Polycarbonate Shield Air Gap Impact Dissipation
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Solution Overview
Problem
There is a need for a protective shield that can prevent or mitigate the complete penetration of flying debris, such as rocks and sheared metal bits, during mining and excavating operations, and must be releasably mounted on various machines to protect operators from injury.
Innovation Solution
A protective shield comprising a base layer of transparent polycarbonate layers with a sacrificial polycarbonate layer and an air gap, where all polycarbonate layers have the same ripple orientation to enhance optical clarity and durability, and can be mounted on vehicles like excavators to prevent penetration of projectiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single layer of thick polycarbonate is used, then penetration resistance is improved, but optical clarity and impact distribution deteriorate
Solution Approach 1:
The shield is divided into multiple polycarbonate layers (typically 3-5 layers) of moderate thickness rather than using a single thick layer. Each layer is approximately 0.125 to 0.25 inches thick, which maintains optical clarity while collectively providing superior penetration resistance through cumulative structural integrity and impact distribution across multiple interfaces.
Solution Approach 2:
The shield uses a composite structure of multiple polycarbonate layers with different ripple orientations. The layers are optically bonded together to create a composite material that combines the transparency of individual layers with enhanced strength from the multi-layer configuration, achieving both optical clarity and penetration resistance.
2Strength
If multiple polycarbonate layers are used, then penetration resistance is improved, but manufacturing complexity increases
Solution Approach 1:
All polycarbonate layers are made from the same material (polycarbonate) with consistent properties, ensuring uniform optical characteristics and mechanical strength throughout the shield. This homogeneity simplifies manufacturing by eliminating the need to source and handle different materials, while still achieving enhanced penetration resistance through the multi-layer configuration.
Solution Approach 2:
The ripple orientation is predetermined and pre-established in each layer during manufacturing, with alternating layers having opposite ripple directions. This preliminary configuration of ripple patterns before assembly simplifies the bonding process and ensures optimal impact distribution without requiring complex alignment procedures during assembly.
3Strength
If polycarbonate layers with different ripple orientations are used, then impact distribution is improved, but optical clarity deteriorates
Solution Approach 1:
The harmful effect of ripple interference is extracted and eliminated by using thin enough layers that their individual ripple patterns become imperceptible when viewed through the complete multi-layer assembly. The moderate thickness of each layer (0.125 to 0.25 inches) is specifically chosen to minimize ripple visibility while maintaining structural integrity.
Solution Approach 2:
The ripple orientation alternation, which would normally create visual interference in a single plane, is transformed into a three-dimensional structural feature that enhances impact distribution. The alternating patterns in successive layers create a staggered configuration that deflects and distributes impact forces throughout the shield's volume, converting a potential optical defect into a mechanical advantage.
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 shield effectively prevents penetration of projectiles, maintaining structural integrity and optical clarity, and can be easily replaced and refurbished, reducing machine downtime and operator risk.
Implementation Method 1
an air gap positioned directly between at least a portion of the base layer and the sacrificial polycarbonate layer
Implementation Method 2
each polycarbonate layer (e.g., single-layered base layer, individual polycarbonate layers forming a laminate base layer, and the sacrificial polycarbonate layer) includes a respective ripple orientation and each respective ripple orientation may be oriented in the same direction
Data Source
AI summary
Protective shields configured to prevent projection against projectiles, such as during excavating and/or mining operations, are provided. The protective shields include a base layer comprising one or more transparent polycarbonate layers, a sacrificial polycarbonate layer comprising a transparent polycarbonate, and an air gap positioned directly between at least a portion of the base layer and the sacrificial polycarbonate layer. The sacrificial polycarbonate layer is directly or indirectly attached to the base layer in a manner to provide the air gap positioned between the base layer and the sacrificial polycarbonate layer.