Unidirectional Composite Modal Analysis for Stiffness Change Prediction

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Solution Overview

Problem

Existing methods fail to accurately examine how modal parameters change with structural stiffness reinforcement in unidirectional composite materials, particularly carbon-based composites, due to their anisotropic nature, and cannot predict dynamic behavior without physical testing.

Innovation Solution

A method and device that analyze mode changes in unidirectional composite materials by applying a physical force, sensing vibrations, performing modal analysis, and calculating modified mode shape vectors and assurance criteria to compensate for structural stiffness changes, allowing prediction of dynamic behavior without physical testing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If modal analysis is performed on unidirectional composite materials with structural stiffness reinforcement, then dynamic behavior can be predicted, but the anisotropic nature causes mode shape changes that complicate the analysis

Engineering Contradiction:

Improvemodal parameter measurement accuracyVSAvoidanalysis complexity due to anisotropy

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent transforms the mode shape vector by applying a transformation matrix that accounts for the structural stiffness reinforcement direction. This parameter transformation converts the complex anisotropic mode shapes into a standardized coordinate system, enabling accurate modal parameter measurement without being affected by the material's anisotropic nature.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a transformation matrix as an intermediary between the measured mode shapes and the modal assurance criterion calculation. This intermediary element accounts for the reinforcement direction and transforms the mode shapes into a common reference frame, simplifying the comparison and analysis process.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If physical specimens are fabricated and tested to obtain accurate dynamic behavior data, then reliable modal parameters are obtained, but time and resource consumption increase

Engineering Contradiction:

Improvedynamic behavior prediction reliabilityVSAvoidspecimen fabrication and testing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent performs preliminary transformation of mode shape vectors using a transformation matrix that incorporates the reinforcement direction information before calculating the modal assurance criterion. This preliminary action prepares the data in advance, enabling accurate dynamic behavior prediction without requiring physical specimen fabrication and testing.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses measured vibration data from simple tests to create transformed mode shape vectors that represent the dynamic behavior of the reinforced composite structure. Instead of fabricating multiple specimens for different reinforcement directions, the method copies and transforms the mode shape information mathematically to predict behavior for various reinforcement scenarios.

Inventive Principle:

Principle #26Copying

3Productivity

If mode shape vectors are directly used for modal assurance criterion calculation, then the calculation is simple, but shape information changes due to structural stiffness reinforcement cause inaccurate results

Engineering Contradiction:

Improvecalculation efficiencyVSAvoidmodal parameter accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent applies a parameter transformation to the mode shape vectors by multiplying them with a transformation matrix that accounts for the reinforcement direction. This transformation changes the parameter representation of the mode shapes while preserving the essential dynamic characteristics, enabling both accurate and efficient modal assurance criterion calculation.

Inventive Principle:

Principle #35Parameter changes

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

Effectively examines modal parameter changes and minimizes shape information changes, enabling accurate prediction of dynamic behavior in unidirectional composite materials with reinforced structural stiffness, even without fabricating specimens.

Implementation Method 1

sensing a vibration signal generated by the physical force at at least one sensed position of the specimen

Methodology Applied

Scientific EffectVibration: Vibration

Data Source

PatentUS12571772B2Apparatus and method for analyzing mode change of unidirectional composite materials

Publication Date: 2026.03.10 PUKYONG NAT UNIV IND ACADEMIC COOPERATION FOUND

AI summary

A method for analyzing change in a mode of a unidirectional composite material includes applying a physical force of a predetermined pattern onto a unidirectional composite material specimen; sensing a vibration signal generated by the physical force at at least one sensed position thereof; performing modal analysis of a frequency response at a corresponding measurement location, based on the physical force applied to the specimen and the vibration signal measured at the sensed position of the specimen, and calculating at least one mode shape vector of the specimen based on the modal analysis result; compensating the calculated mode shape vector based on a distance between a normal line passing through a center of the specimen and the sensed position, thereby calculating a modified mode shape vector; and calculating a first modal assurance criterion (MAC) of the specimen based on the modified mode shape vector.