Unidirectional Roofing Arch Tensioning Device
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Solution Overview
Problem
Existing connecting devices for roofing arches fail to maintain tension in flexible roofing fabrics under varying loads, such as snow, leading to arch compression and fabric relaxation, which can result in water pocket formation.
Innovation Solution
A unidirectional connecting device with a threaded rod and pivot jaws that allows upward displacement of arches to maintain tension but prevents downward movement under load, using a spring and Belleville washers to compensate for fabric creep and prevent water pocket formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the connection device allows bidirectional movement of arches, then the fabric can accommodate both creep relaxation and load compression, but the arches will lower under snow load causing fabric slackening and water pocket formation
Solution Approach 1:
The connection device transitions from a static fixed connection to a dynamic unidirectional connection that allows controlled movement in one direction (upward) while preventing movement in the opposite direction (downward). The jaw mechanism with spring bias enables the arch to move upward to compensate for fabric creep but blocks downward movement under snow load, maintaining fabric tension reliability.
Solution Approach 2:
The invention extracts the downward movement constraint from the bidirectional connection system, creating a unidirectional connection that selectively permits upward movement while eliminating downward movement capability. This is achieved through the jaw design that engages with the arch profile to prevent downward displacement while allowing upward displacement during installation and creep compensation.
2Stability of the object's composition
If the connection device uses a fixed rigid connection, then the arch position is stable, but the fabric tension relaxes due to creep and cannot be compensated
Solution Approach 1:
The connection device transforms from a static rigid connection to a dynamic connection with controlled mobility. The jaw mechanism allows upward movement of the arch relative to the support structure, enabling the system to adapt to fabric creep while maintaining stable positioning under load through the unidirectional constraint.
Solution Approach 2:
The spring element is pre-loaded during installation to store elastic energy that will compensate for future fabric creep. The jaw mechanism is positioned to allow upward movement, and the spring is compressed to create a predetermined force that will push the arch upward as the fabric relaxes over time.
3Reliability
If the connection device allows upward movement to compensate for creep, then fabric tension is maintained, but the arch may move away from the structure under normal conditions
Solution Approach 1:
The jaw mechanism creates asymmetric movement constraints by permitting upward movement while blocking downward movement. The geometry of the jaw and arch profile is designed so that the jaw can rotate and slide upward but is mechanically blocked from moving downward, creating different force transmission characteristics in opposite directions.
Solution Approach 2:
The connection device employs dynamic behavior where the arch can move upward relative to the support structure during creep compensation but is constrained to remain fixed relative to the structure under downward load. The spring element provides a variable force that adapts to the fabric tension state, allowing movement when needed and providing rigid support when required.
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 device effectively maintains the tension of the roofing fabric within a recommended range, preventing water pocket formation by allowing arches to move away from the structure during creep while blocking downward movement under load, thus ensuring the fabric remains taut even under significant snow loads.
Implementation Method 1
using a spring and Belleville washers to compensate for fabric creep
Implementation Method 2
The device effectively maintains the tension of the roofing fabric within a recommended range
Data Source
Figure 1
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AI summary
This connecting device (1) is intended to be installed on a building structure (130) to tension a flexible roofing fabric (110) fixedly attached at its periphery to the building structure. The connecting device comprises: - an arch (150) against which the roofing fabric (110) is tensioned, - elastic prestressing reserve means interposed between the structure and the arch (150) to compensate for creep in the roofing fabric (110), and - unidirectional displacement means for the arch (150) relative to the structure, allowing the arch (150) to move away from the structure towards the roofing fabric (110) when the prestressing reserve means are released, and preventing the arch (150) from moving in the opposite direction towards the structure under the effect of a load applied to the roofing fabric. (110).