Deformable Joint Assembly for Composite Gas Turbine Casings
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Solution Overview
Problem
Existing joint assemblies for gas turbine engine casings, particularly those made of composite materials, face impracticality due to the need for large load spreaders and hole reinforcements to prevent damage, which increase weight and complexity, especially during extreme dynamic events like fan-blade-off scenarios.
Innovation Solution
A joint assembly featuring a first component with a flange and a second component with elongate cavities, where fixation devices include bolts with extendable shanks and embedded nuts that can deform to absorb energy and reduce clamping force, allowing for load distribution and accommodating lateral displacement without the need for separate load spreaders, and optionally using crushable or elastically deformable collars to manage axial loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If large load spreaders and hole reinforcements are used to prevent damage to composite materials, then the strength and reliability of the joint assembly is improved, but the weight and complexity of the assembly increases substantially
Solution Approach 1:
The joint assembly is divided into modular components: fixation devices with embedded nuts, elongate cavities in the joining portion, and separate flange components. This segmentation allows each component to be optimized independently, eliminating the need for oversized load spreaders while maintaining joint strength.
Solution Approach 2:
The nut is embedded within the joining portion of the second component, with the bolt shank passing through the flange and into the cavity containing the nut. This nested configuration integrates the fastening function directly into the structural component, eliminating the need for separate load spreader elements.
2Reliability
If extendable bolt shanks and deformable fixation devices are used to absorb energy and accommodate lateral displacement, then the reliability during extreme events is improved, but the device complexity increases
Solution Approach 1:
The fixation devices are designed with deformable characteristics that allow them to dynamically respond to extreme loads. The embedded nuts within elongate cavities can accommodate lateral displacement and rotation, allowing the joint to absorb energy from surge pulses and fan-blade-off events without fracturing.
Solution Approach 2:
The mechanical properties of the fixation devices are designed to change under different load conditions. The deformable collar and extendable shank allow the fixation device to transition from a rigid clamping state during normal operation to a more compliant state during extreme events, absorbing energy while maintaining attachment.
3Adaptability or versatility
If the fixation device is made deformable to remove clamping force under axial loads, then the ability to accommodate forced orbiting is improved, but the clamping force stability deteriorates
Solution Approach 1:
The deformable collar provides partial compliance only when needed - during extreme events with high axial loads. Under normal operating conditions, the collar remains rigid and maintains stable clamping force. The deformability is activated only when the axial load exceeds the design threshold, allowing forced orbiting accommodation without compromising normal clamping stability.
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 joint assembly effectively absorbs energy during extreme events, maintains attachment of casings, and reduces vibration transmission, while minimizing damage to composite materials by distributing loads and allowing for necessary movement without the need for additional reinforcements, thus enhancing reliability and reducing weight.
Implementation Method 1
the fixation device is configured such that under axial loads less than those causing bolt failure the fixation device is deformable to remove the clamping force across the flange and the end surface
Implementation Method 2
the fixation device is deformable to remove the clamping force across the flange and the end surface
Implementation Method 3
optionally using crushable or elastically deformable collars to manage axial loads
Implementation Method 4
reduces vibration transmission, while minimizing damage to composite materials by distributing loads and allowing for necessary movement
Data Source
AI summary
A joint assembly includes a first component with a flange containing a plurality of spaced through-holes; a second component with a joining portion having an end surface which faces the flange and containing a plurality of spaced elongate cavities; and a plurality of fixation devices. Each cavity extends into the joining portion from the end surface in alignment with one of the through-holes. Each fixation device includes: a bolt which extends through a respective through-hole and the corresponding cavity, and includes a nut which is embedded within the joining portion at the corresponding cavity to receive the bolt such that on tightening the nut and bolt a clamping force is exerted across the flange and the end surface to join the first and second components together. Under axial loads less than that causing bolt failure, each fixation device is deformable to remove the clamping force.