Ductile failure is characterised by: Select one or more: □ a. Significant elongation to failure A smooth fracture surface □ c. Minimal reduction in cross sectional area Od. The component breaking into many pieces O e. Cavity Coalescence b.

Brittle failure is characterised by: Select one: O a. Little or no elongation to failure O b. O C. O d. O e. Cavity coalescence A significant reduction in cross sectional area Dimples in the fracture surface The component breaking into few pieces

MECH.ENG. DESIGN 1

39)A tensile test specimen has a gage length=3.0 inches and a diameter=  .75 inches. Yielding occurs at a load of 38000lbs. The corresponding gage length=3.0103 inches (neglect the .0.2% yield point). The maximum load of 54000lbs is reached at a gage length =3.453 inches. If fracture occurs at a gage length of 3.873inches, determine the percent elongation at fracture (Round to the nearest whole %)

A tension test was conducted for a cylindrical specimen of stain-less steel having an initial diameter (D) of 10.85 mm. Calculate the percentage reduction in area if the fracture diameter of the specimen (d) is 6.15 mm. Select one: O a. 68.87% O b. 69.87% c. 66.87% O d. 67.87%

Q1. (i) Initial strain Please enter your supplied question data Q1. (ii) Eo B (hr¹Pa-¹) n IVICUITO Fracture 0.003 Please enter your answers here Your Q1. (i) Answers: 4.60E-34 Q1. (ii) 3.2 Q2. o (Pa) σo (Pa) 780,000,000 Q3. t (hr) Q2. A component is made from a metal that is known to be viscoelastic and behaves according to a secondary creep rate equation with constants of B and n provided as your input values. If the component is subjected to a constant force that results in the initial strain of E provided to you, determine the design stress for a secondary creep life of 1,000 hrs before attaining a limiting strain, &, of 0.01. Q3. If the same component is subjected to a constant displacement that results in the value of initial stress, o, provided to you, calculate the time for the stress to reduce to 200MPa. Young's modulus of the bolt is E = 200GPa.

A structural component in the form of a wide plate is to be made of a steel alloy that has a fracture toughness of 77 MPa.m ¹/2 and a yield stress of 1400 MPa. Inspection of the plate has identified an internal through the thickness crack of length 7.7 mm. Assume a value of Y=1. What is the maximum stress the component should be subjected to in order to not undergo rapid fracture.

(a) A large medium carbon steel crane hook is thought to contain penny- shaped internal cracks. If the non-destructive test equipment used on the hook is not capable of detecting cracks smaller than 20 mm diameter, determine the fracture toughness required from this steel if the safety factor on stress is to be 2. The yield stress of the AISI 1045 grade steel is 1050 MNm². Note: For this crack geometry, the 'compliance function' Y in the Stress Intensity Factor (K)) may be taken as 1. (b) A surface crack of 2.5 mm depth and a certain length is found in a thick rectangularcomponent. The component is schedule to be repaired in 6 months. The component is subjected to zero to maximum stress of 340 MPa, 50 times per hour. It was known that for this component catastrophic failure occurs when the crack size reaches 12 mm in depth. Assuming that the crack geometrical shape (aspect ratio) remains constant during crack growth, will the component fail before repair? For the crack geometry, the…

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If a large component is subjected to a cyclic loading under o = 300 MPa and fracture toughness (KIc=60 MNm-32). The material behaves according to Paris Law., it was inspected using ultrasonic techniques, from which the largest surface crack was found as 5mm in length a constant loading frequency of 0.02 Hz. the Paris Law constants are A=1.5x1012 (m/M MNM3/2) m per cycle, and m=3. Take Y=1.12 A) Calculate the number of cycles to failure. B) Determine the time it takes for rupture. C) Discuss the effect of fracture toughness Klc if its value reduced to be 30 MN m-3/2 D) Discuss the main parameters Effect the Fatigue life.