Inflatable Restraint System Design Optimization Approaches

Before numerical design and simulation tools arrived in the automotive industry, occupant restraint systems were devised based on an empirical approach. Optimization through iterative hardware design and prototyping was time consuming. As soon as design and simulation tools like AutoCAD, SOLIDWORKS, CATIA, IDEAS, UNIGRAPHICS, etc. arrived on the market, the average design cycle time reduced drastically. Nowadays, four major approaches can be identified. (1) Companies that can barely afford investments in expensive modeling tools still rely on making hardware prototypes, with limited usage of numerical analysis tools, e.g. on component level for strength analysis. (2) Then there are also companies that prefer to carry out initial validation of baseline models with testing, followed by iterative optimization through CAE models, starting from baseline performance to optimized design, with a validation of the last iteration only as a final check. (3) Some other companies may choose to study each design iteration with hardware prototypes as well as with numerical modeling. This would allow to take manufacturability into consideration at all times, while being able to study typical output unique to modeling like geometrical packaging studies and local stress concentrations inside the model. (4) And lastly, some of the companies design fully through simulation. All four approaches are still employed in the inflatable restraint system design arena. This paper presents cases of the mentioned approaches with corresponding advantages and disadvantages in the described application examples.