Q1. What properties need to be considered for applications calling for following requirements:

  1. Rigidity
  2. Strength for no plastic deformation under static load
  3. Strength to withstand overload without fracture
  4. Wear resistance
  5. Reliability and safety.

Q2. Specific strength of materials is very high when they are in fibre size but lower when they are in bar form – Why?

Q3. Distinguish between creep and fatigue.

Q4. List at least two factors that promote transition from ductile to brittle fracture.

Q5. Which theories of failure are used for (a) ductile materials and (b) brittle materials?

Q6. Explain the difference between the points of inflexion and contraflexure.

Q7.What is difference between proof resilience and modulus of resilience?

Q8. What is difference between column and strut?

Q9.Define buckling factor.

Q10. What is difference between conjugate beam and continuous beam?

Q11.Which factors influence the type of fracture in failure of a material?

Q12.What is Bauschinger effect?

Q13. Explain the rule to find specific heat of aqueous solution.

Q14. What do you understand by equation of state? Write two thermodynamic equations of state.

Q15. According to second law of thermodynamic what is the limitation for conversion of heat to work? What all conclusions are drawn for efficiency of conversion of beat to work?

 

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Eternal learner

Ans 1) (i) Rigidity:- Elastic modulus and yield strength (ii) Strength (for no plastic deformation):- Yield point (iii) Strength (overload):- Toughness and impact resistance (iv) Wear resistance:- Hardness (v) Reliability and Safety:- Endurance limit and yield point Ans 2) Crystal structure has ordered, repeating arrangement of atoms. Fibres are liable to maintain this and thus have high specific strength. As size increases, the condition of ordered and repeating arrangements can't be guaranteed because of several types of defects and dislocations. Thus, the specific strength gets lower. Ans 3) Creep is low and progressive deformation of a material with time under a constant stress at high temperature applications. Fatigue is the reduced tendency of material to offer resistance to applied stress under repeated or fluctuating loading conditions. Ans 4) Manner of loading, and the rate of loading promote transition from ductile to brittle fracture. Ans 5) (a) For ductile materials, we use maximum shear stress theory and maximum distortion energy theory, (b) for brittle materials, we use theory of maximum principal stress and maximum strain. Ans 6) At point of inflexion in a loaded beam the curvature changes and at point of contraflexure in loaded beam the bending moment changes sign. Ans 7) Proof resilience is the maximum strain energy that can be stored in a material without permanent deformation. Modulus of resilience is the maximum strain energy stored in material per unit volume.

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Q12.An increase in tensile yield strength occurs at the expense of compressive yield strength

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