Jakobsson, L., McInally, G., Axelson, A., Lindman, M. et al., "Severe Frontal Collisions with Partial Overlap - Two Decades of Car Safety Development," SAE Technical Paper 2013-01-0759, 2013, doi:10.4271/2013-01-0759.
Frontal Severe Partial Overlap Collisions (SPOC) also called small overlap crashes pose special challenges with respect to structural design as well as occupant protection. In the early 1990s, the SPOC test method was developed addressing 20-40% overlap against a fixed rigid barrier with initial velocities up to 65 km/h. The knowledge gained has been used in the design of Volvo vehicles since then.Important design principles include front side members orientated along the wheel envelopes together with a strong support structure utilizing a space frame principle with beams loaded mainly in tension and compression. This novel setup was first introduced in the 850-model in 1991 and has been refined and patented (2001) in later Volvo front structures.Among the design principles are multiple front side members on each side, helping energy absorption efficiency and robustness. The upper side members absorb energy and also transfer the forces via the A-pillars into the roof and the reinforced body and door structures. The lower side members are connected by a cross member with balanced design combining strength and energy absorption using truss principles. The overall design is made to address loads in multiple directions as well as mitigate front wheel intrusion into the passenger compartment.Real world data, complemented with laboratory testing, show that the improvements have substantial effect on occupant protection, reducing overall injuries over the years and reducing footwell intrusion related injuries specifically.