Question

350 350 300 300 Same plot, but with expanded x axis 250 250 200 200 Stress (MPa) Stress (MPa) 150 9150 100 ū100 50 50 0 0 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01 Strain Strain

1-Determine the % elongation, yield stress and ultimate tensile strength of the material tested above

2-Calculate the elastic modulus of the material tested above

3-If a 200mm cylindrical rod of the material tested above, with radius 20mm, was subjected to a tensile load of 200kN, what would the length be?

4-An underground wastewater steel pipe with 2mm walls carries an ammonia solution of 40 g/m³. The pipe is in contact with groundwater (assume 0 g/m³ ammonia). Determine the diffusion rate of ammonia through the pipe at 27⁰C. D₀ = 8 x 10^-6 m²/s, Q_d = 0.7eV Assume the system is at steady state.

5-An aluminium alloy is to be used as a structural member and the Architect has specified a maximum applied stress of 200 MPa. The fracture toughness of the alloy is 47 MPa m^1/2. Determine the maximum external crack length which can be permitted during the manufacturing process. Assume Y = 1

6-For an applied stress of 200MPa, calculate the stress at the tip of a surface crack of length 0.7mm with tip radius 1.9 x 10^-2 mm.

Answer 1

350 350 UTS 300 300 Same plot, but with expanded x axis 250 250 200 200 YS Stress (MPa) Stress (MPa) 150 $150 100 # 100 Fracture point 50 50 0 0 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01 Strain Strain

expressed as OL Di) Percentage elongation is the strain at fracture in tension, percentage At fracture point, from the graph strain = 0.16 :- percentage elongation - 44 7100 = 167 12 yield strength is the maximum stress in elastic C/ linear] region. From the graph. Coenoted by ys), it is equal to, Ys=225 mpa the iii) Ultimate tensile strength corres ponds to the maximum stress in the material can with stand cit is denoted by Uts in the graph. ܝ ܙ UTS = 330 MPa 22 Elastic modulus corresponds to the slope of in the initial linear region of the stress- Castrainer graph CS Scanned with

4 Ammonia water -ox a C2 concentration gradient, de C2-C, Co-40)9/m3 da д 2 mm -3 ΑΟΧιο Kg/m 3 2x103 m = - 40 z Kg/mA -20 kg/mt ... According to Fick's first law the diffusion flux, of diffusion, J -D dc doc where D is the diffusion coefficient, Da Do e Qe KT KC Boltzman constant ) = CS Scanned with C Cañisc81617x10 Seya Cü electron volts per Kelvin)

ef T= 27°C 300K 1.39x10" MIS 0.7 ev : Da 8x10x 8.617x15 eyk x 300K : De 8x1oºx exp G 5°x exp(-0.7ev 8:617x1Ō ser x300K Do=8x10 m/s K -17 J = -17 -1.39 X10 xca 17ml - 20 Kg/m 4 ར CS Scalined with 78 XIÓ Rith 78 xlo 16 kg m 35) CamScanner