is fracture mechanics fake science?

Nice try, peteranderson6663 @ yahoo . com! ... OK. If the book appears on Google Books, esp. the LIE- and FAKE-mentioning portions of it, I will make sure to have a look at it. And, if the book is priced <= Rs. 1500/- (USD 25/-), I will buy it even with your introduction here alone, Google Books being unnecessary. (Paperback is OK.)

I am not a "real" fracture mechanics engineer, and thus, I sure can (and will!) give it a try, here.

The basic issue (call it difficulty, if you wish) most "outsiders" have with fracture mechanics is the basic nature of this theory---its singularity-involving formulation. Once you get past that part---i.e., once you understand that the real focus of the thoery is not what happens at the singular point but what it tells about the mechanical state of the part and the material's response to it everywhere else---you already are well on your way out of the difficulty.

Now, there are other issues, e.g. the presence of reversibility in the theory despite the irreversible nature of plastic deformation/damage and crack growth, the inability of the theory to integrally include at a fundamental level certain issues like dissipation, size effects, dynamic fracture-effects etc. These issues are there. However, IMHO, these are secondary.

When a freshly minted BS/BE/BTech (Mech./Civil/Biotech) engineer, exuding his new-found confidence in, e.g., Shigley's text and the thick books detailing the standard design practice codes, begins to ask: "How do I design for fracture-related considerations using this theory? You say this KIC is a material property. OK. How does this material property help me in my design procedure? Where, precisely, do I plug it in, in my step-by-step design procedure code for, say, a design-by-strength (let alone design by stiffness/flexibility)?" When he raises those questions, what he is rather indirectly pointing at is this peculiar, singularity-involving nature of the theory. He then thinks that he can circumvent the said difficulty by blowing up the safety factor a comfortable bit more---or by design introducing a smooth circular hole right in the likely path of the growth of a crack (which will reduce the stress concentration). If the solution(s) are as simple as that, why should he bother with the fracture-mechanics theory? Such may be his point of view (also shared by many of his seniors). And, coming from that position, the theory does begin to look FAKE! ... Just a hypothesis.

My two cents.

(And yes, as soon as a low-cost edition comes out, I will go ahead and buy it, even if driven to do so only by plain curiosity and no professional considerations.)

[BTW, are you Dr. Peter Anderson of Ohio State Materials Dept? [URL deleted on request on June 28, 2011]]

Best,

--Ajit

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[E&OE]

or I would say some concepts have been used (or extended) to areas and occasions that these concepts not longer apply.

for instance, if you find a J-integral using plane strain condition, but tried to treat that value as a critical value for sheets of various thickness, you are wrong. another instance, if you find K_ic value for a material and then apply it to simple shear, you are wrong. Experimentalist probably have more to comment. But I have seen these inaccurate (or incorrect, if you would like to say) applications all the time.