scholarly journals Full-Field Strain Reconstruction Using Uniaxial Strain Measurements: Application to Damage Detection

2021 ◽  
Vol 11 (4) ◽  
pp. 1681
Author(s):  
Rinto Roy ◽  
Marco Gherlone ◽  
Cecilia Surace ◽  
Alexander Tessler
Keyword(s):  
Uniaxial Strain ◽  
Surface Strain ◽  
Internal Crack ◽  
Full Field ◽  
Strain Measurements ◽  
Reconstruction Performance ◽  
Strain Smoothing ◽  
Strain Data ◽  
Position And Orientation ◽  
Displacement Reconstruction

This work investigates the inverse problem of reconstructing the continuous displacement field of a structure using a spatially distributed set of discrete uniaxial strain data. The proposed technique is based on the inverse Finite Element Method (iFEM), which has been demonstrated to be suitable for full-field displacement, and subsequently strain, reconstruction in beam and plate structures using discrete or continuous surface strain measurements. The iFEM uses a variationally based approach to displacement reconstruction, where an error functional is discretized using a set of finite elements. The effects of position and orientation of uniaxial strain measurements on the iFEM results are investigated, and the use of certain strain smoothing strategies for improving reconstruction accuracy is discussed. Reconstruction performance using uniaxial strain data is examined numerically using the problem of a thin plate with an internal crack. The results obtained highlight that strain field reconstruction using the proposed strategy can provide useful information regarding the presence, position, and orientation of damage on the plate.

Delamination Identification in Stiffened Composite Panels Using Surface Strain Data

2017 ◽  
Vol 754 ◽  
pp. 379-382
Author(s):  
George Lampeas ◽  
Christos Katsikeros ◽  
Konstantinos Fotopoulos
Keyword(s):  
Strain Field ◽  
Structural Integrity ◽  
Decomposition Methods ◽  
Surface Strain ◽  
Composite Panel ◽  
Data Decomposition ◽  
Full Field ◽  
Stiffened Composite Panels ◽  
Strain Data ◽  
Efficient Processing

The structural integrity of a composite structure can be greatly compromised by damage inside the component. Invisible damage, e.g. caused by low-speed impact, can significantly reduces composite components capability to efficiently carry loads. In the present study, an innovative approach of strain-based delamination identification and localization is investigated, based on the efficient processing of full-field surface strain measurements. Surface strain data, potentially derived by full-field optical methodologies are used in the assessment of the delamination pattern, through strain field perturbations caused due to damage evolution. Relations between delamination damage and surface strain field disturbances are established by exploiting data decomposition methods using Zernike polynomial moments. The methodology is successfully demonstrated in the case of a stiffened composite panel.

Membrane Shape and Transverse Load Reconstruction Using Inverse FEM

2015 ◽  
Author(s):  
Mattia Alioli ◽  
Pierangelo Masarati ◽  
Marco Morandini ◽  
Trenton Carpenter ◽  
N. Brent Osterberg ◽  
...  
Keyword(s):  
Broad Class ◽  
Direct Analysis ◽  
General Purpose ◽  
Surface Strain ◽  
Image Correlation ◽  
Transverse Load ◽  
Full Field ◽  
Strain Measurements ◽  
Load Distributions ◽  
Tightly Coupled

Thin structural components characterize a broad class of Micro-Aerial Vehicles (MAV). This work presents an original approach for the determination of transverse load distribution based on distributed strain measurements. A variational formulation is developed for the inverse problem of the reconstruction of full-field structural displacement of membrane wings subjected to static and unsteady loads. Surface strain measurements are estimated from Digital Image Correlation (DIC). Moving Least Squares are used to smooth and remap measurements as needed by the inverse solution meshing, and to map the structural and fluid interface kinematics and loads during the fluid-structure co-simulation. The inverse analysis is verified by reconstructing the deformed solution obtained with an analogous direct formulation, based on nonlinear membrane structural analysis implemented in a general-purpose multibody solver and tightly coupled in co-simulation with a CFD solver. The direct analysis is performed on a different mesh and subsequently re-sampled. Both the direct and the inverse analyses are validated by comparing the direct predictions and the reconstructed deformations with experimental data for prestressed rectangular membranes subjected to static and unsteady loads. The reconstructed load distributions are compared with the corresponding ones obtained using the direct analysis.

