Modern car bumpers (assemblies) typically consist of an outer panel (skin), a buffer layer (energy-absorbing material), a crash beam (crossbeam), and an energy-absorbing box, forming a four-level protection system.
The outer panel is usually made of engineering plastics such as PP (polypropylene), which offers elastic cushioning, lightweight properties, and corrosion resistance. The buffer layer, located inside the outer panel, is often honeycomb foam or other energy-absorbing structures, designed to handle low-speed collisions. The crash beam, made of steel or aluminum alloy, is the core component for withstanding medium- to high-speed impacts. The energy-absorbing box is a collapsible metal component connecting the crash beam to the vehicle's longitudinal beams, absorbing and dispersing impact energy through pre-set folding deformation.
The core considerations for using plastic materials for the outer panel include pedestrian protection, automatic rebound to repair minor scratches, a 60% weight reduction compared to steel, and corrosion resistance in humid environments.
The core function of the bumper system is to absorb and mitigate external impact forces, protect the front and rear of the vehicle and the safety of the occupants, reduce pedestrian injuries in low-speed collisions, and also serve to decorate and beautify the vehicle body and optimize aerodynamics.