Patent ID: 7328140

Claim:
A method for designing a passenger-side air bag door for an invisible airbag for a passenger-side seat of a vehicle, comprising: determining levels of a noise factor depending on a process condition of laser scoring for forming a tearseam on an inner surface of an instrument panel; determining control factors and levels of each control factor that affect a stress distribution and deformation rate of the tearseam; arranging combinations comprising levels of the control factors according to an experimental design; inputting each noise factor to each combination and measuring a minimum impulse ‘X’ that is able to tear the tearseam of the passenger-side air bag door for operation of the passenger-side airbag, and a maximum impulse ‘Z’ that is unable to tear the tearseam of the passenger-side air bag door in a case of a head or body impact; selecting a level of each control factor based on the measured minimum impulse ‘X’ and the measured maximum impulse ‘Z’; and designing and manufacturing the tearseam of the passenger-side air bag door to tear based on the level of each control factor, wherein selecting the level of each control factor comprises: calculating each signal to noise “S/N” ratio with respect to each combination of the control factors according to the equation: S / N ⁢ ⁢ ratio = ⁢ S / N ⁡ ( X ) + S / N ⁡ ( Z ) = ⁢ 10 ⁢ log ⁢ ⁢ 1 1 n ⁢ ∑ X i 2 + 10 ⁢ log ⁢ ⁢ 1 1 n ⁢ ∑ 1 Z i 2 = ⁢ 10 ⁢ log ⁢ ⁢ 1 1 n 2 ⁡ [ ( ∑ X i 2 ) ⁢ ( ∑ 1 Z i 2 ) ] wherein n: number of noise factors X: Minimum impulse that is able to tear the tearseam for operation of the passenger-side airbag Z: Maximum impulse that is unable to tear the tearseam in the case of a head impact calculating each average of S/N ratios with respect to each level of control factors; and selecting a level of each control factor having a largest average of the S/N ratios.