Variable-Stiffness Clamp Spring for Uniform Riser Load Distribution
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Solution Overview
Problem
Existing clamps for buoyancy modules on tubular members like risers face challenges in distributing radial loads evenly due to variations in riser diameter and bending strains, leading to potential collapse or misalignment of the riser configuration.
Innovation Solution
A spring with varying stiffness along its length, featuring undulating or voided surfaces, is designed to distribute load more evenly by increasing stiffness at the ends and reducing it at the center, ensuring uniform pressure distribution and preventing tubular member collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid clamp is used to secure buoyancy modules to risers, then the clamp provides strong holding force, but it causes uneven pressure distribution and potential riser collapse due to diameter variations and bending strains
Solution Approach 1:
The spring is designed with non-uniform cross-sectional dimensions along its length, creating varying stiffness characteristics in different regions. The ends have higher stiffness to prevent slip, while the center has lower stiffness to conform to riser diameter variations and distribute pressure evenly, avoiding localized stress concentrations that could cause collapse.
Solution Approach 2:
The spring's physical parameters (cross-sectional area, thickness) are changed along its length to create a stiffness gradient. This parameter variation allows the spring to adapt its mechanical properties to different functional requirements along its span, achieving both secure holding and uniform pressure distribution.
2Ease of manufacture
If a uniform stiffness spring is used, then the manufacturing is simple, but the spring cannot adapt to riser diameter variations and bending strains
Solution Approach 1:
The spring incorporates localized variations in cross-sectional dimensions, creating regions of different stiffness. This allows the spring to adapt to local conditions such as riser diameter variations and bending strains while maintaining a relatively simple overall structure that can still be manufactured using conventional processes.
3Force
If the spring stiffness is increased to prevent slipping, then the holding force improves, but the pressure distribution becomes uneven causing potential collapse
Solution Approach 1:
The spring design implements local quality by varying the cross-sectional dimensions along its length. The ends have increased stiffness (larger cross-section) to provide strong holding force and prevent slipping, while the center has reduced stiffness (smaller cross-section) to allow conformation to riser shape variations and distribute pressure evenly, thus preventing collapse.
Solution Approach 2:
The spring exhibits asymmetric stiffness distribution along its length, with stiffer regions at the ends and more flexible regions in the center. This asymmetric design optimizes the balance between holding force and pressure distribution, addressing the contradiction between these two requirements.
4Reliability
If the spring stiffness is decreased to improve pressure distribution, then the uniformity improves, but the holding force becomes insufficient causing slip
Solution Approach 1:
The spring incorporates local quality variations where the cross-sectional dimensions are optimized for different functions at different locations. The stiffer ends provide adequate holding force to prevent slipping, while the more flexible center region ensures uniform pressure distribution by accommodating riser diameter variations and bending strains.
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 spring design ensures uniform pressure distribution around the tubular member, preventing collapse and maintaining the riser configuration by distributing loads more evenly, thus enhancing the performance of buoyancy modules under varying conditions.
Implementation Method 1
a spring for a clamp suitable for attachment to a tubular member, the spring comprising a resilient body having first and second ends and an internal surface adapted to seat within a clamp member and an external surface adapted to contact the outer surface of a tubular member
Data Source
AI summary
A spring (5;105;205;305;404;505) for a clamp suitable for attachment to a tubular member, the spring comprising a resilient body (6;106;206;306;406;506) having first and second ends (8;108;208;308;408;508) and an internal surface (7;107;207;307;407;507) adapted to seat within a clamp member and an external surface (9;109;209;309;409;509) adapted to contact the outer surface of a tubular member, the internal and external surfaces extending between the first and second ends and wherein the stiffness of the resilient body of the spring varies over the length of the body between the first and second ends.