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How to put constraint by considering maximum temperature that reaches in engine?

Dear Sunil,

Can you be a little more specific? What property are you looking at? What type of design is it? What is the objective of the optimization?

Guru

Sir, in chapter 11 of Ashby in the 11.1 introduction section the first line of the second paragraph talks of a third material in between the two materials during friction process. this point is not clear sir.

Dear Karan,

In most real life cases, one is interested in friction between lubricated surfaces; and, that is what Ashby et al are indicating in that sentence.

Guru

sir on page 237 in ashby, in plane bearing topic, the first line of the second paragraph tells that when area of contact is large coefficient of friction will also be large, isn't it a contradictionâ€¦.

Dear Karan,

It is contradiction to what? That is not clear to me.

Take a look at Eqn. 11.6 on page 233. The load transmitted is proportional to area of contact and yield strength. In the case of soft materials, area of contact is high ( point contacts can easily flatten and form junctions of larger area); so, load transmitted and hence the dry friction coefficient is high.

Guru

Sir, in the problem sheet 6, first question the thermal diffusivity unit must be area per second but the unit is per degree centigrade, so how to proceed with the problem?

Dear Karan,

I agree; it should be metre^{2} per second; I guess the book mistakenly gives the units of alpha, expansion coefficient for a, the thermal diffusivity.

Guru

Dear Karan,

Why is that? You are given diffusivity; you know how much of distance should the heat be conducted; given these two data, isn't it straightforward to find the time needed?

Guru

Sir,

The unit of Ms is coming out to be Wb/m^2 after solving problem but as per the book, it should come out to be A/m.. plz check that

Dear Aniruddh,

I looked through the formula; I think the expression for the saturation magnetisation given in the book is not correct; I believe there should be no mu0 in the expression.

Guru

sir,

we want to minimize the power loss but by using hybrid cables with core of copper, we are increasing the resistivity twice as coppper cable cable only..which inturn increases the power loss.. Is it minimises the power loss along providing the strength ?