I only see one small issue with your suggestion:

N/m3/2 = (N/m2)(m1/2) = 10-6 MPa m0.5

Note: "mega" equals 106, not 103! The latter is "kilo"...

1 N.m^-3/2 = 1 Pa.m^1/2

So to convert to MPa.m^1/2, divide it by 10^6.

You’re on the right track with your conversion! The Anstis equation provides fracture toughness in units of

N⋅m−1.5

, which can be converted to the standard units of

MPa⋅m0.5

.

To convert from

N⋅m−1.5

to

MPa⋅m0.5

, you can indeed divide by 1000. This is because:

Given that the units of fracture toughness in the Anstis equation are

N⋅m−1.5

, converting to

MPa⋅m0.5

involves recognizing that:

N⋅m−1.5=10−3MPa⋅m0.5

Dear Eduardo Bonome, your conversion factor is wrong. It is not 10-3, but 10-6, as shown in your eq 2 and by Murat Tiryakioḡlu and myself earlier on.