Deformable Bolted Flange Spacers for Impact Load Absorption
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Solution Overview
Problem
Current deformable spacer designs in bolted joints are inefficient in absorbing energy and minimizing force transmission, leading to increased weight and cost in securing parts subjected to impact loads in engines and aircraft.
Innovation Solution
The use of deformable spacers with hollow cylindrical bodies and elongated slots or annular stiffeners that absorb energy through plastic deformation or shear failure, allowing for controlled buckling and energy absorption, reducing the need for heavier or larger bolts and flanges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the number and size of bolts are increased to withstand high magnitude forces, then the joint strength is improved, but the weight of the aircraft increases
Solution Approach 1:
A deformable spacer is introduced as an intermediary element between the bolt and the flange. This spacer absorbs impact energy through controlled plastic deformation, protecting the bolt from direct impact forces. The spacer acts as a buffer that dissipates energy, allowing the use of lighter bolts while maintaining joint integrity under impact loading conditions.
Solution Approach 2:
The spacer is designed with specific material properties and geometric parameters (such as wall thickness, length, and cross-sectional area) that control its plastic deformation behavior. By optimizing these parameters, the spacer can absorb predetermined amounts of energy, enabling the bolted joint to withstand impact loads with reduced bolt size and weight.
2Strength
If the size and thickness of flanges are increased to withstand impact loads, then the joint strength is improved, but the weight and cost increase
Solution Approach 1:
The deformable spacer serves as a protective intermediary between the impact load and the flange-bolt assembly. By positioning the spacer between the impact source and the critical joint components, it absorbs the harmful impact energy, allowing the flanges to be designed with reduced thickness and weight while maintaining adequate strength for the application.
3Loss of energy
If currently known deformable spacer designs are used, then some energy absorption is achieved, but the energy absorption efficiency is insufficient and force transmission to bolts is not minimized
Solution Approach 1:
The spacer's material properties (such as yield strength, elongation, and hardening characteristics) and geometric parameters (length, diameter, wall thickness) are carefully selected and optimized to achieve desired energy absorption performance. These parameter changes enable the spacer to undergo controlled plastic deformation that absorbs impact energy efficiently while limiting the force transmitted to the bolted joint.
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 deformable spacers effectively absorb impact loads, preventing damage to bolts and flanges while maintaining the integrity of the joint, enabling lighter and cost-effective designs for securing parts in high-stress applications.
Implementation Method 1
The deformable spacer may include a hollow cylindrical body... When a compressive axial load is applied to the hollow cylindrical body, the body outer diameter increases
Implementation Method 2
allowing for controlled buckling and energy absorption
Implementation Method 3
an annular stiffener extending inwardly from the body inner surface... The annular shoulder is configured to fail in shear when a compressive axial load exceeds a predetermined shear failure load
Implementation Method 4
Deformable spacers may be used with bolt and nut assemblies to absorb energy that may be applied to the bolt and nut assembly when impact loading occurs
Data Source
AI summary
Deformable spacers and spacer assemblies absorb energy when flange bolts are subjected to compressive axial loads by plastically deforming, failing in shear, rupturing or in a combination of failure modes so the flange bolts and the flanges connected thereby are not damaged. One deformable spacer may have a hollow cylindrical body with a plurality of elongated slots there through. Another deformable spacer may have an annular stiffener extending inwardly from an inner surface of a hollow cylindrical body. A spacer assembly may include an inner cylindrical body, and outer cylindrical body, and an annular shoulder extending from one of the bodies and engaged by the other body shears when a shear failure load is applied to the flange bolt. Another spacer assembly may include an annular belt around a cylindrical body so that the belt will rupture before the cylindrical body plastically deforms.