Composite Leaf Spring Durability Monitoring via Embedded Current Sensing

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Solution Overview

Problem

Composite leaf springs used in two-shaft suspension systems for large trucks deteriorate through delamination, making it difficult for drivers to visually or audibly recognize the need for replacement, leading to frequent accidents due to undetected damage.

Innovation Solution

A device with current transmitters and receivers connected to the composite leaf spring, a controller to compare applied and detected currents, and an informing device to alert the driver through auditory and visual signals about the spring's state, indicating the need for replacement based on current differences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If a composite leaf spring is used instead of a steel plate leaf spring, then weight is reduced and fuel efficiency is improved, but durability monitoring becomes difficult and accident risk increases

Engineering Contradiction:

Improveweight of leaf springVSAvoiddurability monitoring capability

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The patent replaces the mechanical/visual monitoring system with an electrical sensing system. Electrical leads are embedded within the composite leaf spring layers, and a controller monitors current flow to detect delamination. This substitution enables effective monitoring of the composite material's integrity without relying on visual inspection or auditory cues that work for steel plate springs.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces electrical leads as intermediary elements embedded within the composite leaf spring structure. These leads serve as mediators that transmit electrical current through the spring layers, allowing the controller to detect changes in current flow that indicate delamination or damage to the composite material.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Use of energy by moving object

If a composite leaf spring is used instead of a steel plate leaf spring, then fuel efficiency is improved, but visual and auditory detection of damage becomes impossible

Engineering Contradiction:

Improvefuel efficiencyVSAvoiddamage detection capability

Core Design Contradiction:

Use of energy by moving objectVSDifficulty of detecting and measuring

Solution Approach 1:

The patent replaces visual and auditory detection methods with an electrical sensing system. Instead of relying on drivers to see cracks or hear noises, the system uses embedded electrical leads to continuously monitor current flow through the composite spring, automatically detecting delamination and damage through changes in electrical properties.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements a feedback system where the controller continuously monitors current flow through the embedded leads and provides real-time information about the leaf spring's condition. The system compares expected current flow with actual measurements and alerts the driver when damage is detected, creating a closed-loop monitoring system that provides continuous feedback on structural integrity.

Inventive Principle:

Principle #23Feedback

3Reliability

If multiple steel plates are used to form the leaf spring, then durability is improved for a given price, but weight increases and fuel efficiency decreases

Engineering Contradiction:

Improvedurability of leaf springVSAvoidweight of leaf spring

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent employs composite materials consisting of multiple layers of composite material (such as carbon fiber reinforced polymer) stacked and bonded together to form the leaf spring. This composite construction achieves the necessary durability and structural integrity while significantly reducing weight compared to traditional steel plate construction, thereby improving fuel efficiency without sacrificing reliability.

Inventive Principle:

Principle #40Composite materials

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 device effectively monitors the composite leaf spring's durability and alerts the driver to potential fractures, preventing accidents by providing timely information on the need for replacement.

Implementation Method 1

a current transmitter and a current receiver provided at respective opposite ends of the composite leaf spring

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS10564054B2Device for indicating replacement time of composite leaf spring

Publication Date: 2020.02.18 HYUNDAI MOTOR CO LTD

AI summary

A device for indicating a replacement time of a composite leaf spring constantly monitors durability of the composite leaf spring, which is formed by mixing unidirectional glass fiber and epoxy resin, and informs a driver of an appropriate replacement time of the composite leaf spring based on the monitoring result.