SynopsisIn the previous paper a practical method has been applied for an analysis of nonisothermal crystallization in terms of data of isothermal crystallization. The fundamental equation was written on the assumption of the isokinetic conditions in the following form:where X(t) is the degree of phase transformation at time t, and 7t is the Avrami index determined in the isothermal experiments; K ( T) is connected with the crystallization rate constant of the isothermal crystallization, k(T), through the relation K ( T ) = k(T)"n. The equation is derived on the basis of the well-known theory of phase transformation. Experiments of nonisothermal crystallization of high-density polyethylene were carried out under various cooling conditions. The change in crystallinity during the process was followed by using the above equation in the course of the primary crystallization. A procedure of the analysis of the whole, including both the primary and secondary processes, is suggested as an eminently practical one on a more general assumption.

synopsisThe changes in temperature and crystallinity of polymer during nonisothermal crystallization were theoretically analyzed assuming a cooling condition under which heat transfer occurs at a rate proportional to the difference in temperature between polymer and the,environment. When a plateau appears in the temperature change during crystallization, crystallization temperature can be predicted by a simple method. This method gives nearly the same value as that obtained by successive calculations of temperature and crystallinity throughout the whole process. In addition, a graphic method is presented to predict crystallization temperature. By using the plateau temperature observed in melt-spinning experiments, the crystallization rate under molecular orientation is evaluated. Furthermore, a method applicable to estimating the ultimate crystallinity is proposed. A rough estimation of the increase in the rate of crystallization under molecular orientation was carried out for very high-speed spinning of poly(ethy1ene terephthalate ).

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Purpose -The paper's aim is to investigate the effects of shot peening (SP) on the bending fatigue limit of high-strength steel containing an artificial semi-circular slit. Design/methodology/approach -SP and stress SP (SSP) were conducted on the specimens containing an artificial semi-circular slit with a depth of a ¼ 0.1, 0.2 and 0.3 mm. Then, bending fatigue tests were conducted on the specimens. Findings -The fatigue limit was improved by SP and SSP. In the case of SP and SSP specimens, the specimens with a semi-circular slit under a ¼ 0.2 mm fractured outside the slit, and they had considerably high fatigue limits. Therefore, a semi-circular slit with a depth of under a ¼ 0.2 mm could be rendered harmless by SP or SSP. It was found that the fatigue limit of specimens with a semi-circular slit that received SP or SSP was determined by the threshold condition for non-propagation of fatigue cracks that emanated from outside the slit. Whether the semi-circular slit is rendered harmless or not is decided by the relationship between the stress intensity factor range of semi-circular cracks and the threshold stress intensity factor range. Practical implications -The proposed method can be applied to mechanical parts used in vehicles, aircraft and trains. Originality/value -There are very few examples of evaluations of fatigue limits after SP in materials containing crack-like surface defects. This study calcifies the effect of SP on the fatigue limit having crack-like surface defects.

A new drape elevator is developed to analyze the drape generation mechanism. The drape elevator can measure drape shape, including node generation at various stages during drape formation. The drape elevator method indicates better reproducibility of the drape coefficient of the fabrics than the conventional method. The drape formation process is experimentally found to consist of three stages, seeds generation, their development, and the final stabilizing stages. A new parameter R, evaluating the shape of the drape, is defined in terms of the drape projection. Both the R parameter and the drape coefficient are expected to be useful parameters for the quantitative analysis of fabric drape formation.