Strength of Materials Important Questions for JNTU R20 Students
Introduction
Strength of Materials (SOM) is one of the most essential subjects for Mechanical, Civil, and Production Engineering students. It teaches how materials behave under various forces — like tension, compression, bending, and torsion — and why they fail or stay safe.
If you’re preparing for your university exams, GATE, or viva, here’s a complete list of important Strength of Materials questions — arranged unit-wise for easy understanding and quick revision.
Unit 1: Simple Stresses and Strains
Learn how materials deform under different loads and understand the basics of elasticity.
Key Questions:
Define stress, strain, and modulus of elasticity.
Explain Hooke’s law and its limitations.
Describe the stress–strain curve for mild steel.
What is Poisson’s ratio? Explain its significance.
Derive the relationship between the three elastic constants (E, G, and K).
Define resilience, proof resilience, and modulus of resilience.
Explain thermal stresses and give examples.
What are principal stresses and principal planes?
Define factor of safety and working stress.
Differentiate between ductile and brittle materials.
Numerical Focus:
Stress, strain, and elongation in stepped or composite bars.
Problems on thermal stress and strain energy.
Unit 2: Shear Force and Bending Moment
This unit focuses on internal reactions that occur inside beams under various loads.
Key Questions:
Define shear force and bending moment.
Derive the relationship between load, shear force, and bending moment.
Draw SFD and BMD for simply supported and cantilever beams.
What is the point of contraflexure?
Explain sign conventions for S.F. and B.M.
Differentiate between concentrated, uniformly distributed, and varying loads.
Explain the types of beams and support conditions.
What are the conditions for maximum bending moment?
How do you determine the bending moment at any section of a beam?
Numerical Focus:
Drawing SFD and BMD diagrams for different loading types.
Finding maximum bending moment and shear force.
Unit 3: Bending and Shear Stresses in Beams
Learn how bending and shear stresses act within beam cross-sections.
Key Questions:
Derive the bending equation: M/I=f/y=E/R.
Explain the assumptions made in simple bending theory.
Define neutral axis and section modulus.
Derive the shear stress distribution for a rectangular section.
Derive the shear stress distribution for circular and I-sections.
Explain the concept of flexural rigidity.
Define moment of resistance and modulus of rupture.
Differentiate between pure bending and simple bending.
Explain why maximum bending stress occurs at the outermost fibers.
What is the significance of moment of inertia in bending?
Numerical Focus:
Bending stress and shear stress calculations.
Design of beams for strength and stiffness.
Unit 4: Torsion of Circular Shafts
Torsion is an essential topic for understanding shaft design and torque transmission.
Key Questions:
Derive the torsion equation T/J=τ/r=Gθ/L.
What are the assumptions made in the torsion equation?
Define torsional rigidity and polar moment of inertia.
Compare solid and hollow shafts carrying the same torque.
Derive the formula for power transmitted by a shaft.
Explain the concept of the angle of twist.
Define modulus of rigidity and its importance.
Explain why hollow shafts are more efficient than solid ones.
What are the different modes of shaft failure?
Discuss practical applications of torsion in mechanical design.
Numerical Focus:
Torque, angle of twist, and power transmission problems.
Unit 5: Columns and Struts
Understanding column stability is key to preventing structural failures.
Key Questions:
Define slenderness ratio and effective length.
Derive Euler’s formula for buckling load for all end conditions.
Explain limitations of Euler’s theory.
Derive Rankine’s formula and compare it with Euler’s.
What is crippling load?
Differentiate between short, medium, and long columns.
Explain the effect of eccentric loading.
Define strut and compare it with a column.
What is Johnson’s parabolic formula and where is it used?
Explain buckling and crushing failure in columns.
Numerical Focus:
Euler and Rankine column problems.
Eccentric load calculations.
Unit 6: Springs and Thin Cylinders
This unit combines flexibility and pressure vessel design concepts.
Key Questions:
Derive the expression for stress and deflection in a close-coiled helical spring.
Define stiffness and spring index.
Explain proof load and resilience in springs.
Derive formulas for hoop and longitudinal stress in thin cylinders.
What is volumetric strain in a thin-walled pressure vessel?
Differentiate between thick and thin cylinders.
Explain compound cylinders and their construction.
What are the failure modes of thin cylinders?
Discuss practical uses of springs in mechanical systems.
Derive the energy stored in a helical spring under load.
Numerical Focus:
Deflection and stiffness of helical springs.
Hoop stress and diameter change in thin cylinders.
Extra Topics for Viva & Competitive Exams
Differences between elastic and plastic deformation.
Applications of strain energy in mechanical design.
Failure theories — maximum stress, strain, and energy theories.
Importance of moment of inertia in beam and shaft design.
Real-life examples of bending and torsion in machines.
Preparation Tips
Revise all derivations — they are frequently asked in exams.
Practice numerical problems from each topic every day.
Draw clear diagrams for SFD, BMD, and stress distributions.
Memorize important formulas with units.
Relate topics with real-world engineering applications.
Conclusion
Strength of Materials is not just another subject — it’s the backbone of every design, structure, and machine around us. Mastering SOM will give you confidence in designing real-world mechanical systems.
Practice these important Strength of Materials questions, and you’ll be ready to crack both your exams and technical interviews.
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