Modeling of Contact Patch in Dual-Chamber Pneumatic Tires

2018 ◽  
Vol 46 (2) ◽  
pp. 78-92 ◽  
Author(s):  
A. I. Kubba ◽  
G. J. Hall ◽  
S. Varghese ◽  
O. A. Olatunbosun ◽  
C. J. Anthony
Keyword(s):  
Strain Sensors ◽  
Surface Strain ◽  
Wireless Data ◽  
Data Logger ◽  
Dual Chamber ◽  
Piezoelectric Polymer ◽  
Pure Rolling ◽  
Piezoelectric Elements ◽  
Strain Data ◽  
Deformation Patterns

ABSTRACT This study presents an investigation of the inner tire surface strain measurement by using piezoelectric polymer transducers adhered on the inner liner of the tire, acting as strain sensors in both conventional and dual-chamber tires. The piezoelectric elements generate electrical charges when strain is applied. The inner liner tire strain can be found from the generated charge. A wireless data logger was employed to measure and transmit the measured signals from the piezoelectric elements to a PC to store and display the readout signals in real time. The strain data can be used as a monitoring system to recognize tire-loading conditions (e.g., traction, braking, and cornering) in smart tire technology. Finite element simulations, using ABAQUS, were employed to estimate tire deformation patterns in both conventional and dual-chamber tires for pure rolling and steady-state cornering conditions for different inflation pressures to simulate on-road and off-road riding tire performances and to compare with the experimental results obtained from both the piezoelectric transducers and tire test rig.

scholarly journals Fatigue Cracking Resistance of Engineered Cementitious Composites (ECC) under Working Condition of Orthotropic Steel Bridge Decks Pavement

2019 ◽  
Vol 9 (17) ◽  
pp. 3577 ◽  
Author(s):  
Yanjing Zhao ◽  
Jiwang Jiang ◽  
Fujian Ni ◽  
Lan Zhou
Keyword(s):  
Digital Image ◽  
Working Condition ◽  
Fatigue Cracking ◽  
Surface Strain ◽  
Internal Crack ◽  
Cementitious Composites ◽  
Cracking Resistance ◽  
Engineered Cementitious Composites ◽  
Crack Distribution ◽  
Scb Test

In order to investigate the fatigue cracking resistance of engineered cementitious composites (ECC) used in in total life pavement, the semi-circular bending (SCB) test and improved three-point bending fatigue test (ITBF) were utilized in this study. The digital image correlation (DIC) method was also utilized to track the surface strain fields of specimens during the SCB test. X-ray computed tomography (CT) and digital image processing (DIP) technologies were applied to measure the internal-crack distribution of the ITBF specimen. The results of the SCB test showed that the fatigue cracking damage process of ECC can be divided into three stages and that the cracking stable propagating stages occupied the main part, which indicates that ECC has excellent ductility and toughness and could work very well with existing cracks. The ITBF results showed that the fatigue cracking resistance of ECC was better than epoxy asphalt concrete (EAC). In addition, the internal-crack distribution along the depth direction of the ITBF specimen could be presented well by the image pixel statistical (IPS) method based on CT scanning of image slices. It could be found that multiple cracks propagate simultaneously in ECC, instead of a single crack, under the OSBD pavement working condition.

Hole-Drilling Residual Stress Profiling With Automated Smoothing

2007 ◽  
Vol 129 (3) ◽  
pp. 440-445 ◽  
Author(s):  
Gary S. Schajer
Keyword(s):  
Residual Stress ◽  
A Priori ◽  
Hole Drilling ◽  
Simple Method ◽  
Strain Measurements ◽  
Stress Solution ◽  
Strain Data ◽  
Data Content ◽  
Small Increments ◽  
Priori Information

An effective procedure is presented that allows stable hole-drilling residual stress calculations using strain data from measurements taken at many small increments of hole depth. This use of many strain measurements is desirable because it improves the data content of the calculation, and the statistical reliability of the residual stress results. The use of Tikhonov regularization to reduce the noise sensitivity that is characteristic of a fine-increment calculation is described. This mathematical procedure is combined with the Morozov criterion to identify the optimal amount of regularization that balances the competing tendencies of noise reduction and stress solution distortion. A simple method is described to estimate the standard error in the strain measurements so that the optimal regularization can be chosen automatically. The possible use of a priori information about the trend of the expected solution is also discussed as a further means of improving the stress solution. The application of the described method is demonstrated with some experimental measurements, and realistic results are obtained.

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