Question

An aircraft component is fabricated from an aluminum alloy that has a plane strain fracture toughness of 37 MPam. It has been determined that fracture results at a stress of 206 MPa when the maximum (or critical) internal crack length is 2.58 mm. a) Determine the value of Yσπa for this same component and alloy at a stress level of 267 MPa when the maximum internal crack length is 1.29 mm.

Answer 1

Answer:

we are supposed to determine the stress level at which a wing component on an aircraft will fracture for a given toughness of $37 MPa\sqrt{m}$  and maximum internal crack length $1.29 mm$ , given that  fracture

occurs for the same component using the same alloy at one stress level $206 Mpa$ and another internal crack length  (2.58 mm). It first becomes necessary to solve for the parameter Y for the conditions under which fracture occurred , therefore

$Y=\frac{K_{lc} }{sigma\sqrt{\pi a } }$

$=(37Mpa\sqrt{m} )/(206Mpa)\sqrt{\pi \frac{2.58*10^-^3m}{2} } \\=2.82$

$sigma_{c} =K_{lc} /Y\sqrt{\pi a }$

$=(37MPa\sqrt{m} )/(2.82)\sqrt{\pi \frac{1.29*10^-^3}{2} } \\= 293 MPa$