ABSTRACT:The phenomenological evolution laws of damage can be defined either based on residual life or residual strength. The failure of a specimen can be defined immediately after or before fracture. The former is called in this paper by "failure defined by approach I" and the latter "failure defined by approach II. " Usually at failure there is a discontinuity of loading variables and, because of this, damage at failure is discontinuous. Therefore the values of damage at failure by two different approaches are not the same. Based on this idea the sequence effects of the phenomenological evolution law of damage given by dD/dN = g(D)f(Φ) were studied. Thin-walled graphite/epoxy tubes consisting of four of [±45] s laminates were used for the experimental study of sequence effects and the effects of mean stress on fatigue life. It was found that the sequence effects in two step uniaxial fatigue for [±45] s graphite/epoxy tubular specimen showed that a high-low block loading sequence was less damaging than a low-high one.

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Under harsh environments in which remote control is impossible, wire-guided control technology is effective for controlling distant underwater vehicles that serve mother ships in missions, such as exploration and installation. When the fiber is unwound from the spool, tension fluctuations occur in the fiber because of the relative velocity of the moving vehicles and unwinding velocity of the fiber. As a result, fiber cables exhibit complicated behaviors, become entangled, and may get cut. In this study, a spool-like design for winding tens of kilometers of fiber cables is proposed by analyzing cable winding. The unwinding performance of the designed spool is estimated by performing nonlinear dynamics analysis of the nonlinear behavior and tension fluctuations observed during the unwinding of the fiber. § 이 논문은 대한기계학회 2 0 0 9 년도 추계학술대회

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