of measuring temperature could be accurately simulated by non-steady state thermal conduction analysis based on FEM. In carrying out the elastic-plastic analysis, four conditions (equilibrium equation, constitutive equation, condition of compatibility and yield condition) should be satisfied. In welding, the temperature largely changed from a melting temperature to a room temperature. So, yield stress of materials largely changed, too. In particular, yield stress becomes about zero above 700℃. The analysis should be carried out under the yield condition that equivalent stress generated in temperature increment ∆T did not exceed yield stress of materials at high temperature above 700℃. It should be sufficiently recognized that the obtained results were not reliable if the yield condition was not satisfied. Angular distortion generated in fillet welding could be accurately predicted by regarding the weld metal as a deposited metal not assuming that a deposited metal zone was a simple triangle. Specifying an influence factor on longitudinal bending distortion was difficult because the absolute value was small. However, it was indicated that the reasonable result could be obtained by regarding the weld metal as a deposited metal because the absolute value of longitudinal bending distortion at pass ② (the second pass) of which restraint was severer became smaller than that at pass ① (the first pass).

Radiosynthesis of 11-[18F]fluoroundecyltriphenylphosphonium (MitoF) as a potential mitochondria-specific positron emission tomography radiotracer

“…Our initial radiosynthetic approach for the preparation of [ 18 F]5 was based on a two‐step synthetic route using 11‐[ 18 F]fluoroundecyl p ‐toluenesulfonate [ 18 F]7 as the prosthetic group (Scheme ). A similar methodology, using shorter‐chain alkyls, has previously been reported for the synthesis of 18 F‐labelled alkyltriphenylphosphonium (alkylTPP) cations 1a and 1b …”

“…Current studies suggest that 18 F‐labelled TPP compounds (Figure ) can be applied as probes for PET to visualise and evaluate mitochondrial membrane potential and thereby assess mitochondrial dysfunction in vivo .…”

Introducing/reproducing of welding distortion and residual stress in analysis for elastic-plastic behaviors of steel plates under compressive loads

“…The self-developed program of which the validity has been verified by comparison with results of several experiments since it was developed (JWS, 2003, KIM et al, 1999, 2003, 2004, 2007a, 2007band 2010.…”

“…Although an actual distribution of residual stress component in welding direction are variously changed by width of plate and welding condition (JWS, 2003;Kim et al, 1999Kim et al, , 2003Kim et al, , 2004Kim et al, , 2007aKim et al, , 2007bKim et al, and 2010, it is neglected. That is, the simply modeled distribution of residual stress component which is largely different from the actual distribution of residual stress component has been generally used.…”

“…To obtain it, a thermal elastic-plastic analysis based on infinitesimal deformation theory, which can predict the WD&RS with high accuracy (JWS, 2003;Kim et al, 1999Kim et al, , 2003Kim et al, , 2004Kim et al, , 2007aKim et al, , 2007bKim et al, and 2010, is carried out on a single-pass butt-welding of thin steel plates. As the next step, the obtained WD&RS is introduced into an elastic-plastic large deformation analysis as initial imperfection.…”