scholarly journals Material Parameter Identification for Acoustic Simulation of Additively Manufactured Structures

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 168
Author(s):  
Sebastian Rothe ◽  
Christopher Blech ◽  
Hagen Watschke ◽  
Thomas Vietor ◽  
Sabine C. Langer
Keyword(s):  
Krylov Subspace ◽  
Mechanical Impedance ◽  
Element Model ◽  
Material Parameter Identification ◽  
Material Parameters ◽  
Material Deposition ◽  
Mechanical Models ◽  
Acoustic Black Holes ◽  
Full Design ◽  
Design Freedom

One possibility in order to manufacture products with very few restrictions in design freedom is additive manufacturing. For advanced acoustic design measures like Acoustic Black Holes (ABH), the layer-wise material deposition allows the continuous alignment of the mechanical impedance by different filling patterns and degrees of filling. In order to explore the full design potential, mechanical models are indispensable. In dependency on process parameters, the resulting homogenized material parameters vary. In previous investigations, especially for ABH structures, a dependency of the material parameters on the structure’s thickness can be observed. In this contribution, beams of different thicknesses are investigated experimentally and numerically in order to identify the material parameters in dependency on the frequency and the thickness. The focused material is polyactic acid (PLA). A parameter fitting is conducted by use of a 3D finite element model and it’s reduced version in a Krylov subspace. The results yield homogenized material parameters for the PLA stack as a function of frequency and thickness. An increasing Young’s modulus with increasing frequency and increasing thickness is observed. This observed effect has considerable influence and has not been considered so far. With the received parameters, more reliable results can be obtained.

scholarly journals Biaxial estimation of biomechanical constitutive parameters of passive porcine sclera soft tissue

2021 ◽  
Author(s):  
Zwelihle Ndlovu ◽  
Dawood Desai ◽  
Thanyani Pandelani ◽  
Harry Ngwangwa ◽  
Fulufhelo Nemavhola
Keyword(s):  
Finite Element ◽  
Soft Tissue ◽  
Finite Element Model ◽  
Test Data ◽  
Element Model ◽  
Finite Element Models ◽  
Anisotropic Model ◽  
Material Models ◽  
Material Parameters ◽  
Constitutive Parameters

This study assesses the modelling capabilities of four constitutive hyperplastic material models to fit the experimental data of the porcine sclera soft tissue. It further estimates the material parameters and discusses their applicability to a finite element model by examining the statistical dispersion measured through the standard deviation. Fifteen sclera tissues were harvested from porcine’ slaughtered at an abattoir and were subjected to equi-biaxial testing. The results show that all the four material models yielded very good correlations at correlations above 96 %. The polynomial (anisotropic) model gave the best correlation of 98 %. However, the estimated material parameters varied widely from one test to another such that there would be needed to normalise the test data to avoid long optimisation processes after applying the average material parameters to finite element models. However, for application of the estimated material parameters to finite element models, there would be needed to consider normalising the test data to reduce the search region for the optimisation algorithms. Although the polynomial (anisotropic) model yielded the best correlation, it was found that the Choi-Vito had the least variation in the estimated material parameters thereby making it an easier option for application of its material parameters to a finite element model and also requiring minimum effort in the optimisation procedure. For the porcine sclera tissue, it was found that the anisotropy more influenced by the fiber-related properties than the background material matrix related properties.

Stochastic Dynamic Analysis of Structures with Spatially Uncertain Material Parameters

2014 ◽  
Vol 14 (08) ◽  
pp. 1440029 ◽  
Author(s):  
Kheirollah Sepahvand ◽  
Steffen Marburg
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Polynomial Chaos ◽  
Element Model ◽  
Stochastic Dynamic ◽  
Stochastic Field ◽  
Structural Dynamic ◽  
Material Parameters ◽  
Material Uncertainties ◽  
Stochastic Dynamic Analysis

