A sheet metal cutting machine cuts the sheet metal via shear force, V as shown in Fig. 1. The crosssection of sheet metal is rectangular with width, b = 3m and thickness, d = 5mm. The sheet metal is
having yield strength σy = 220 MPa; Young’s modules, E = 200 GPa and Poisson’s ratio, ν = 0.3.
Conduct the following analyses at the state of stress when maximum stress reaches σy and before
shearing commences.
a. At the MOST CRITICAL POINT of the sheet metal, calculate the stress state and sketch the
corresponding stress element
b. If SAFETY FACTOR = 2 is considered, what is the MINIMUM shear force, V required to
cut the sheet metal according to following criterions?
i.
ii. |
Tresca criterion?
von Mises criterion? |
c. Sketch the YIELD LOCI for both cases above.
d. As a sheet-metal engineer, which failure criterion in (b) will you use to determine the cutting
shear force? Explain the reason for your answer.
Extracted text: Upper blade (punch) Shear force, V b Sheet metal Sheet metal cutting machine Lower blade (die) Fig. 1