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.

Nonlinear Membrane Direct and Inverse FEM Analysis

2014 ◽  
Author(s):  
Mattia Alioli ◽  
Pierangelo Masarati ◽  
Marco Morandini ◽  
Trenton Carpenter ◽  
Roberto Albertani
Keyword(s):  
Three Dimensional ◽  
Fem Analysis ◽  
Solution Procedure ◽  
General Purpose ◽  
Inverse Solution ◽  
Surface Strain ◽  
Image Correlation ◽  
Direct Solution ◽  
Strain Measurements ◽  
Solution Approach

The analysis of thin structural components integrated within a general-purpose multibody system dynamics formulation is presented. An original inverse finite element solution procedure is developed to reconstruct the deformed shape of a membrane from in-plane membrane strain measurements, and eventually indirectly estimate the distributed loads. A direct solution approach is used in co-simulation with fluid-dynamics solvers to predict the configuration of the system under static and unsteady loads. Numerical validation of the inverse solution is performed considering the results of direct solution analysis. The direct and inverse solutions are validated considering experimental displacement and strain measurements obtained using digital image correlation. Moving Least Squares are used to smooth and remap measurements as needed by the inverse solution meshing. Utilizing surface strain measurements from strain sensors, the methodology enables the accurate computation of the three-dimensional displacement field.

Full-field strain measurements at the micro-scale in fiber-reinforced composites using digital image correlation

2016 ◽  
Vol 140 ◽  
pp. 192-201 ◽  
Author(s):  
Mahoor Mehdikhani ◽  
Mohammadali Aravand ◽  
Baris Sabuncuoglu ◽  
Michaël G. Callens ◽  
Stepan V. Lomov ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Image Correlation ◽  
Fiber Reinforced Composites ◽  
Field Strain ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Full Field ◽  
Strain Measurements ◽  
Micro Scale

scholarly journals A Probabilistic Approach with Built-in Uncertainty Quantification for the Calibration of a Superelastic Constitutive Model from Full-field Strain Data

2019 ◽  
Author(s):  
Harshad M Paranjape ◽  
Kenneth I. Aycock ◽  
Craig Bonsignore ◽  
Jason D. Weaver ◽  
Brent A. Craven ◽  
...  
Keyword(s):  
Machine Learning ◽  
Bayesian Inference ◽  
Constitutive Model ◽  
Probabilistic Approach ◽  
Surface Strain ◽  
Image Correlation ◽  
Full Field ◽  
Material Parameters ◽  
Superelastic Deformation ◽  
Calibration Approach

We implement an approach using Bayesian inference and machine learning to calibrate the material parameters of a constitutive model for the superelastic deformation of NiTi shape memory alloy. We use a diamond-shaped specimen geometry that is suited to calibrate both tensile and compressive material parameters from a single test. We adopt the Bayesian inference calibration scheme to take full-field surface strain measurements obtained using digital image correlation together with global load data as an input for calibration. The calibration is performed by comparing these two experimental quantities of interest with the corresponding results from a simulation library built with the superelastic forward finite element model. We present a machine learning based approach to enrich the simulation library using a surrogate model. This improves the calibration accuracy to the extent permitted by the accuracy of the underlying material model and also improves the computational efficiency. We demonstrate, verify, and partially validate the calibration results through various examples. We also demonstrate how the uncertainty in the calibrated superelastic material parameters can propagate to a subsequent simulation of fatigue loading. This approach is versatile and can be used to calibrate other models of superelastic deformation from data obtained using various modalities. This probabilistic calibration approach can become an integral part of a framework to assess and communicate the credibility of simulations performed in the design of superelastic NiTi articles such as medical devices. The knowledge obtained from this calibration approach is most effective when the limitations of the underlying model and the suitability of the training data used to calibrate the model are understood and communicated.

scholarly journals Bio-Inspired 3D Infill Patterns for Additive Manufacturing and Structural Applications

