Question

I. Two samples A and B weidical for all the properties Sample A has a cross-section free Which of the following is correct for the best result? of the cous-section of sample. The samples are tested to evaluate their desce n der complet o A * C This information is not new to the entrance limit Most possibly, sample A has a higher educe limit Mest possiblyple Aand same lethem e t Moving to another question will this response

Answer 1

1. Given that two samples A & B are identicals for all their properties, but A has a cross-section five times to that of sample B. They are tested for completely reversed axial loading. We need to discuss their endurance limit.

mar Tension - Time 9 = 0 Compression

See, in completely reversed loading mean stress will be zero, but stress amplitude will be there. So, if we assume that the load applied will be the same to both of the samples. Sample A having more cross-section area will experience less stress & hence have a high endurance cycle or it will fail after B fails.

Hence option B is correct

2. We will discuss each option one by one

Option A ) From experiments & previous metalworking practices it has been observed that grey cast iron has very less or no notch sensitivity. Hence this option seems correct.

Option B) Grey cast iron is full of graphites hence, this graphite nodules acts as stress concentration region inside the bulk of gey cast iron, hence while designing the parts made by CGI we must consider this factor. Hence this option also seems correct.

Option C) is not correct.

Option D) See, generally grey cast iron has been used in designing automotive parts such as crankshaft and pressure plate, machine beds, etc.. because of its anti-vibration, machinability, and frictional properties.

Hence seeing its general use, we can say that in the design of grey cast iron surface roughness is not that important.