Plastic-Deforming Strain Sensor for Fragile Part Damage Warning

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Solution Overview

Problem

Current strain sensors are ineffective in detecting early warning signs of catastrophic failure in fragile parts, particularly those made of ceramic or glass, due to rapid crack propagation and difficulty in accessing or monitoring unusual shapes, and they require complex investigative techniques like radiography.

Innovation Solution

A strain sensor configured to deform plastically under minimum damage stress, retaining a residual deformation to indicate stress exposure, allowing discontinuous monitoring and long lifespan without continuous measurement, with a threshold stress set below the minimum damage stress to avoid breaking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional strain sensors are used to monitor fragile parts, then continuous measurement capability is provided, but the sensors are ineffective at identifying early warning signs of catastrophic failure and require complex investigative techniques

Engineering Contradiction:
Improveeffectiveness in detecting early warning signs of catastrophic failureVSAvoidcomplexity of monitoring system
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the material parameter of the strain sensor from elastic to plastic behavior. The strain sensor is designed to undergo plastic deformation at a threshold stress level that corresponds to the minimum damage stress of the fragile part. This parameter change allows the sensor to permanently record damage events through residual deformation, providing reliable detection of early warning signs without requiring continuous monitoring or complex investigative techniques.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If continuous measurement is performed to monitor fragile parts, then real-time condition assessment is achieved, but monitoring becomes complex and requires continuous energy input

Engineering Contradiction:
Improvecondition assessment accuracyVSAvoidenergy consumption for continuous monitoring
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The strain sensor is pre-configured with a specific threshold stress level that corresponds to the minimum damage stress of the fragile part. This preliminary setting allows the sensor to automatically trigger plastic deformation and permanent recording when the threshold is reached, eliminating the need for continuous energy input or active monitoring systems while maintaining precise condition assessment capability.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If the strain sensor threshold stress is set close to the minimum damage stress, then early warning detection is improved, but the risk of sensor breakage before part damage increases

Engineering Contradiction:
Improveearly warning detection capabilityVSAvoidsensor durability
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent introduces an intermediary relationship between the strain sensor and the fragile part through a carefully designed threshold stress level. This threshold acts as a mediator that is set at or slightly below the minimum damage stress of the fragile part, ensuring the sensor undergoes plastic deformation to record damage events while the fragile part remains intact. The intermediary threshold allows early warning detection without compromising sensor durability.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 strain sensor effectively records and assesses damage to fragile parts by plastic deformation, providing a simple and reliable method to monitor their condition over time, even in challenging environments.

Implementation Method 1

the strain sensor deforms elastically when the stress applied to the fragile part is low and far from the minimum damage stress... When the stress is removed, the device returns to its initial geometry

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

the strain sensor deforms plastically under the effect of at least one stress applied to the brittle part and leading to damage to the brittle part... the strain sensor retains a residual deformation that allows identification of the fact that the fragile part was subjected to said stress

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Data Source

PatentEP4073480B1Device for controlling a fragile part
Publication Date: 2026.04.15 SAINT GOBAIN CENT DE RES & DEVS & DETUD EUROEN
  • EP4073480B1 patent drawingFigure 1~2
  • EP4073480B1 patent drawingFigure 3~4

AI summary

The invention relates to a device comprising: - a fragile part (10) made of a material having a plastic deformation domain under load before breaking and an elastic deformation domain, the plastic deformation domain representing less than 1% of the elastic deformation domain, and - a deformation sensor (2) attached to the fragile part and configured to plastically deform under the effect of at least one stress applied to the fragile part and leading to a damage of the fragile part.