This paper investigates the uncertainty quantification in structural dynamic problems with spatially random variation in material and damping parameters. Uncertain and locally varying material parameters are represented as stochastic field by means of the Karhunen–Loève (KL) expansion. The stiffness and damping properties of the structure are considered uncertain. Stochastic finite element of structural modal analysis is performed in which modal responses are represented using the generalized polynomial chaos (gPC) expansion. Knowing the KL expansions of the random parameters, the nonintrusive technique is employed on a set of random collocation points where the structure deterministic finite element model is executed to estimate the unknown coefficients of the polynomial chaos expansions. A numerical case study is presented for a cantilever beam with random Young's modulus involving spatial variation. The proportional damping constants are estimated from the experimental modal analysis. The expected value, standard deviation, and probability distribution of the random eigenfrequencies and the damping ratios are evaluated. The results show high accuracy compared to the Monte-Carlo (MC) simulations with 3000 realizations. It is also demonstrated that the eigenfrequencies and the damping ratios are equally affected from material uncertainties.

Accuracy and Robustness Analysis of Geometric Finite Element Model Updating Approach for Material Parameters Identification in Transient Dynamic

2018 ◽  
Vol 16 (01) ◽  
pp. 1850084 ◽  
Author(s):  
Clément Touzeau ◽  
Benoit Magnain ◽  
Quentin Serra ◽  
Éric Florentin
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Numerical Test ◽  
Robustness Analysis ◽  
Element Model ◽  
Finite Element Model Updating ◽  
Transient Dynamic ◽  
Material Parameters ◽  
Material Parameters Identification

We study the accuracy and the robustness of the Geometrical Finite Element Model Updating method proposed in Touzeau et al. [Touzeau, C., Magnain, B., Emile, B., Laurent, H. and Florentin, E. (2016) “Identification in transient dynamic using a geometry-based cost function in finite element model updating method,” Finite Elements Anal. Des. 122, 49–60]. In this work, the method is applied to transient dynamic in finite transformations to identify mechanical material parameters. A stochastic approach is performed to determine accuracy and robustness. The method is illustrated on numerical test cases and compared to a classical FEMU method. Uncertainties on the loading are taken into account in the identification using an original approach.

Optimization-Based Inverse Finite Element Analysis for Material Parameter Identification of a Biphasic Viscoelastic Hydrogel

2008 ◽  
Author(s):  
Kaifeng Liu ◽  
Brian Thomas ◽  
J. Craig Fryman ◽  
Jeff Bischoff ◽  
Timothy Ovaert ◽  
...  
Keyword(s):  
Finite Element ◽  
Solid Phase ◽  
Polymer Network ◽  
Viscoelastic Model ◽  
Optimization Method ◽  
Creep Testing ◽  
Material Parameter Identification ◽  
Element Analysis ◽  
Biphasic Model ◽  
Material Parameters

Hydrogels are a cross-linked network of polymer swollen with a liquid, and are promising replacements for diseased or damaged load bearing tissues such as articular cartilage [1]. Recently, a linear biphasic model, developed originally for cartilage [2], has been applied to characterize the mechanical behavior of hydrogels [3, 4]. However, the linear elastic assumption for the solid phase ignores the intrinsic viscoelasticity of the polymer network [3, 4]. Some attempts have been made in the literature to simulate hydrogels with a biphasic viscoelastic model using a self-developed finite element code [5]. This study is aimed at simulating hydrogels with a biphasic viscoelastic model and investigating an inverse finite element (FE) technique to identify material parameters of hydrogels via combined creep testing and FE modeling. Creep testing of hydrogels is simulated in the commercial software ABAQUS, which makes this approach easy to adapt to other test geometries. Material parameters are identified by fitting the FE results to the experimental results using an optimization method.

Modeling Infinitely Long Flexible Railroad Tracks Using Moving Modes and Krylov Subspaces Techniques

2013 ◽  
Author(s):  
Antonio M. Recuero ◽  
José L. Escalona
Keyword(s):  
Krylov Subspace ◽  
Complex Structure ◽  
Order Reduction ◽  
Element Model ◽  
Interesting Property ◽  
Krylov Subspaces ◽  
Flexible Body ◽  
Small Areas ◽  
Railroad Tracks ◽  
Flexible Track

