Crumple Zone Design for Small Overlap Frontal Crashes
Overview of Technical Issues:
In small overlap frontal crashes, the crumple zone structure provides insufficient energy absorption because impact forces bypass the primary longitudinal energy-absorbing members and instead load the outboard structures, creating a harmful direct transmission pathway where uncontrolled crash energy intrudes into the passenger compartment through the wheel, suspension, A-pillar, and dash panel, resulting in excessive occupant space intrusion and increased injury risk; the goal is to optimize the crumple zone to effectively absorb energy and guide loads even in 25% overlap crash scenarios while maintaining structural integrity of the passenger compartment.
Solution directions generated for this problem
Problem Direction 1 :
ImproveOutboard structure energy absorption capacity
VSConstraintStructural mass
Inspiration 1 : Cross-domain reference
Application Principle: #1 Segmentation
Cross-domain applicability
Tray for cooking food and process for manufacturing a tray
Innovative Solution Refine solution
Modular multi-chamber wheel well energy absorber with independent crush zones
Divide wheel well into independent crush chambers
How to solve :
- Partition the wheel well structure into three independent crush chambers (upper suspension tower zone, mid-wheel housing zone, lower A-pillar interface zone), each optimized for local load magnitude and direction rather than uniform reinforcement
- Each chamber uses tailored wall thickness gradients (2.0mm outer, 3.5mm mid, 2.5mm inner) and geometric crush initiators (hexagonal embossments 8mm deep, 40mm spacing) to control progressive collapse sequence and energy dissipation rate
- Chambers connected via shear-pin joints (6mm diameter, 420MPa yield strength) that sequentially fail at predetermined loads (Chamber-1: 45kN, Chamber-2: 65kN, Chamber-3: 85kN), ensuring staged energy absorption totaling 18-22kJ while adding only 6-8kg using DP590 dual-phase steel
Expected Effect : Energy absorption 62-68%, mass addition 6-8kg (67% reduction vs uniform reinforcement), intrusion reduced to 68-72mm
Risk Control :
- shear-pin calibration tolerance ±5% affecting failure sequence
- chamber wall thickness variation exceeding ±0.15mm reducing crush predictability
- welding heat-affected zones altering local material properties
Problem Direction 2 :
ImproveLoad path distribution effectiveness
VSConstraintManufacturing complexity
Inspiration 1 : Cross-domain reference
Application Principle: #1 Segmentation
Cross-domain applicability
User terminal device for displaying contents and methods thereof
Innovative Solution Refine solution
Modular bolt-together outboard load redistribution system
Divide adaptive load path into modular segments
How to solve :
- Partition the outboard load redistribution structure into three independent bolt-together modules: wheel well energy bracket (stamped 1.8mm DP590 steel), suspension tower adapter plate (laser-cut 2.5mm DP780), and A-pillar connector bracket (formed 2.2mm UHSS) — each manufactured separately using conventional stamping/cutting processes with standard ±0.3mm tolerances, eliminating complex hot-forming and multi-material welding
- Implement standardized bolt interface design with M10 Grade 10.9 bolts at 80mm spacing, torque specification 45±3 N·m, enabling assembly with existing fixturing and pneumatic tools without specialized welding equipment or skilled labor
- Design each module with progressive thickness transitions (1.8mm→2.5mm→2.2mm across load path) that naturally guide crash forces from wheel well through suspension tower to A-pillar base, achieving 62% energy absorption in 25% overlap scenarios while maintaining A-pillar intrusion <75mm
Expected Effect : Energy absorption 30%→62%, manufacturing cost +8% vs +35% for integrated design, assembly time 12 min per vehicle
Risk Control :
- bolt joint fatigue under cyclic loading
- module alignment precision during assembly
- corrosion at bolted interfaces
Problem Direction 3 :
ImproveStructural integrity under offset loading
VSConstraintStructural mass
Inspiration 1 : Cross-domain reference
Application Principle: #1 Segmentation
Cross-domain applicability
Handheld device enclosure
Innovative Solution Refine solution
Modular three-segment A-pillar reinforcement with zone-specific material distribution
Divide A-pillar into three independent modules with optimized materials per zone
How to solve :
- Divide A-pillar reinforcement into three bolt-together segments: lower base plate (0-300mm, hot-stamped boron steel 1500MPa, 1.2mm thickness), mid-section stiffener (300-600mm, DP780 steel, 1.0mm), upper bracket (standard HSLA steel, 0.8mm)
- Each segment manufactured separately using conventional stamping dies, assembled via M8 Grade 10.9 bolts at 150mm spacing with ±0.3mm hole tolerance, eliminating complex single-piece hot-stamping
- Install crushable aluminum honeycomb blocks (6061-T6, 50mm thickness, 3-5mm cell size) between wheel well and lower A-pillar base as sacrificial energy absorbers, pre-compressed to 10% strain
Expected Effect : A-pillar intrusion reduced to <70mm; mass addition limited to 6-8kg (65% lighter than uniform reinforcement); energy absorption 55-65%
Risk Control :
- bolt joint fatigue under cyclic loading
- honeycomb block positioning accuracy
- segment interface load transfer efficiency
Problem Direction 4 :
ImproveStructural integrity under offset loading
VSConstraintManufacturing complexity
Inspiration 1 : Cross-domain reference
Application Principle: #1 Segmentation
Cross-domain applicability
Elastic laminates and methods for assembling elastic laminates for absorbent articles
Innovative Solution Refine solution
Modular bolt-together A-pillar reinforcement system with segmented load zones
Divide A-pillar reinforcement into modular segments for simple assembly
How to solve :
- Design three-segment A-pillar reinforcement: lower base plate (0–300mm), mid-section stiffener (300–600mm), upper connector (600mm+), each stamped separately using conventional dies with ±0.5mm tolerance
- Connect segments via pre-positioned bolt holes (M10 Grade 10.9 bolts, torque 45±3 N·m) with standardized flange interfaces, eliminating complex hot-stamping and laser welding
- Apply hot-stamped boron steel (1500 MPa) only to lower segment where intrusion occurs, standard HSLA 590 MPa steel for mid/upper sections, reducing advanced forming by 65%
Expected Effect : A-pillar intrusion <75mm; manufacturing complexity reduced 60%; cycle time -40%
Risk Control :
- bolt joint fatigue under cyclic loading
- segment alignment precision during assembly
- interface stress concentration at bolt locations
