scholarly journals Calculation Approaches for Determining the Sliding Friction Coefficient – Analytical Consideration and FE-Modelling

2020 ◽  
Vol 1 ◽  
pp. 95-106
Author(s):  
André Bergmann ◽  
Niels Dallinger ◽  
Timo Bensing ◽  
Yvonne Keil ◽  
Markus Golder ◽  
...  
Keyword(s):  
Sliding Friction ◽  
Analytical Calculation ◽  
Material Model ◽  
Complex Interaction ◽  
Polymer Surfaces ◽  
Fe Model ◽  
Fe Modelling ◽  
Material Parameters ◽  
Surface Areas ◽  
Sliding Friction Coefficient

Microstructures on polymer surfaces are known to reduce friction and thevisibility of scratches. Due to the complex interaction of multiple surface areas in contactwith each other the prediction of coefficient of friction (COF) or wear is difficult and dependson an empirical solution. This article deals with possibilities of calculating the deformingpart of friction via an analytical solution and a FE-model. In a first step the modelling ofsingle contacts is demonstrated. The analytical calculation based on the Hertzian contactequations is extended regarding viscoelastic material parameters. The basic approach ofFE-modelling is explained including calibration of the material model using the softwareMCalibration®. The article introduces the different procedures of simulating and modellingCOF and wear taking into account the area of contact and resulting stress distribution.

scholarly journals NUMERICAL SIMULATION OF THE BLAST-RESISTANT RESPONSE OF ULTRAHIGH-PERFORMANCE CONCRETE STRUCTURAL MEMBERS

2019 ◽  
Vol 25 (6) ◽  
pp. 587-598 ◽  
Author(s):  
Hor Yin ◽  
Kazutaka Shirai ◽  
Wee Teo
Keyword(s):  
Damage Model ◽  
High Strength ◽  
Material Model ◽  
Experimental Results ◽  
Fe Model ◽  
Structural Members ◽  
Fe Modelling ◽  
Constitutive Material Model ◽  
Concrete Damage ◽  
Explicit Solver

This paper presents the blast responses of ultrahigh-performance concrete (UHPC) structural members obtained using finite element (FE) modelling. The FE model was developed using LS-DYNA with an explicit solver. In the FE simulation, the concrete damage model, which is a plasticity-based constitutive material model, was employed for the concrete material. The simulation results were verified against previous experimental results available in the literature and were shown to be in good agreement with the experimental results. In addition, the developed FE model was implemented in a parametric study by varying the blast weight charges. The numerical results for UHPC members were compared with those for conventional reinforced concrete (RC) members. The numerical responses, such as the maximum deflections, deflected shapes, and damage patterns, of the UHPC members subjected to blast loading were significantly better performance than those of the RC members as a result of the high strength and ductile capacity of UHPC.

Representation of bolted joints in a structure using finite element modelling and model updating

2020 ◽  
Vol 14 (3) ◽  
pp. 7141-7151 ◽  
Author(s):  
R. Omar ◽  
M. N. Abdul Rani ◽  
M. A. Yunus
Keyword(s):  
Finite Element ◽  
Dynamic Behaviour ◽  
Model Updating ◽  
Complex Structure ◽  
Bolted Joints ◽  
Model Parameters ◽  
Fe Model ◽  
Bolted Joint ◽  
Fe Modelling ◽  
Joint Structure

Efficient and accurate finite element (FE) modelling of bolted joints is essential for increasing confidence in the investigation of structural vibrations. However, modelling of bolted joints for the investigation is often found to be very challenging. This paper proposes an appropriate FE representation of bolted joints for the prediction of the dynamic behaviour of a bolted joint structure. Two different FE models of the bolted joint structure with two different FE element connectors, which are CBEAM and CBUSH, representing the bolted joints are developed. Modal updating is used to correlate the two FE models with the experimental model. The dynamic behaviour of the two FE models is compared with experimental modal analysis to evaluate and determine the most appropriate FE model of the bolted joint structure. The comparison reveals that the CBUSH element connectors based FE model has a greater capability in representing the bolted joints with 86 percent accuracy and greater efficiency in updating the model parameters. The proposed modelling technique will be useful in the modelling of a complex structure with a large number of bolted joints.

