Automotive glazing — behavior of laminated glass on impact When laminated safety glass cracks in service, it typically:

Difficulty: Easy

Correct Answer: has its sandwiched interlayer trap and retain the glass fragments

Explanation:


Introduction / Context:
Vehicle glazing uses different glass types for safety: tempered (toughened) glass and laminated glass. Understanding how laminated glass fails is important for occupant protection and for first responders who must manage broken glass safely.


Given Data / Assumptions:

  • Laminated glass comprises two glass sheets bonded by a polyvinyl butyral (PVB) or similar interlayer.
  • Used commonly for windshields; side and rear windows may be tempered.
  • Impact or crack growth is considered, not explosive shattering from extreme conditions.


Concept / Approach:
Laminated glass is designed so that when either ply fractures, the interlayer holds fragments together. This prevents ejection of shards, maintains a barrier against ejection of occupants, and reduces laceration risk. Tempered glass, by contrast, fractures into many small granular pieces that usually fall away from the opening.


Step-by-Step Solution:
Identify the construction: glass–interlayer–glass sandwich.Recognize the failure mode: cracking with fragments adherent to interlayer.Select the option describing fragment retention by the sandwiched layer.


Verification / Alternative check:
Crash tests and manufacturer literature show windshield ‘‘spider web’’ cracking patterns while remaining largely intact due to the PVB interlayer adhesion.


Why Other Options Are Wrong:
Sharp-edged fragments typically describe annealed glass. Granular pieces describe tempered glass. Crystal-like shards are not the intended failure mode of laminated safety glass.


Common Pitfalls:
Assuming all vehicle glass behaves the same; in many regions only the windshield must be laminated, while other windows are tempered.


Final Answer:
has its sandwiched interlayer trap and retain the glass fragments

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