Method for optimizing the tolerancing of a set of flexible parts subjected to forces

A method for determining an optimal tolerance interval for producing a first part to be assembled with a second part according to interface surfaces and in compliance with an assembly functional requirement, the parts being represented by their structural digital mockups, the method comprising the steps of:

• acquiring a nominal theoretical position of a plurality of assembly points on the interface surfaces of the digital mockups of the first and second parts;
• acquiring a nominal theoretical position of a plurality of structure points distributed over the interface surfaces of the digital mockups of the first and second parts;
• acquiring, for the pluralities of assembly points and structure points Pi of the digital mockups of the first and second parts, a mechanical restoring stiffness for returning the first and second parts to their initial position in the form of a rigidity matrix [K];
• acquiring a variable of interest, comprising a scalar variable representative of the assembly functional requirement and a cost function defining a value of the variable of interest as a function of the discrepancy of the scalar variable with respect to a nominal of the assembly functional requirement;
• acquiring a set of distortion vectors of the digital mockups of the first and second parts, said distortion vectors being normal to the interfaces surfaces of the digital mockups;
• and
• computing influence coefficients linearly relating each distortion vector to the value of the variable of interest when the digital mockup of the first part, distorted by said each distortion vector, is assembled with the digital mockup of the second part, the assembly of the first and second parts being simulated by placing the assembly points of the two digital mockups in coincidence.