Which of the following statements is incorrect? Both the grain boundary and bulk diffusion creep mechanism lead to elongated grains. For linear creep, the creep exponent in the steady-state creep rate equation is around 1. S-N curves are a plot of the stress versus the number of cycles to failure. The relaxation modulus is a time-dependent elastic modulus used for viscoelastic polymers. Crystalline polymers show a large drop in the relaxation modulus around the glass transition temperature.

Creep exercises You are involved in a design for high temperature alloys and have performed a rupture test of material A and B. After data analysis, you noticed that the master curve (o vs LMP) of both material A and B coincide as shown in the diagram below. Based on the rupture strength o (MPa) AtB LMP = T(C+ Int) Which material will you select if they both have same constant (CA= CB)? Which material will you select if C < C? Motivate your answer by means of a calculation.

A 5-mm-thick rectangular alloy bar is subjected to ajtensile load P by pins at A and B, as shown in the figure. The width of the bar is w = 33 mm. Strain gages bonded to the specimen measure the following strains in the longitudinal (x) and transverse (y) directions: €, =710 με and ε,--255 με (a) Determine Poisson's ratio for this specimen. (b) If the measured strains were produced by an axial load of P = 24 kN, what is the modulus of elasticity for this specimen? Answers: (a) v= (b) E= GPa

Consider a cylindrical metal 6 mm in diameter and 50 mm long ispulled in tension. It is known that yield strength and elastic (Young’s) Modulus of thematerial are 200 MPa and 100 GPa, respectively, and its Poisson’s Ratio is 0.3.(a) Determine whether the deformation is elastic or plastic when 6000 N is applied.(b) Calculate specimen elongation (∆l) and reduction in diameter (∆d) when 5000 N isapplied? What are the values ∆l and ∆d when the load is released?(c) If necking occurs at a load of 8850 N, determine the UTS of the metal.(d) Calculate the ductility in terms of % E.L. if the length of the specimen at fracturepoint is 56.0 mm.

A brass wire of diameter d = 2.33 mm is stretched tightly between rigid supports so that the tensile force is T = 93 N (see figure). T The coefficient of thermal expansion for the wire is 19.5 x 106/°c, and the modulus of elasticity is E = 110 GPa. (a) What is the maximum permissible temperature drop (in °C) if the allowable shear stress in the wire is 60 MPa? (Enter the magnitude.) °C (b) At what temperature change (in °C) does the wire go slack? °C

Two triangular wedges are glued together as shown in the figure. The stress acting normal to the interface, o, is MPa. 100 MPa 100 MPa on 45% 100 MPa -100 MPa

The stress concentration occurs whenever there is an abrupt change in the cross-section of a component or there is any discontinuity in the material. The figure given below shows a flat plate with a hole of diameter d. The plate is fixed at one end and the other end is subjected to a tensile load of P = 44 kN due to which there is a change in length of 0.4 mm. The thickness of the plate is 11.5 mm. The maximum stress developed in the flat plate is 228 MPa. Take Young's modulus(E) = 210 GPa and theoretical stress concentration factor =2,   Calculate the following values:  i) Width of the plate (W2) in mm                                                    ( ii) Nominal Stress in MPa                                                                 ( iii) Diameter of the hole (d) in mm

The stress concentration occurs whenever there is an abrupt change in the cross-section of a component or there is any discontinuity in the material. The figure given below shows a flat plate with a hole of diameter d. The plate is fixed at one end and the other end is subjected to a tensile load of P = 41 kN due to which there is a change in length of 0.4 mm. The thickness of the plate is 11 mm. The maximum stress developed in the flat plate is 235 MPa. Take Young's modulus(E) = 210 GPa and theoretical stress concentration factor =2, Calculate the following values: i) Width of the plate (W2) in mm ii) Nominal Stress in MPa iii) Diameter of the hole (d) in mm Hole with stress concentration factor 2 35 mm W2 35 mm P 300 mm 350 mm- 250 mm

Figure Q1(a) shows the stress-strain graphs of four different materials labelled as A, B, C and D. Qualitatively, classified the materials in orderof largest to smallest strain hardening.

A gold-alloy microbeam attached to a silicon wafer behaves like a cantilever beam subjected to a uniform load (see figure). The beam has a length L = 24.5 um and rectangular cross section of a width b = 4.0 pm and thickness t = 0.88 um. The total load on the beam is 14.9 µN. If the deflection at the end of the beam is 1.53 um, what is the modulus of elasticity E, of the gold alloy (in GPa)? (Use the formulas of this example. The beam has constant flexural rigidity EI.) GPa