Connector Locking Lance Shear Stress Distribution
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Solution Overview
Problem
Existing connectors experience high shear stress in the locking lance when a terminal fitting is pulled, leading to potential shear fracture due to concentrated stress on the projection during insertion and withdrawal.
Innovation Solution
A connector design featuring a cantilevered locking lance with a projection that is narrower than the locking hole, a guiding portion gradually reduced in width, and an inclined surface to distribute stress, reducing the likelihood of the body portion being caught by the locking hole's edges and dispersing shear force across a wider area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the locking lace is formed to be narrower than the opening width of the locking hole to enable smooth insertion, then the insertion process is facilitated, but a shear stress concentrates on the base end part of the projection when the terminal fitting is pulled rearward
Solution Approach 1:
The locking lance is divided into distinct functional segments: a narrow projection for insertion engagement, a widened body portion for stress distribution, and a guiding portion with gradual width reduction. This segmentation allows each part to fulfill its specific function while collectively resolving the stress concentration problem
Solution Approach 2:
Different portions of the locking lance are given different local properties: the projection is narrow for smooth passage through the locking hole, while the body portion is widened to distribute shear stress, and the guiding portion has a gradual transition. This local differentiation of properties resolves the contradiction between insertion ease and stress concentration
2Reliability
If the projection width is smaller than the locking hole width to avoid interference during insertion, then the terminal fitting can be inserted properly, but the base end part of the projection becomes a stress concentration point when pulled
Solution Approach 1:
The locking lance transitions from a two-dimensional narrow projection to a three-dimensional widened body portion, adding a dimension of width increase toward the rear. This dimensional change allows the structure to engage smoothly in the insertion direction while providing stress distribution capacity in the pulling direction
Solution Approach 2:
The locking lance combines different geometric characteristics (narrow projection, widened body, gradual transition) into a composite structure that integrates both smooth insertion capability and stress resistance, effectively resolving the contradiction between reliability of locking and strength against shear fracture
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 design effectively reduces shear stress in the locking lance during terminal fitting pull, preventing shear fracture by distributing the force across a larger area and ensuring reliable locking and disengagement.
Implementation Method 1
the locking lace is resiliently displaced due to the interference of the terminal fitting with the projection. When the terminal fitting is inserted to a proper position, the locking lace resiliently returns
Implementation Method 2
a part of the body portion connected to the projection is formed with a guiding portion gradually reduced in width toward the projection... distributing the force across a larger area and ensuring reliable locking and disengagement
Data Source
AI summary
A connector includes a housing including a terminal accommodation chamber, a terminal fitting including a locking hole and to be inserted into the terminal accommodation chamber from behind the housing, and a locking lance for retaining the terminal fitting inserted into the terminal accommodation chamber. The locking lance is cantilevered forward and includes a body portion resiliently displaceable in a direction intersecting an insertion direction of the terminal fitting and a projection projecting from the body portion toward the terminal fitting and configured to enter the locking hole when the terminal fitting is inserted into the terminal accommodation chamber. A width of the projection is smaller than that of the locking hole. A maximum width of the body portion is larger than the width of the projection. A part of the body portion connected to the projection is formed with a guiding portion gradually reduced in width toward the projection.