10 10 10 10 10 THE AUTOMOTIVE ENGINEER September | October 2007 September | October 2007 September | October 2007 September | October 2007 September | October 2007 Medium Strength 23% Low Carbon 77% Medium Strength 32% High Strength Steel 36% Low Carbon 19% Advanced High Strength Steel 10% Ultra High Strength Steel 3% STEEL USAGE: MY07 to MY06 VE: 81% Advanced Steel VZ VE We included a general overview of the new VE Commodore in the September/October 2006 edition of “The Automotive Engineer.” At the launch of the VE, safety was a priority at every phase of this new design with the General spending big bucks on safety engineering programs that culminated in delivering a stiffer body structure, improved occupant protection and the vastly increased use of advanced strength steels. Exclusive vehicles from the world’s top brands were used to benchmark safety technologies, packaging and performance in various types of impacts. Body structure design complemented passive safety technology such as the acclaimed crash avoidance system, Electronic Stability Program (ESP®), which is standard on all VE sedans. It also provided for front, side and curtain airbag systems to be offered as standard or optional on all VE models. Given the extensive safety advancement and technology available on VE, engineers believed an overall mass gain compared with the previous generation Commodore was a worthy balance. High Strength Steels in the VE Commodore B O D Y W O R K S Body Structure The fundamental principle is to minimise intrusion and thereby provide increased occupant protection. Holden put a lot of work into tuning the front and rear of the vehicle, with structurally optimised crush zones to absorb crash energy. The pie chart shows steel material usage on VE compared to VZ. A high percentage of high strength steel gives greater structural rigidity and maximises sectional efficiency.
Transcript
1010101010 THE AUTOMOTIVE ENGINEERSeptember | October 2007September | October 2007September | October 2007September | October 2007September | October 2007
Medium Strength 23%
Low Carbon 77%
Medium Strength 32%
High Strength Steel 36%
LowCarbon 19%
Advanced HighStrength Steel 10%
Ultra HighStrengthSteel 3%
STEEL USAGE: MY07 to MY06
VE: 81% Advanced Steel
VZ
VE
We included a general overview of the new VE Commodore in the September/October2006 edition of “The Automotive Engineer.” At the launch of the VE, safety was a priorityat every phase of this new design with the General spending big bucks on safetyengineering programs that culminated in delivering a stiffer body structure, improvedoccupant protection and the vastly increased use of advanced strength steels.Exclusive vehicles from the world’s top brands were used to benchmark safety technologies, packaging andperformance in various types of impacts. Body structure design complemented passive safety technology such asthe acclaimed crash avoidance system, Electronic Stability Program (ESP®), which is standard on all VE sedans. Italso provided for front, side and curtain airbag systems to be offered as standard or optional on all VE models.
Given the extensive safety advancement and technology available on VE, engineers believed an overall mass gaincompared with the previous generation Commodore was a worthy balance.
High Strength Steels in theVE Commodore
B O D YW O R K S
Body StructureThe fundamental principle is to minimise intrusion and thereby provide increased occupant protection. Holden put alot of work into tuning the front and rear of the vehicle, with structurally optimised crush zones to absorb crashenergy. The pie chart shows steel material usage on VE compared to VZ. A high percentage of high strength steelgives greater structural rigidity and maximises sectional efficiency.
Virtual PhaseThe virtual crash modelling program was by far thebiggest Holden has undertaken, they ran more than5,000 barrier tests using leading–edge virtualtechnology. It would take five years plus – at three testsa day, every day – to do those barrier tests in reality.
Crash PerformanceThere was a huge amount of work done on the crashstructure to get it right. Significant crash performanceobjectives drove the design to meet offset frontal, fullfrontal, rear and side impact requirements.
The big challenge was to meet crash requirements,despite VE’s new design reducing crush space, due toits very short overhang. To do this, Holden used high–strength steels and a very careful design of the front railsection and the joints. To minimise passengercompartment intrusions, clearly defined load paths forfrontal, side and rear impact are included.
For frontal impact, facilitators are the three load paths whichhave been created through the upper rails, longitudinal railsand the engine cradle. For side impact, load paths includethe B pillar, instrument panel cross–beam, three floor cross–members, rocker, door intrusion beam and structural roofbow design. For rear impact, the strategy involved the rearlongitudinal rail, rocker and C pillar brace design.
Compartment integrity is maximised by the employmentof multiple load paths and usage of very high strengthsteel, particularly in the side structure.
Note, the high strength steel usage, the red, primarily in thefront and rear load paths. And the yellow and green areas inthe side structure indicate advanced and ultra high–strengthsteels, designed to minimise deformation or intrusion.
High-strength steels have tensile strengths of between 270 –700Mpa, advanced high–strength steels start at 400Mpa, andultra–high–strength steels are those greater than 700Mpa.
1111111111THE AUTOMOTIVE ENGINEERSeptember | October 2007September | October 2007September | October 2007September | October 2007September | October 2007
Mass / Material Utilisationand Body Stiffness
Weight is a key issue in any body structure architecturalprogram. With VE, the focus was on keeping weight outof the panels rather than the structure. By successfullybenchmarking against European luxury cars and GM’sown large passenger vehicles, GM have achieved anextremely high level of body stiffness. Torsion andbending modes, driven by stringent crash and noise andvibration requirements, have increased enormously.
To briefly explain what torsion and bending modes haveto do with structural twisting and bending under appliedloads – such as road and suspension inputs. The higherthe figure, the better the result. GM’s initial target was45 hertz for torsion and bending and VE has achieved55 hertz for the structure only. This is a world classresult. The cockpit is now an integral part of the cross–car structure – a huge improvement in terms of bodystiffness and dimensional capability.
VE’s one-piece body side outer is the biggest panelHolden has ever produced. It replaces the current two–piece side and delivers quality improvements such asdimensional stability and repeatability. Along with otherenablers such as full frame doors, these measuresprovide better fit and finish, improved crashperformance and reductions in noise and vibration.
Important Body Repair ProcedurePersons undertaking body repairs are required to havea thorough knowledge on the repair of high–stengthsteels. At no time should high–strength steels be subjectto heating in an effort to straighten or reform the high–strength body member to its original design or shape.
Extra care must also be taken when welding high–strengthsteels so as not to apply excessive heat. Heat can changethe properties of high–strength metals and the once pre-accident strong body component may now fail to supportthat section of the vehicle again in an accident.
If in doubt on the correct repair procedure of high–strength metals always refer to the motor vehiclemanufacturer for advice.
This report was possible with the kind cooperation of GM Holden Ltd.
Load Path StrategyFRONTAL IMPACT
Load Path StrategySIDE IMPACT
Load Path StrategyREAR IMPACT
1212121212 THE AUTOMOTIVE ENGINEERSeptember | October 2007September | October 2007September | October 2007September | October 2007September | October 2007
