One often finds in the literature semi-empirical failure criteria corresponding to the combination of elementary failure modes with different load components. For example, in [otNCE21], one finds two criteria for the verification of ultimate failure of bolt under combined tensile, shear and bending loads:
(X.D.1) |
(X.D.2) |
The derivation of a reserve factor from expressions (X.D.1) or (X.D.2) is not straightforward. Statring from the definition of reserve factor (value by which loads can be multiplied to reach failure), one verifies that for (X.D.1) it corresponds to the value such that
(X.D.3) |
Similarly, for interaction expression (X.D.2), RF is the solution in of
(X.D.4) |
An analytic expression of the solution of equations (X.D.3) or (X.D.4) as a function of the different parameters is generally not available. Then, one must try other ways to calcula numerically. For the three methods “Interaction_2_SR”, “Interaction_3_SR” and “Interaction_N_SR”, we propose a dichotomic solver. The two first methods are specializations of the general case solved by predefined criterion “Interaction_N_SR”. This corresponds to the resolution in of equation:
(X.D.5) |
The arguments of the “Interaction_N_SR” predefined criterion are parameters in the following order: , , ... and :
(“Interaction_2_SR”, “Interaction_3_SR” criteria need 4 and 6 arguments respectively.) “Interaction_N_SR” predefined criterion returns an Array of two values:
A modified version of the “Interaction_abg_N_SR” predefined criterion corresponds to the resolution in of the following equation:
(X.D.6) |
The arguments of the “Interaction_abg_N_SR” predefined criterion are parameters in the following order: , , , ... and :