Question

Information for questions 6 to 14: A tensile test on a specimen having an initial diameter of 8.5 mm and an initial gauge length of 45.0 mm, gave the following data: Load, kN Elongation, mm Load, kN Elongation, mm 0 25.42 0.781 2.41 0.0241 27.77 1.563 5.77 0.0577 31.08 3.125 8.66 0.0866 35.49 6.25 11.97 0.1197 39.11 9.375 14.17 0.1417 40.5 12.5 17.11 0.1711 41.22 16 18.95 0.1895 41.73 18.75 21.15 0.2115 42.1 21.875 22.62 0.2262 41.73 25 22.99 0.2299 39.9 28.125 32.55 31.25 Plot the data in stress/strain graph and determine the values in questions 6 to 14. If you think a value cannot be calculated, you should answer, Nor possible to calculate this value Question 6 What is the ultimate strength of the material? Question 7 What is the limit of proportionality for the material? Question 8 What is the proof strength of the material, show this on the graph? Question 9 What is the limit of proportionality, show this on the graph? Question 10 What is the tensile strength of the material? Question 11 What is the nominal stress at fracture for the metal?

specific attention to question 8 (proof strength) the rest i understand. thanks

Answer 1

1)ultimate strength=741.9156N/mm2(maximum value of stress among all)

2)proportionality limit=447.969N/mm2(the value at which deformation is rapid)

3)proof strength=(21.607-24.129)KN(strength at 85% to 95% of proportionality limit)

4)point(0.017356,447.969)

5)Tensile strength=25.42KN

6)stress at fracture=573.6188N/mm2(last point in plot)

---Normally proof strength is the strength at which material gains its original dimension which is 85% to 95% of yield strength.This is used for fastners and bolts cases. so proof strength is experimental value. so I have mentioned it at yield point since it is nearer to it

a

Force(KN)	Elonagation(mm)	Strain	Stress (N/mm2)
0	0	0	0
2.41	0.0241	0.000536	42.4707
5.77	0.0577	0.001282	101.683
8.66	0.0866	0.001924	152.6126
11.97	0.1197	0.00266	210.9437
14.17	0.1417	0.003149	249.7136
17.11	0.1711	0.003802	301.5244
18.95	0.1895	0.004211	333.9501
21.15	0.2115	0.0047	372.7201
22.62	0.2262	0.005027	398.6254
22.99	0.2299	0.005109	405.1458
25.42	0.781	0.017356	447.969
27.77	1.563	0.034733	489.3823
31.08	3.125	0.069444	547.7135
35.49	6.25	0.138889	625.4296
39.11	9.375	0.208333	689.2237
40.5	12.5	0.277778	713.7193
41.22	16	0.355556	726.4076
41.73	18.75	0.416667	735.3952
42.1	21.875	0.486111	741.9156
41.73	25	0.555556	735.3952
39.9	28.125	0.625	703.1457
32.55	31.25	0.694444	573.6188