Hinged Coupling Device with Segmented Compression and Tension Rods
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Coupling devices in hinged elements, such as those used in aircraft nacelles, experience fatigue due to alternating compressive and tensile stresses, leading to material weakening and the need for oversized or redundant components for safety, resulting in increased weight, cost, and size.
Innovation Solution
A coupling device with a compression element that transmits compressive loads and a tension element that transmits tensile loads, where the compression element can substitute for tensile loads in case of tension element failure, allowing for a smaller tension element and reduced stress on both rods, with elongate openings for hinge pins to accommodate movement and misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single rod is used to transmit both compressive and tensile loads, then the coupling device is simpler in structure, but the rod is subjected to fatigue stresses leading to material weakening and requiring oversized or redundant components
Solution Approach 1:
The coupling device is segmented into two separate rods: a compression rod for transmitting compressive loads and a tension rod for transmitting tensile loads. This segmentation allows each rod to be optimized for its specific load type, eliminating fatigue issues caused by alternating stress cycles in a single rod.
Solution Approach 2:
Each rod is designed with specific local properties suited to its function. The compression rod is optimized for compressive strength while the tension rod is optimized for tensile strength. This local quality optimization allows each component to be precisely sized for its specific load case without requiring oversizing for fatigue safety margins.
2Reliability
If the rod is made larger or additional rods are provided for safety against fatigue, then the reliability is improved, but the weight, cost, and size of the coupling device increase
Solution Approach 1:
By segmenting the load transmission function into separate compression and tension rods, each rod can be sized optimally for its specific load case rather than requiring a single oversized rod to handle all load conditions with fatigue safety margins.
Solution Approach 2:
The design changes the stress state parameter for each rod, ensuring the compression rod experiences only compressive stresses and the tension rod experiences only tensile stresses. This parameter control eliminates fatigue cycling, allowing lighter weight components.
3Volume of moving object
If a single rod handles both compression and tension, then the device is more compact, but the rod experiences alternating stresses causing fatigue and requiring larger dimensions
Solution Approach 1:
The coupling device is divided into separate compression and tension elements, allowing each to be optimized for its specific load type. This segmentation enables more efficient use of material strength since each element experiences only one type of stress, avoiding the strength reduction caused by fatigue in alternating stress conditions.
Solution Approach 2:
Each rod is designed with local quality optimized for its specific function - the compression rod for compressive loading and the tension rod for tensile loading. This allows each component to achieve maximum strength efficiency for its designated load case without compromising overall device compactness.
Data Source
AI summary
Disclosed is a coupling device (1) intended to connect first and second elements which are articulated with respect to one another, wherein the device includes a compression element (2) designed to allow a compressive force to pass from one element to another in a first state, and a tension element (3) designed to allow a tensile force to pass from one element to another in a second state, the compression element additionally forming a substitution tension element designed to allow a tensile force to pass from one element to another in a third state corresponding to the fracturing of the tension element.