Variable-Stiffness Mounting for Rotating Machinery Overloads
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Solution Overview
Problem
Existing mounting systems for large rotating machines in the oil and gas industry face challenges with stability and misalignment due to environmental loads, particularly in offshore applications, where three-point isostatic systems can be prone to overload and require oversized supporting members, limiting the size and weight of machinery that can be supported.
Innovation Solution
A combined mounting system featuring main supporting members for normal loads and auxiliary members with variable stiffness that become active under overloads, allowing the system to transition from an isostatic to a hyperstatic configuration, distributing excessive loads and maintaining alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a three-point isostatic mounting system is used, then the system allows thermal growth and accommodates deck motion, but the supporting members become prone to overload and require oversized dimensions
Solution Approach 1:
The mounting system is segmented into multiple supporting members (more than three) distributed across the base frame. This segmentation distributes the load across multiple points, preventing any single supporting member from becoming overloaded while maintaining the ability to accommodate thermal growth and deck motion through the collective flexibility of the distributed system.
Solution Approach 2:
The system employs dynamic characteristics in the supporting members, allowing them to flex and adapt to deck motion and thermal expansion. The supporting members are designed with appropriate stiffness characteristics that enable them to accommodate movements while still providing adequate support, transitioning from a static rigid system to a dynamic adaptive system.
2Force
If main supporting members are oversized to handle overloads, then the system can support heavier loads, but the size and weight of the supporting structure increases
Solution Approach 1:
By segmenting the support function across multiple smaller supporting members rather than using fewer oversized members, the system achieves the same or greater load handling capacity with reduced individual member sizes. The collective arrangement of multiple members provides redundancy and distributed load bearing, allowing the use of lighter, more compact supporting structures.
Solution Approach 2:
The system changes the parameter of supporting member quantity from three to multiple, which fundamentally alters the load distribution characteristics. This parameter change allows the use of smaller, lighter members while maintaining or improving overall load capacity through the combined effect of multiple supporting points working together.
3Stability of the object's composition
If a multi-point hyperstatic mounting system is used, then the system provides robust support, but it causes misalignment when mounting points move out of plane due to vessel deck twisting
Solution Approach 1:
The system employs dynamic characteristics in the supporting members, allowing them to flex and adapt to deck motion. This dynamic behavior enables the supporting members to maintain proper alignment of the rotating machines even when the vessel deck twists, as the members can adjust their positions within acceptable tolerances while still providing stable support.
Solution Approach 2:
The system changes from a three-point to a multi-point configuration, which fundamentally alters the geometric constraints. With more than three supporting points distributed across the base frame, the system creates a geometry that is more tolerant of out-of-plane movements, maintaining alignment precision even when individual mounting points experience deck-induced displacements.
Data Source
AI summary
A mounting system for supporting rotating machinery is described. The system comprises a base frame having an upper side for mounting the rotating machinery, and a lower side. A set of main supporting members are arranged according to a triangular arrangement and forming a three-point mounting arrangement defining a mounting plane. Moreover, a set of auxiliary supporting members, having a variable stiffness in at least one direction, are provided and are configured and arranged such as to increase the stiffness thereof when the base frame is subject to an overload, thus reducing load on the main supporting members.