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 499 ◽  
Author(s):  
Jan Podroužek ◽  
Marco Marcon ◽  
Krešimir Ninčević ◽  
Roman Wan-Wendner
Keyword(s):  
Additive Manufacturing ◽  
Mechanical Performance ◽  
Peak Load ◽  
Fem Analysis ◽  
Material Model ◽  
Surface Strain ◽  
Image Correlation ◽  
Nonlinear Material ◽  
Full Field ◽  
Structural Applications

The aim of this paper is to introduce and characterize, both experimentally and numerically, three classes of non-traditional 3D infill patterns at three scales as an alternative to classical 2D infill patterns in the context of additive manufacturing and structural applications. The investigated 3D infill patterns are biologically inspired and include Gyroid, Schwarz D and Schwarz P. Their selection was based on their beneficial mechanical properties, such as double curvature. They are not only known from nature but also emerge from numerical topology optimization. A classical 2D hexagonal pattern has been used as a reference. The mechanical performance of 14 cylindrical specimens in compression is quantitatively related to stiffness, peak load and weight. Digital image correlation provides accurate full-field deformation measurements and insights into periodic features of the surface strain field. The associated variability, which is inherent to the production and testing process, has been evaluated for 3 identical Gyroid specimens. The nonlinear material model for the preliminary FEM analysis is based on tensile test specimens with 3 different slicing strategies. The 3D infill patterns are generally useful when the extrusion orientation cannot be aligned with the build orientation and the principal stress field, i.e., in case of generative design, such as the presented branching structure, or any complex shape and boundary condition.

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.

Stereomicroscopic optical method for the assessment of load transfer patterns across the wood-adhesive bond interphase

Holzforschung ◽  
2015 ◽  
Vol 69 (5) ◽  
pp. 653-660 ◽  
Author(s):  
Matthew Schwarzkopf ◽  
Lech Muszyński
Keyword(s):  
Mechanical Properties ◽  
Load Transfer ◽  
Mechanical Performance ◽  
Adhesive Bond ◽  
Wood Adhesive ◽  
Surface Strain ◽  
Image Correlation ◽  
Optical Measurements ◽  
Experimental Methodology ◽  
Full Field

Abstract The mechanical performance of wood-based composites is determined by the mechanical properties of their individual components and the effective load transfer between these components. In laminated wood composites, this load transfer is facilitated by the adhesive bond. The experimental methodology developed in this study measures and analyzes the full-field deformation and strain distributions across the loaded wood-adhesive interphase at a micromechanical level. Optical measurements were performed based on the principles of digital image correlation by a stereomicroscopic camera system. This system allows the monitoring of in-plane deformations as well as out-of-plane displacements, providing full-field 3D surface strain maps across the adhesive bond. These measurements can be used to improve the understanding of the load transfer between the adherents and the contribution of the adhesive to the mechanical properties of the bulk composite and serve as a quantitative input for numerical modeling and simulations aimed at the improvement of the products.

Validation of Digital Image Correlation Techniques for Strain Measurement in Biomechanical Test Models

2013 ◽  
Author(s):  
Renee D. Rogge ◽  
Scott R. Small ◽  
Derek B. Archer ◽  
Michael E. Berend ◽  
Merrill A. Ritter
Keyword(s):  
Aluminum Alloy ◽  
Digital Image Correlation ◽  
Polyurethane Foam ◽  
Digital Image ◽  
Measurement Techniques ◽  
Image Correlation ◽  
Principal Strain ◽  
Strain Gages ◽  
Full Field ◽  
Strain Measurements

Many previous biomechanical studies of bone and bone substitutes have estimated strains in these materials using strain gages. The purpose of this study was to compare digital image correlation (DIC) strain measurements to those obtained from strain gages in order to assess the applicability of DIC technology to common biomechanical testing scenarios. Compression and bending tests were conducted on aluminum alloy, polyurethane foam, and laminated polyurethane foam specimens. Results showed no significant differences in the principal strain values (or the variances) between strain gage and DIC measurements on the aluminum alloy and laminated polyurethane foam specimens. There were significance differences between the principal strain measurements of the non-laminated polyurethane foam specimens, but the deviation from the theoretical results was similar for both measurement techniques. In summary, DIC techniques provide similar results to those obtained from strain gages and also provide full field strain results.

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