Viva Questions

Viva Questions : 1. Defin Define e Gaug Gauge e Leng Length. th. Gauge length is the length between which the stress – strain relationship relationship of a material is studied. The distance along the specimen upon which extension calculations are made. The gauge length is sometimes taken as the distance between the grips.

it is the length marked on the parallel portion of a tensile test piece from which the elongation is measured.

2. Differen Differentiate tiate between between ductile ductile and brittle brittle functio functions. ns. In brittle materials, fracture occurs on application of excess stress without deforming the material. In case of ductile stress, the material undergoes permanent deformation before fracture. 3. Define Ultimate Ultimate stress, Yield Stress, Stress, Nominal Nominal breaking stress and and Actual breaking stress. Ultimate stress is that stress which causes the material to just crack. It is the ratio of ultimate load to the area of cross section. Yield stress is the stress at which the material starts yielding. It is the ratio of of yield load to area of cross section. Nominal breaking stress is the ratio of breaking stress to nominal area of cross section. Actual breaking stress is the ratio of breaking stress to necking area of cross section.

4. Why is the the machin machine e named named “UTM” “UTM”? ? Universal Testin Machine (UTM) is used for conducting several tests like torsion tests, tension tests, compression tests, shear tests, etc universally. Hence the name.

5. Define Define the the term term “strai “strain n hardenin hardening”? g”?

 The phenomenon by which crystalline structure of material changes due to yielding thereby increasing its hardness to resist more load is called strain hardening.

6. Explain the terms “range” and “capacity” of the machine. Capacity is the maximum value of input a machine can take. Range is the values that can be taken as input by the machine within its capacity.

a. Close coiled and open

7. Define the terms stiffness, shear stress, modulus of rigidity and proof resilience. Stiffness : It is the property of material by which it resists change in shape when an external load is applied. It is denoted by K. Shear stress : It is the intensity of distribution of force expressed as forces per unit area. Modulus of rigidity : It is the ratio of shear stress to shear strain. It is denoted by G. Proof resilience : It is the maximum strain energy stored in the body.

8. Mention some practical applications of springs. Helical springs are used in gears. Leaf springs are used in automobiles and suspension system.

a. Leaf spring and its uses

b. Is specify 1. Compare the brinell hardness number for ferrous and non-ferrous materials.

2. Give the relation connecting load and diameter of ball indentor for hard and soft materials. 3. equatiom 4. What do you mean by pure Torsion? When there is no bending of the material and is subjected to only torque, it is called pure torsion.

Stree dudrbtiom 5. Define polar moment of Inertia?  The area moment of inertia about all axis perpendicular to the plane of an area is called polar moment of inertia and is denoted by Ip. Ixx and Iyy are the area moment of Inertia about the centroidal xx and yy axis respectively. Ip = Ixx + Iyy 6. Differentiate between single shear and double shear. A lapped joint with two members pulling in opposite directions would result in single shear or both holding together because all the shear force distributed across the bolt cross-section at one location known as single shear with these members in lap slice, the shear force is distribituted across the cross-section of bolt. 7. Define shear area and shear stress.  The area undergoing shear stress is called shear area.  The ratio of shear force to shear area is called shear stress. 8. Derive the equation for Brinell Hardness number. 9. What is leaf spring and mention its applications. Leaf spring is also called Carriage spring. It is a composite spring consisting of several layers of flexible metallic strip joined to act as a simple unit. It is used in heavy applications such as suspension systems.