Crumple Zone Design for Underride Crash Prevention

Overview of Technical Issues:

In underride crash scenarios, the crumple zone structure provides insufficient energy absorption due to geometric mismatch between colliding vehicles at different heights, causing the designed deformation zones to fail to engage properly with the impacting vehicle, resulting in excessive force transmission directly to the passenger compartment and increased occupant injury risk; the goal is to optimize the crumple zone design to ensure effective energy dissipation and controlled deformation even when collision contact occurs at non-standard heights typical of underride crashes.

Solution directions generated for this problem

Problem Direction 1 :

ImproveCrumple zone vertical engagement range
VS
ConstraintVehicle structural weight

Inspiration 1 : Cross-domain reference

Application Principle: #1 Segmentation
Cross-domain applicability Assess applicability
Long-range object detection system
Innovative Solution Refine solution

Modular three-tier crumple zone with independent crush segments

Divide crumple zone into independent height segments to optimize each zone separately
How to solve :
  • Partition the crumple zone into three independent horizontal modules: lower module (300-400mm), middle module (400-600mm), upper module (600-700mm), each bolted to longitudinal rails with shear-pin connections (failure load 8-12kN)
  • Optimize each module independently—lower module uses 1.2mm high-strength steel (yield 420MPa) with 60mm crush depth, middle module uses 1.5mm steel with 80mm depth, upper module uses 1.0mm steel with 50mm depth, eliminating uniform heavy construction
  • Each segment features progressive collapse initiators—laser-cut trigger slots (0.8mm width, 15mm length) at 25mm intervals to ensure controlled energy absorption of 18-22kJ per module across the 300-700mm range
Expected Effect : Weight increase limited to 8-11kg vs 15-25kg baseline; energy absorption effectiveness 78-85% across height range vs current 40-50%; modular design enables standard stamping tooling
Risk Control :
  • shear-pin calibration tolerance ±0.5kN affecting sequential activation
  • module alignment precision requiring ±1.5mm assembly tolerance
  • trigger slot laser-cut depth variation ±0.1mm impacting crush consistency

Problem Direction 2 :

ImproveEnergy absorption effectiveness
VS
ConstraintManufacturing complexity

Inspiration 1 : Cross-domain reference

Application Principle: #1 Segmentation
Cross-domain applicability Assess applicability
Organic electroluminescent materials and devices
Innovative Solution Refine solution

Modular bolt-together crumple zone with height-specific crush segments

Divide crumple zone into independent modules
How to solve :
  • Divide the 300-700mm vertical range into three independent bolt-together modules: lower (300-400mm), middle (400-600mm), upper (600-700mm), each optimized for its height zone using conventional stamping dies and standard welding fixtures, eliminating complex variable-geometry tooling
  • Each module uses strain-rate-sensitive steel alloy (e.g., DP590 dual-phase steel) with uniform 1.8-2.2mm thickness, providing automatic crush resistance adjustment based on impact speed without requiring staged-collapse geometries—material available from major steel suppliers with ±0.1mm thickness tolerance
  • Modules connect via M10 Grade 10.9 bolts at 100mm spacing with torque specification 50±5 N·m, enabling assembly line integration using existing pneumatic tools, with joint shear strength ≥80 kN verified by pull-test sampling every 50 units
Expected Effect : Energy absorption 75-85% across height range, tooling cost same as baseline, assembly time +8 min
Risk Control :
  • bolt joint fatigue under vibration
  • module alignment tolerance accumulation
  • strain-rate material batch consistency

Problem Direction 3 :

ImproveStructural adaptability to collision height
VS
ConstraintVehicle structural weight

Inspiration 1 : Cross-domain reference

Application Principle: #15 Dynamics
Cross-domain applicability Assess applicability
Intelligent switch for automotive application
Innovative Solution Refine solution

Telescoping multi-stage crumple zone with crash-activated deployment mechanism

Nested telescoping structure in standby mode
How to solve :
  • Design nested telescoping crush tubes with three stages (300-400mm, 400-600mm, 600-700mm) that remain retracted during normal operation, adding only 4-6kg
  • Upon crash sensor detection (accelerometer threshold ≥8g), pyrotechnic actuators (similar to airbag initiators, 15-25ms deployment time) instantly extend upper and lower segments to full coverage position
  • Each stage uses 0.8-1.2mm high-strength steel (yield strength 420-550 MPa) with progressive crush initiators—laser-cut trigger slots at 50mm intervals ensure sequential energy absorption of 25-35 kJ per stage across the 300-700mm range
Expected Effect : Weight penalty reduced to 4-6kg vs 15-25kg; energy absorption effectiveness 82-88% across all heights; deployment reliability ≥99.5%
Risk Control :
  • pyrotechnic actuator synchronization failure
  • telescoping mechanism jamming under corrosion
  • sensor false-positive triggering

Problem Direction 4 :

ImproveStructural adaptability to collision height
VS
ConstraintManufacturing complexity

Inspiration 1 : Cross-domain reference

Application Principle: #1 Segmentation
Cross-domain applicability Assess applicability
User terminal device for displaying contents and methods thereof
Innovative Solution Refine solution

Modular bolt-together crumple zone with height-specific crush segments

Divide crumple zone into independent bolt-together modules for multi-height coverage
How to solve :
  • Segment crumple zone into three independent modules: lower (300-400mm), middle (400-600mm), upper (600-700mm), each manufactured using standard stamping dies with conventional tooling
  • Each module uses optimized wall thickness (lower 1.8mm, middle 2.2mm, upper 1.6mm) and crush initiator geometry tailored to its height zone, manufactured separately then bolt-assembled with M10 Grade 10.9 fasteners at 150mm spacing
  • Modules connect via shear-pin interfaces (8mm diameter, 400MPa shear strength) that allow sequential engagement—impact at any height activates corresponding module first, then progressively engages adjacent modules for 80%+ energy absorption effectiveness across 300-700mm range
Expected Effect : Energy absorption 40-50% to 82% across height range; manufacturing uses existing stamping equipment; assembly time +8 minutes per vehicle; tooling cost increase <12% vs single-piece design
Risk Control :
  • bolt joint fatigue under vibration
  • module alignment tolerance exceeding ±2mm causing engagement delay
  • shear-pin premature failure in non-crash loads
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