§7.1.4.6: Toughness Conversion (K / J / CTOD → K_mat)

BS 7910:2019 §7.1.4.6 — convert a single toughness test result to K_mat

§7.1.4.6: Toughness Conversion (K / J / CTOD → K_mat)

A small building block that takes one fracture toughness test value — K_{IC}, a J-integral or a CTOD — and converts it to the assessment toughness K_{mat} used by the Clause 7 fracture assessment (Section 7.1.4.6 / 7.3.6). Different labs report toughness in different forms, so this puts them all on the common K_{mat} basis the Clause 7 assessment expects.

The conversion depends on the test form:

• Direct K — only the units are regularized.
• J-integral — converted with K_{mat}=\sqrt{J\,E'} (Eq. 7.15), where E'=E/(1-\nu^2) is the plane-strain modulus.
• CTOD \delta — converted with K_{mat}=\sqrt{m\,\sigma_Y\,\delta\,E'} (Eq. 7.16), where the constraint factor m comes from Eq. 7.17 using the yield and tensile strengths (if these are blank or out of range, m=1.5 is used).

The J and CTOD paths need the elastic modulus E and Poisson ratio \nu; the defaults (205000 MPa, 0.3) are the ferritic-steel values from Table 7.3. The result reports K_{mat} together with the plane-strain modulus E', the constraint factor m used, and the conversion path taken.

Loading the interactive calculator…