舶用ディーゼル機関用チェーンの安全性評価法に関する一考案 [in Japanese] A Consideration for the Security Evaluation Method of the chain in the Marine Diesel Engines [in Japanese]
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The chains for the 2nd order moment compensator in the marine diesel engines are designed usually to have extremly large safty margin. However, in a certain ship with the relatively large counter weight to reduce the hull vibration, it is possible to occur the non-linear vibration of the chain by the two node torsional vibration of the crank shaft.<BR>For this problem, the non-linear vibration analysis of the chain was carried out with the measured spring characteristics by means of the chain tightener mechanism, which was represented by the form of T<I><SUB>q</SUB></I>=k<SUB>1</SUB>⋅θ+k<SUB>3</SUB>⋅θ<SUP>3</SUP>.<BR>In order to avoid such a non-linear vibration of the chain, it is important to increase the socalled ith order critical speed n<I><SUB>c</SUB></I>= (60/2π) √k<SUB>1</SUB>/I/i of the chain, which is related to the linear part of the chain spring characteristic k<SUB>1</SUB>, comparing with the rated engine speed n<I><SUB>MCR</SUB></I>. This can be obtained by increasing k<SUB>1</SUB> or decreasing the moment of inertia I of the counter weight. Also, the increase of k<SUB>1</SUB> is able to be realized by increase of the initial chain tension F<SUB>0</SUB> or by stepping up the size of the chain and etc.<BR>From this point of view, in this paper, a security evaluation method for the chain was considered in relation to the value of n<I><SUB>c</SUB></I>/n<I><SUB>MCR</SUB></I>, on the basis of the reaults of the non-linear vibration analysis of the chain.
- Marine Engineering
Marine Engineering 31(9), 661-669, 1996-09-01
The Japan Institute of Marine Engineering