Lorry Subframe Shear-Yielding Connectors for Bending Stress Distribution
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Solution Overview
Problem
Existing lorry designs face challenges in distributing bending moments between the subframe and chassis, leading to potentially high stresses on the subframe and loss of wheel contact with the ground due to stiffness when carrying heavy loads, especially on uneven terrain.
Innovation Solution
The implementation of shear-yielding connecting elements with elongated slide slots and sliding members, allowing longitudinal movement while maintaining vertical contact between the subframe and chassis, ensures efficient force transfer and stress distribution, preventing vertical separation and maintaining wheel contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the subframe is rigidly connected to the chassis, then the bending moments are properly distributed between subframe and chassis, but the vehicle becomes too stiff and wheels may lose contact with the ground on uneven terrain
Solution Approach 1:
The connecting elements are designed to change their mechanical behavior dynamically: under normal conditions they provide rigid connection for strength, but under high bending moments they allow controlled separation to maintain vehicle flexibility and wheel contact with the ground
2Ease of operation
If the subframe and chassis are allowed to separate vertically under high bending moments, then the vehicle remains flexible on uneven terrain, but the subframe takes up all bending moments causing excessively high stresses
Solution Approach 1:
The lower surfaces of the subframe and chassis are designed with contact capability that acts as a preliminary protective measure: when vertical separation occurs under high bending moments, the contact surfaces engage to prevent complete separation, ensuring the chassis continues to share the bending moment load and preventing excessive stresses in the subframe
3Strength
If shear-yielding connecting elements prevent vertical movement between subframe and chassis, then bending moments are properly distributed, but the connection becomes too rigid and wheels may lose ground contact
Solution Approach 1:
The connecting elements have different properties in different directions: they provide strong vertical connection to distribute bending moments while allowing longitudinal movement to maintain vehicle flexibility and wheel contact with the ground on uneven terrain
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
This configuration allows for effective stress distribution and prevents excessive stress on the subframe, ensuring the chassis contributes to bending moments while maintaining wheel contact on uneven terrain, enhancing the vehicle's stability and safety.
Implementation Method 1
A longitudinal planar contact surface is provided on a lower longitudinal edge of said sliding member, wherein this contact surface faces and is in sliding contact with a corresponding longitudinal planar contact surface on a lower longitudinal edge of the associated slide slot, to thereby allow the subframe to slide longitudinally in relation to the chassis and at the same time prevent a relative movement between the subframe and the chassis vertically
Data Source
Figure 1~3
Figure 4~6
Figure 7~8
AI summary
A lorry comprising a chassis (3) and a subframe (5) mounted to the chassis by means of shear-yielding connecting elements (20). Each such connecting element comprises an attachment plate (21'), which is rigidly fixed to the subframe and overlaps a part of a vertical and longitudinal side wall (14) of the chassis, wherein the attachment plate (21') is provided with at least one elongated slide slot (22) and an associated sliding member (23') received therein. The sliding member is fixed to the chassis by means of at least one bolt (24). A longitudinal planar contact surface (30) on a lower longitudinal edge of the sliding member is in sliding contact with a corresponding longitudinal planar contact surface (31) on a lower longitudinal edge of the associated slide slot, to thereby allow the subframe to slide longitudinally in relation to the chassis and at the same time prevent a relative movement between the subframe and the chassis vertically.