Tapered Dog Configuration for Shear Load Sharing in Subterranean Tool Housing
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Solution Overview
Problem
Existing lock mandrel designs face challenges in distributing shear loads effectively, leading to stress on the housing between dog windows, which can result in reduced strength and increased stress concentrations due to the tradeoff between dog width and housing wall thickness.
Innovation Solution
The implementation of multiple rows of locking dogs with axial flexibility between rows, combined with extensions that transfer loads from the housing to the dogs and surrounding profile, allowing for load sharing and reduced stress on individual contact points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the dogs are made wider to hold more shear load, then the shear load capacity is improved, but the housing wall thickness is reduced which worsens the structural strength
Solution Approach 1:
The housing is segmented into multiple sections (first section, second section, third section) with varying wall thicknesses. The first section has greater wall thickness to accommodate wider dogs for higher shear load capacity, while the second and third sections have reduced wall thickness to minimize material usage and weight, resolving the contradiction between shear load capacity and structural strength.
Solution Approach 2:
Different sections of the housing have different wall thicknesses tailored to their specific functional requirements. The first section near the dogs has thicker walls for strength and load bearing, while other sections have thinner walls, creating local quality variations that optimize both shear load capacity and overall structural efficiency.
2Force
If the housing wall thickness is reduced to accommodate wider dogs, then the shear load capacity is improved, but the stress concentration in the housing increases
Solution Approach 1:
The housing is divided into segments with different wall thicknesses, allowing the first section to bear the brunt of stress concentrations near the dogs while other sections use less material, thereby managing stress distribution effectively.
Solution Approach 2:
The housing utilizes composite construction with varying wall thicknesses in different sections, creating a composite structure that optimizes stress distribution. The thicker first section acts as a stress-bearing element while thinner sections reduce overall mass, resolving the stress concentration issue.
Data Source
AI summary
A plurality of rows of locking dogs are provided with housing flexibility between rows to allow them to share a shear loading while leaving enough structural integrity in the housing to define the windows through which the dogs emerge. The dogs can also have extensions with a surface that grippingly engages the housing adjacent the window on extension of the dogs such that loads can transfer from the housing into the extension and into the profile in which the dog is disposed rather than passing the shear stress through the window edge into the dog that is in the profile. The dog configuration can also share the load on multiple contact surfaces of the housing to reduce stress at each contact location.