Safety Harness Leg Straps with Groin Recesses
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Solution Overview
Problem
Standard safety harnesses cause orthostatic shock, known as 'hanging trauma', within 20 minutes due to compression of the femoral vein, leading to reduced hanging time and increased mortality risk in rescue situations.
Innovation Solution
The safety harness design features leg straps with recesses to keep the femoral vein partially free, using compressible pads positioned around the pelvic area to dissipate belt forces and prevent external interference with blood flow, ensuring no compression of the vein for at least 50 mm in either direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard safety harnesses are used with leg straps that compress the groin area, then the harness provides adequate support and distribution of forces, but the femoral vein is compressed causing reduced blood flow and orthostatic shock within 20 minutes
Solution Approach 1:
The leg strap incorporates a local recess in the groin area that excludes compression of the femoral vein while maintaining overall harness support function. This localized structural modification allows the harness to provide adequate support forces without harmful compression to the vein, resolving the contradiction between reliability and harmful effects.
Solution Approach 2:
The leg strap is segmented into functional zones: a compression zone for force distribution and a recessed zone to protect the femoral vein. This segmentation allows different parts of the same component to perform different functions - providing support where needed while avoiding compression where harmful.
2Force
If the leg strap compresses the groin area to provide adequate support, then force distribution is improved, but hanging time is reduced due to orthostatic shock
Solution Approach 1:
The recess in the leg strap creates a local quality difference that preserves femoral vein patency while maintaining overall force distribution capability. This allows the harness to extend hanging time by avoiding venous compression, directly resolving the contradiction between force distribution and duration.
3Ease of operation
If padding is added to the leg strap to protect the groin area, then comfort and pressure distribution are improved, but the padding may compress the femoral vein if not carefully designed
Solution Approach 1:
The padding is strategically positioned away from the femoral vein location through the recess design. This local quality differentiation allows comfortable padding for pressure distribution while explicitly excluding the vein from the compressed zone, resolving the contradiction between comfort and harmful effects.
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
This design significantly extends hanging time by minimizing venous blood return restriction, delaying orthostatic shock and reducing mortality rates during rescue operations.
Implementation Method 1
The pads can be made of the same or different material. Due to human anatomy, the vena femoralis is located in the middle groin area approx. 100 - 200 mm away from the spina iliaca anterior superior
Implementation Method 2
two leg strap pads on each side made of compressible material in such a way that external interference with the blood flow through the femoral vein in the groin area is avoided
Data Source
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AI summary
Safety harnesses for the human body, having two leg harnesses for two human legs, wherein at least one of the leg harnesses has an opening which is arranged in such a way as to keep the Vena femoralis at least partially free.