Bolt Assembly Shear Zone Protection via Locking Ring
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Solution Overview
Problem
Existing controlled shear bolt assemblies face issues with fragility during handling and installation, uneven torque distribution due to reduced threaded surface, and oversized tightening torques for small elements, leading to potential breakage and instability in shear zones.
Innovation Solution
A bolt assembly design featuring a bolt body with a threaded portion, shank, and a ring with a tab to ensure rotation locking, where the shear zone is protected by the ring and maintains a continuous thread, allowing consistent shearing torque regardless of installation depth and preventing damage during handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If grooves are made in the threaded portion of the bolt to create controlled shear zones, then the bolt can be sheared at controlled locations, but the threaded surface is reduced and the bolt becomes fragile
Solution Approach 1:
The bolt is segmented into distinct functional zones: a threaded portion with reduced diameter that serves as the controlled shear zone, and a shank portion with full threaded surface that provides structural strength. This segmentation allows the bolt to be sheared at a specific location while maintaining overall structural integrity during handling.
Solution Approach 2:
The shear zone functionality is extracted from the threaded portion and placed in a separate shank portion. The shank contains the controlled shear zones while the threaded portion maintains its full threaded surface for optimal force distribution. This extraction resolves the conflict between shear control and structural strength.
2Reliability
If grooves are made in the threaded portion to create multiple shear stages, then the number of engaged threads is maximized, but the threaded surface is reduced and force distribution is deteriorated
Solution Approach 1:
The bolt structure is segmented into a shank portion containing shear zones and a threaded portion with full threaded surface. This segmentation ensures that the threaded surface area is maximized for optimal force distribution while the shear zones are located in the separate shank portion.
Solution Approach 2:
The shear zones are extracted from the threaded portion and relocated to the shank portion. This allows the threaded portion to maintain its full threaded surface area for optimal force distribution, while the shank provides the controlled shear functionality.
3Adaptability or versatility
If the bolt is designed to break more easily at low installation depths, then small elements can be tightened, but the tightening torque becomes oversized for small elements leading to potential breakage
Solution Approach 1:
Different portions of the bolt have different mechanical properties: the shank portion has controlled shear zones designed to fail at specific torques, while the threaded portion has full threaded surface for optimal force distribution. This local quality differentiation allows the bolt to adapt to various installation depths without oversizing the tightening torque for small elements.
Data Source
AI summary
A bolt assembly has a bolt body which includes a threaded portion and a shank; a head; a ring; and a shear zone. The head is configured to transmit rotary motion to the threaded portion through the shank. The ring is disposed on the shank and has a ring thread and a tab configured to ensure continuity between the ring thread and the threaded portion. The shear zone joins the shank to the threaded portion and a complementary recess, disposed on the threaded portion, is engageable with the tab to ensure rotation locking of the ring in relation to the threaded portion.