07b Vehicle Structural design Flashcards
Body Structure Attributes (7)
- Durability
- Passive Safety
- Weight
- Solidity
- Water-tightness
- Corrosion
- NVH (Noise, Vibration, and Harshness)
Body architectures:
- Unibody (most commun)
- Space frame (old racecar)
- Body-on-frame (Pick up)
- Monocoque (F1)
Unibody Advantages/ Disadvantages
Concept
- Load carrying body structure built up by stamped metal sheets
Advantages
- Suitable for mass production
- Strong and light
- Deformation zones for crash
Disadvantages
- Expensive for low volume models due to stamping tools
Space frame Advantages/ Disadvantages
Concept
- Load carrying body structure built up by tubes &profiles
Advantages
- Low weight
- Less investments than unibody (extruded profiles)
Disadvantages
- Not suited for large volumes
Body-on-frame Advantages/ Disadvantages
Concept
- Body structure bolted to load carrying frame
Advantages
- High comfort with body insulated from frame
- Suited for heavy duty service (trucks, buses, etc.)
Disadvantages
- Heavier than unibody and space frame
- Less resistant to torsion than unibody
- Poor deformation zones
Battery installation (2 Types)
- Layer on Layer Structural design
- Fully integrated Structural design
Steel A/D
Advantages
* Enormous experience (forming, joining, corrosion, etc.)
* Well established simulation tools (FEA for strength, crash, durability, etc.)
* Large palette of steel grades (from mild steel to ultra high strength steel)
* Low cost (as compared to aluminum, stainless steel, etc.)
Disadvantages
* Heavier than, for instance, aluminum
Aluminum A/D
Advantages
* Low weight (density is 1/3 of steel)
* Simulation tools fairly mature (FEA for forming, strength, crash, durability, etc.)
* Joining methods well established (rivets, seam welds, adhesive, etc.)
* Castability and realization of complex shapes and part integration
Disadvantages
* Low stiffness (modulus of elasticity is 1/3 of steel)
* Low strength as compared to steel
* More expensive than steel (more than 2 times)
Basic safety principles (Zones)
- Progressive deformation zone for frontal impact
- Strong ”safety cage” with as little deformation as possible
- Progressive deformation zone for rear impact
Frontal impact – Barrier impact EURO vs US
Euro-NCAP
* 40 mph = 64 km/h, 40% overlap
* Deformable barrier Requires a strong front structure and a strong back-up structure!
US-NCAP (Rare in real life!)
* 35 mph = 56 km/h, 100% overlap
* Rigid barrier
A strong front structure might cause a pulse problem!
Major factors affecting crash performance (3)
Size, Strength, Weight
Side impact - Structural principles (6)
- Multiple load paths
- Roof strength independent of stdroof or Pano
- Strong B-pillar, sill & cantrail
- Strong A-pillar & front header
- Door beams with optimized positions
- Safety cage designed for overload
