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Volume 07 - Powder Metal Technologies and Applications Part 6

Tham khảo tài liệu 'volume 07 - powder metal technologies and applications part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | bushings bushings Fig. 31 Density distribution along axis of cylindrical bushing FEA predictions versus experimental results This article has examined the general structure of constitutive laws for the compaction of powder compacts and demonstrated how these material models can be used to model the response of real world components to a series of complex die operations. It identified the general structure of the constitutive law and described a number of models that have been proposed in the literature. This field is still evolving and it is evident that there will be significant developments in this area over the next few years as a wider range of experimental studies are conducted providing greater insights into the compaction process. At the current time there is no universally accepted model. Therefore a pragmatic approach and a relatively simple form of empirical model were adopted requiring for the determination of the unknown functions a limited range of experiments. This selection allowed an examination of the compaction of axisymmetric components in detail and a comparison of general features of the component response with practical measurements. Similar procedures could have been adopted for any of the methods described although in general more sophisticated experiments are required in order to determine any unknown function or coefficients particularly if the shape of the yield function is not known or assumed a priori. References cited in this section 2. ABAQUS Standard User s Manual Version 5.7 Vol 1-3 Hibbitt Karlsson Sorensen Inc. Providence RI 1997 3. N. Aravas On the Numerical Integration of a Class of Pressure-Dependent Plasticity Models Int. J. Numer. Meth. Eng. Vol 24 1987 p 1395-1416 4. Y. Kergadallan G. Puente p. Doremus and E. Pavier Compression of an Axisymmetric Part Proc of the Int. Workshop on Modelling of Metal Powder Forming Processes Grenoble France 1997 p 277-285 14. E. Pavier and p. Doremus Mechanical Behavior of a Lubricated Powder