| Summary: | 碩士 === 國立中央大學 === 機械工程研究所 === 81 === The major objective of present paper was to investigate the
deformation of the sheet metal during a shearing process using
the finite element techinque. We investigated the inflenuce of
material properties and punch and die clearence on the maximun
punch force. In shearing process, the state of the workpiece
is from elasticity to plasticity ,and then to fracture. We
created a model of elasticity--plasticity, and introduced the
concept of forming limits to determine the crack-initiation.We
used a finite element program MARC to set up a 3D model and to
slove the state of workpiece.From the postdata of MENTAT, we
can plot the deformation ,strain and stress of a shearing
process by a contour plot. This helps us to know the state of
workpiece very clearly in shearing process. Analyzing results
show that total punch force does not vary with the clearance
when working piece thickness remains constant. Furthermore,
friction durning the shearing processes also was considered.
However, no evidence showed that friction is a dominant factor.
The thinkness of workpiece and the yiled stress influence the
maximun punch force.
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