A hydraulic press is used to produce circular blanks of $$10$$ $$mm$$ diameter from a sheet of $$2$$ $$mm$$ thickness. If the shear strength of the sheet material is $$400$$ $$N/m{m^2},$$ the force required for producing a circular blank is

Consider the following statements related piercing and blanking
$$1.$$ Shear on the punch reduces the maximum cutting force
$$2.$$ Shear increases the capacity of the press needed
$$3.$$ Shear increases the life of the punch
$$4.$$ Total energy needed to make the cut remains unaltered due to provision of shear

Which of the above statements are correct

In sheet metal working, the spring back increase when
$$P:$$ Ratio of bend radius to sheet thickness is small
$$Q:$$ Young's modulus of the sheet is low
$$R:$$ Yield strength of the sheet is high
$$S:$$ Tension is applied during bending

In metal forming operation, the true strain in the $$X$$-direction is $$0.3$$ and in the $$Y$$-direction is $$-0.1.$$ The true strain in the $$Z$$-direction is