New Chevrolet Sonic designed to be amongst safest vehicles in small car segment
- Designed to meet 5-star Euro NCAP requirements
- Outstanding roof crush performance in the event of rollover
- More than 60% of structure made from advanced high-strength steels
- Front and side airbags for front occupants
- Pedal release system
- Complies with European pedestrian protection requirements
The inherently strong body-frame-integral (BFI) structure of the Sonic combines with an impressive array of active and passive safety features to ensure that the Sonic ranks amongst the best-in-class when it comes to overall vehicle safety.
Occupant safety was an overriding engineering objective for the new Sonic with a no compromise target of a 5-star NCAP safety rating. The highest ratings from the Insurance Institute for Highway Safety in North America were also targeted together with that organisation’s rating as a Top Safety Pick. Roll over safety is ensured by the Sonic’s capability to withstand 4,2 times its own weight in the event of a rollover, a performance that well exceeds roof-crush performance standards.
The basic integrity of the vehicle structure is supplemented by an array of active and passive safety features including ABS anti-lock brakes with Electronic Brake Force Distribution (EBD), and driver and passenger airbag protection, including side airbags. A pedal release system offers added protection for the driver’s lower leg area. In the event of a severe frontal impact is designed to collapse away from the driver’s feet and legs to prevent them form being trapped between the pedals and the vehicle body.
Pedestrian safety was also a design consideration. The frontal area of the Sonic is designed to provide reduced exposure to pedestrian injuries caused by secondary impact with hard under bonnet objects like the battery or engine.
Crash protection designed in
Effective crash impact energy management has been designed into the new Chevrolet Sonic starting with front and rear crumple zones that manage and absorb the initial impact energy in the event of a collision to help maintain the integrity of the passenger compartment.
The front crush zone is made up of the engine compartment side rails and the front bumper system together with the engine sub-frame. These elements are designed to take the brunt of the impact energy in a frontal collision. The engine compartment side rails are made of high-strength steel and will absorb energy whilst maintaining a high load capability as they collapse.
The hydro-formed engine sub-frame has four mounting points and is designed to progressively deform as it absorbs impact energy whilst retaining a high load bearing capability. This ultra-high-strength structure assists in redirecting impact energy as it deforms and is a key component in meeting the rigorous Euro NCAP 5-star standards.
The next line of defence in the event of a front impact is a transition zone that consists of the A-pillars and the instrument panel beam. This structure is designed to distribute energy around the passenger cell.
The floor pan, rocker panels, centre tunnel, A- and B- pillars, and front mid-rails form a safety cage that supports the frontal crush zone and directs energy away from the passenger area.
At the rear of the Sonic the focus is on providing protection for the fuel tank and its connections to avoid ruptures and spillage in the event of a rear end collision. Like the front of the vehicle, the rear end incorporates a crush zone designed to absorb impact energy.
Additional protection is provided by the strong rear suspension cross member. This element of the vehicle assists in directing impact energy through to the side rocker panels after the rear longitudinal crush structures have done their work to absorb the initial forces. While most crash standards are based on rear impacts at a speed of 50 km/h, General Motors safety standards raise this limit to 80 km/h.
High level of structural integrity
Structural integrity is critical to the crashworthiness of any vehicle and the body-frame-integral concept of the new Sonic provides the solid foundation of a strong and stiff body structure.
The unibody design consists of a high-strength steel structure incorporating full-length frame rails and a safety cage in a single welded unit. It is designed to combine with the front and rear crumple zones and provide the next level of protection once the crumple zones have done their work. The single piece side frames provide a continuous load path to effectively distribute crash impact energy around the occupants in the event of a head-on collision.
The safety cage is reinforced with welded tubular-section members that frame the door openings and support the roof. Beam reinforcements are fitted to the doors. The combination of a single piece door aperture and door beam reinforcements provides protection in the event of a side impact. Additional protection for side impacts comes from the use of ultra-high-strength steel in the strategic area around the forward portion of the side rockers and the centre cross member. Reinforcements to this area, situated directly under the front seats, have an ‘H’ form to provide excellent resistance to structural deformation.
A specific focus has been placed on limiting injuries to the lower leg and feet area of front occupants. The driver’s feet are protected by a pedal release system that folds away to prevent the feet and lower legs from being trapped in a severe front end impact. High-strength steel reinforcements are welded in place in the toe-pan area of the floor. On the passenger side the weld-pattern has been optimised to provide the maximum strength possible.
To compliment this inherently strong basic structure, the Sonic engineering team has embraced a number of additional safety features including airbag protection – frontal and seat side – for both front seat occupants.
A Sensing and Diagnostic Module (SDM) is mounted along the centreline of the vehicle. The SDM receives inputs from a number of sensors and determines the severity and location of any impact. It will then make a determination to deploy the airbags – side and front – and the seat belt pre-tensioners.
Three point lap and shoulder safety belts are provided for all passengers. The driver and front passenger belts have adjustable upper anchors to provide a comfortable fit for varying body shapes and sizes. Buckles are attached to the seats so the anchor point moves forward and back in synch with seat adjustment. ISOFIX child seat anchors are provided for the rear seats.
Pedestrian protection has been designed into the Sonic with refinements to the bonnet design and hinge structure incorporated to reduce the possibility of injuries caused by a pedestrian’s head or body impacting on the engine. This type of contact has been identified as a major source of serious injury in pedestrian accidents.
By increasing the space available between the engine and the bonnet, and by addressing the way in which the bonnet deforms on impact, the potential for serious injuries caused by contact with the engine and other “hard” under bonnet components has been significantly reduced.
The front bumper of the Sonic incorporates a foam energy absorber which surrounds the main bumper beam and lower bumper reinforcements to assist in cushioning pedestrian impacts.
The front and rear bumpers are engineered to require only minimal repairs following a minor impact at a speed of up to 4 km/h. Tests conducted to verify this performance include a head on impact with a flat barrier; 30-degree impact with a flat barrier, and rear straight-on impact with a flat barrier.