Concepts and dimensions of silicon micro-accelermeters are systematically determined for airbag applications.
Design specifications are obtained through the analysis of commercial products and the literature, from which evaluation evaluation criteria are extracted. A double cantilever type accelerometer is selected from the evaluation of nine concept variants by the use-value analysis technique. A piezoresistive type accelerometer is adopted through the comparison of four detection methods, including piezoresistive, piezoelectric, capacitive and optical type. As a damping mechanism, air damping is selected.
For the dimensional design, a design model is proposed and the demensions are determined by optimizing the model. A combined object function of the sensitivity and the lowerst natural frequency is maximized under the constraints on the sensitivity, the frequency, the maximum stress, the maximum displacement and the damping ratio.
Through the finite element analysis of the designed accelerometer, the design model is verified and positions and lengths of the resistors are determined for the maximum sensitivity.