This paper presents a method to model the flexibility of railroad tracks for the dynamic analysis of vehicle-track interaction. In addition to being a complex structure, the flexible track is infinitely long and shows small areas of deformation whose position moves with time. Due to these properties, the efficient modeling of the track as a flexible body in a multibody system formalism is a challenging problem. In this work the model is developed using the moving modes method in combination with Krylov subspaces techniques. The moving modes method that was previously presented by the authors defines the deformation modes in a trajectory frame whose position changes with respect to the flexible track. In this paper the moving modes are selected from a detailed finite element model of the track and a model order reduction technique based on Krylov subspaces. These modes of deformation are adequate to be selected as moving modes since they affect a small area of the flexible body and they are obtained by assuming the load distribution that actually takes place during the dynamic interaction. However, the most interesting property of the Krylov subspace modes is that they can be selected such that the frequency response function of the reduced order model matches that of the full model with the desired degree of accuracy. In this paper a multibody formulation of railroad vehicles and flexible tracks based on the trajectory frame is presented and applied to the numerical simulation of a full railroad car on a track with geometric irregularities.

Non-Linear Contact Analysis of an API Line Pipe Coupling

2009 ◽  
Author(s):  
Jeroen Van Wittenberghe ◽  
Patrick De Baets ◽  
Wim De Waele
Keyword(s):  
Material Properties ◽  
Element Model ◽  
Test Results ◽  
Line Pipe ◽  
Bending Fatigue ◽  
Material Parameters ◽  
Four Point Bending ◽  
Pipe Coupling ◽  
Contact Behaviour ◽  
The Finite Element Model

In this study, the finite element model of an API Line Pipe threaded pipe connection is presented. The non-linearities in material properties and contact behaviour are discussed. A series of modifications of the standard connection are simulated to gain a better understanding in the influence of geometrical and material parameters on the connection’s performance. Finally, test results obtained from a four-point bending fatigue experiment are presented and compared with numerical simulations.

Material parameter identification in functionally graded structures using isoparametric graded finite element model

2016 ◽  
Vol 23 (6) ◽  
pp. 685-698 ◽  
Author(s):  
Lixin Huang ◽  
Ming Yang ◽  
Xiaojun Zhou ◽  
Qi Yao ◽  
Lin Wang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Parameter Identification ◽  
Material Parameter ◽  
Element Model ◽  
Functionally Graded ◽  
Identification Algorithm ◽  
Material Parameter Identification ◽  
Measured Displacement ◽  
Graded Structures

AbstractAn identification algorithm based on an isoparametric graded finite element model is developed to identify the material parameters of the plane structure of functionally graded materials (FGMs). The material parameter identification problem is formulated as the problem of minimizing the objective function, which is defined as a square sum of differences between measured displacement and calculated displacement by the isoparametric graded finite element approach. The minimization problem is solved by using the Levenberg-Marquardt method, in which the sensitivity calculation is based on the differentiation of the governing equations of the isoparametric graded finite element model. The validity of this algorithm is illustrated by some numerical experiments. The numerical results reveal that the proposed algorithm not only has high accuracy and stable convergence, but is also robust to the effects of measured displacement noise.

Strength Testing of Fabric Composite Material and Impact Simulation for Airbag Landing System

2015 ◽  
Vol 1095 ◽  
pp. 463-467
Author(s):  
Jian Zheng Wei ◽  
Hui Feng Tan ◽  
Bo Song ◽  
Zhi Min Wan
Keyword(s):  
Composite Material ◽  
Element Model ◽  
Strength Testing ◽  
Soft Landing ◽  
Material Parameters ◽  
Impact Simulation ◽  
Inner Pressure ◽  
Silicone Coating ◽  
Fabric Composite ◽  
The Finite Element Model

The “Orion crew exploration vehicle” of NASA takes airbag as one way of landing system, which can reduce the landing weight, maintain the reposefully landing of the vehicle, protect the detector during recycling. In this paper, taking into account the material quality and the change during soft-landing of the airbag, the tensile mechanical properties tests of plain weave composite material airbag have been conducted at different temperature and different silicone coating thickness. Based on the material parameters of the test, the finite element model has been created to obtain the inner pressure and the overload curve of the airbag which has a certain angle with the ground. The result shows that the airbag made of fabric composite material can realize the landing and recycling of the vehicle.

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