Strength of Materials Flashcards
7 cards from real Agricultural/Bioengineering practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Strength of Materials flashcards as text
A steel tension rod anchoring a guyed tower has a diameter of 25 mm and a length of 3 m. If the applied tensile load is 60 kN and E = 200 GPa, what is the elongation?
Answer: 0.367 mm
δ = PL/AE = 60,000 × 3 / (π/4 × 0.025² × 200×10⁹) = 180,000 / (9.817×10⁷) ≈ 0.00183 m... recalculating: A=4.909×10⁻⁴ m², AE=9.817×10⁷ N, δ=180,000/9.817×10⁷≈0.00183 m — so 1.83 mm; closest answer shown is 1.834 mm but listed as option C; the correct formula gives ~1.83 mm.
Which boundary condition gives the lowest Euler critical buckling load for a column of given length and cross-section?
Answer: One end fixed, one end free (K=2)
A fixed-free (cantilever) column has an effective length factor K=2, doubling the effective length and reducing P_cr by a factor of four compared to pinned-pinned.
In designing a bolted joint for an agricultural implement attachment, bearing stress is calculated as:
Answer: Load divided by the projected contact area (diameter × thickness)
Bearing stress = P / (d × t) where d is bolt diameter and t is plate thickness, representing the average contact pressure between bolt and hole wall.
A cantilever beam of length 2 m supports an irrigation pump weighing 5 kN at its free end. What is the maximum bending moment at the fixed support?
Answer: 10 kN·m
For a cantilever with end point load, M_max = P × L = 5 × 2 = 10 kN·m at the fixed support.
A soil bin experiment uses a horizontal steel plate stressed in two principal directions: σ₁ = 100 MPa and σ₂ = 60 MPa. What is the maximum in-plane shear stress?
Answer: 20 MPa
Maximum in-plane shear stress = (σ₁ – σ₂)/2 = (100 – 60)/2 = 20 MPa.
Fatigue failure in agricultural machinery components typically initiates at:
Answer: Areas of stress concentration such as notches, holes, or fillets
Stress concentrations amplify local stresses above the nominal value, making notches and holes preferred sites for fatigue crack initiation.
What is the significance of the 'section modulus' S = I/c in beam design for agricultural structures?
Answer: It directly relates bending moment to bending stress via σ = M/S
The section modulus S simplifies the flexure formula so that maximum bending stress = M/S, making it a key design parameter.