The new experimental "restraint joint" method has been proposed by the authors in order to obtain a welding joint with both ends of base plate fixed rigid.
In this experimental method, the distance between the two fixed ends, which may be called " restrained distance " must always be maintained constant.
For this purpose the joint test plates bound by Mohr's tension tester are set up as illustrated in Figs. 1 and 2.
And the external load by the testing machine must be regulated through quick action so that the restraint distance may be kept constant.
During the experiment carried not by the authors the welding reaction stress in weld metal under restraint varied with welding progress as shown in Fig. 5.
In the figure, the final stress at each pass may be regarded. as a kind of yield stress or plastic flow stress in weld and it is considered that each final stress should be a maximnm stress at each pass.
Extending this principle to many kinds of restraint joint in practice, the interesting results on actual welded construction have been obtained.
The authors have examined and measured the reaction stress caused by erection butt weld on the seqeral ships which were built at Yokoyama Shipyard in recent years.
Comparing thus obtained results with the above experimental results In " restraint joint ", it is clarified that the degree of restraint in such a heavy welded construction is very small, or such a joint should rather be regarded as so-called free shrinkake joint.
Because mosl welded constructions are movable with welding shrinkage force, the reaction stress existing in a construction should be equivalent to the stress which would be obtained from the static friction force to the construction.
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