推 ntust661:機械製造 11/07 23:34
Consdier plane strain compression of a metal block from an intial thickness
of 25 mm to a final thick ness of 20,, the metal has a true stress-strain
curve σ=700*strain^(0.2)
a) determine a lower bound on the work per unit volume required to produce
this shape change
b) If the compression process is completed in 10 milliseconds, estimate an
average value for the strain rate for the process.
It is proposed to use an axi-symmetric drawing operation to reduce the
diameter of a cylindrical rod of steel form D0 to D0/4
a)If the steel behaves like a perfectly-plastic material, and there is no
redundant deformation or friction in the process, then determine the minimum
number of drawing stages to obtain this reduction?
b)If the stress-strain curve in compression was stress=700*(strain^(0.2))Mpa
,estimate an approximate value for the uniaxial yield stress of the drawn
rod with diameter D0/4
A perfectly-plastic piece of steel rod(yield stress = 700 Mpa) of diameter 50
mm is extruded down to a diameter of 25mm in a single stage operation using a
die of apical angle 2×α=30°. The rod enters the die with a speed of
100 mm/sec. The power cosumed in the extrusion process is 300kw. Estimate
the extrusion pressure and process efficiency.
第一題那個如果是ideal process的話是不是直接用 strain=2*ln(25/20)
wi=(700*10^6*(0.4463)^1.2)/1.2
strain rate 是第一次看到 strain 的改變率嗎？
所以是(0.02-0.025)/(0.025*10)嗎？
第二題感覺要假設的變數不少
拜託各位大大，仿間的書我也有翻一下但解述的方向不太一樣，對於這些題目
我不確定要找哪類型的書
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