Segmented PC and ABS Sports Helmet Shell Design
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Solution Overview
Problem
Existing sports helmets, particularly for snow sports, face a challenge in achieving an optimal strength-to-weight ratio while ensuring impact resistance and meeting safety standards, with heavier ABS helmets risking rotational injuries and lighter PC helmets being less durable.
Innovation Solution
A safety helmet design featuring a thermoplastic polymer polycarbonate crown and acrylonitrile butadiene styrene skirt with an expanded polystyrene liner, co-moulded to enhance structural strength and impact resistance, using vacuum forming for the crown and injection moulding for the skirt to minimize weight and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an ABS shell is used to provide strength and durability, then impact resistance is improved, but weight increases which can cause rotational injuries
Solution Approach 1:
The helmet shell is divided into two distinct parts: a PC crown for the upper portion and an ABS skirt for the lower portion. This segmentation allows each material to be used where it provides the most benefit - PC for weight reduction in the crown area and ABS for impact resistance in the skirt area - thereby resolving the contradiction between strength and weight.
Solution Approach 2:
Different materials are applied to different regions of the helmet based on local requirements. The crown uses PC where weight reduction is prioritized, while the skirt uses ABS where impact resistance is more critical. This local differentiation of material properties allows optimization of the strength-to-weight ratio across the entire helmet structure.
2Weight of moving object
If a PC shell is used to reduce weight, then helmet weight is reduced, but durability and impact resistance deteriorate
Solution Approach 1:
The helmet is segmented into a PC crown and ABS skirt, allowing the lighter PC material to be used only where weight reduction is most beneficial (the crown), while the more durable ABS is used in the skirt where impact resistance is critical. This resolves the contradiction by applying materials strategically rather than uniformly.
Solution Approach 2:
The helmet employs a composite construction combining PC and ABS materials in a single shell structure. This composite approach allows the helmet to exhibit both the weight advantages of PC and the durability advantages of ABS, simultaneously resolving the contradiction between weight reduction and durability.
3Strength
If the shell is made thicker to improve strength, then impact resistance is improved, but the helmet appears bulkier and less fashionable
Solution Approach 1:
The composite PC/ABS construction provides enhanced structural strength that allows the shell to be made thinner while maintaining safety standards. The combination of materials creates a stronger structure per unit thickness, enabling a sleeker, more fashionable appearance without compromising protection.
Solution Approach 2:
The varying thickness and material distribution create an optimized structure where strength is concentrated where needed. The return edges and material distribution are designed to provide structural integrity with minimal material, achieving a balance between strength and aesthetic appearance.
4Strength
If ABS is used throughout the helmet to ensure durability, then impact resistance is improved, but manufacturing cost increases
Solution Approach 1:
The helmet is segmented into a PC crown and ABS skirt, using the more expensive ABS material only for the lower portion where impact resistance is most critical. This reduces the total amount of ABS required compared to using it throughout the entire helmet, thereby reducing manufacturing cost while maintaining necessary protection.
Solution Approach 2:
ABS material is applied locally to the skirt portion where it provides the most value for impact resistance, rather than being used uniformly across the entire helmet. This localized application optimizes the balance between protection and manufacturing cost by using expensive material only where most needed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves improved strength, reduced weight, and cost-effectiveness, allowing for a thinner, more durable helmet that is both safer and more aesthetically pleasing, addressing the limitations of traditional ABS and PC helmets.
Implementation Method 1
The inner shell may comprise a liner of expanded polystyrene, co-moulded with the outer shell
Implementation Method 2
vacuum forming a crown of thermoplastic polymer
Implementation Method 3
injection moulding a skirt of thermoplastic polymer
Data Source
AI summary
A safety helmet having an outer shell formed from a polycarbonate crown and an acrylonitrile butadiene styrene skirt, and an inner shell formed from expanded polystyrene. The inner shell is co-moulded with the outer shell.