Lifetime Prediction of Tires with Regard to Oxidative Aging5

2008 ◽  
Vol 36 (1) ◽  
pp. 63-79 ◽  
Author(s):  
L. Nasdala ◽  
Y. Wei ◽  
H. Rothert ◽  
M. Kaliske
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Temperature Distribution ◽  
Superposition Principle ◽  
Accelerated Aging ◽  
Material Model ◽  
Aging Behavior ◽  
Element Analysis ◽  
Material Parameters ◽  
Reaction Processes

Abstract It is a challenging task in the design of automobile tires to predict lifetime and performance on the basis of numerical simulations. Several factors have to be taken into account to correctly estimate the aging behavior. This paper focuses on oxygen reaction processes which, apart from mechanical and thermal aspects, effect the tire durability. The material parameters needed to describe the temperature-dependent oxygen diffusion and reaction processes are derived by means of the time–temperature–superposition principle from modulus profiling tests. These experiments are designed to examine the diffusion-limited oxidation (DLO) effect which occurs when accelerated aging tests are performed. For the cord-reinforced rubber composites, homogenization techniques are adopted to obtain effective material parameters (diffusivities and reaction constants). The selection and arrangement of rubber components influence the temperature distribution and the oxygen penetration depth which impact tire durability. The goal of this paper is to establish a finite element analysis based criterion to predict lifetime with respect to oxidative aging. The finite element analysis is carried out in three stages. First the heat generation rate distribution is calculated using a viscoelastic material model. Then the temperature distribution can be determined. In the third step we evaluate the oxygen distribution or rather the oxygen consumption rate, which is a measure for the tire lifetime. Thus, the aging behavior of different kinds of tires can be compared. Numerical examples show how diffusivities, reaction coefficients, and temperature influence the durability of different tire parts. It is found that due to the DLO effect, some interior parts may age slower even if the temperature is increased.

scholarly journals CAD-Based 3D-FE Modelling of AISI-D3 Turning with Ceramic Tooling

Machines ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 4
Author(s):  
Panagiotis Kyratsis ◽  
Anastasios Tzotzis ◽  
Angelos Markopoulos ◽  
Nikolaos Tapoglou
Keyword(s):  
Statistical Model ◽  
Cutting Speed ◽  
Depth Of Cut ◽  
Fe Model ◽  
Fe Modelling ◽  
3D Finite Element ◽  
Force Components ◽  
Four Levels ◽  
The Relationship ◽  
Strong Agreement

In this study, the development of a 3D Finite Element (FE) model for the turning of AISI-D3 with ceramic tooling is presented, with respect to four levels of cutting speed, feed, and depth of cut. The Taguchi method was employed in order to create the orthogonal array according to the variables involved in the study, reducing this way the number of the required simulation runs. Moreover, the possibility of developing a prediction model based on well-established statistical tools such as the Response Surface Methodology (RSM) and the Analysis of Variance (ANOVA) was examined, in order to further investigate the relationship between the cutting speed, feed, and depth of cut, as well as their influence on the produced force components. The findings of this study point out an increased correlation between the experimental results and the simulated ones, with a relative error below 10% for most tests. Similarly, the values derived from the developed statistical model indicate a strong agreement with the equivalent numerical values due to the verified adequacy of the statistical model.

scholarly journals Flexural behavior of composite structural insulated panels with magnesium oxide board facings

2020 ◽  
Vol 20 (4) ◽  
Author(s):  
Łukasz Smakosz ◽  
Ireneusz Kreja ◽  
Zbigniew Pozorski
Keyword(s):  
Magnesium Oxide ◽  
Material Model ◽  
Expanded Polystyrene ◽  
Flexural Behavior ◽  
Joint Analysis ◽  
Model Parameters ◽  
Fe Model ◽  
Computational Results ◽  
Four Point Bending ◽  
Proposed Model

Abstract The current report is devoted to the flexural analysis of a composite structural insulated panel (CSIP) with magnesium oxide board facings and expanded polystyrene (EPS) core, that was recently introduced to the building industry. An advanced nonlinear FE model was created in the ABAQUS environment, able to simulate the CSIP’s flexural behavior in great detail. An original custom code procedure was developed, which allowed to include material bimodularity to significantly improve the accuracy of computational results and failure mode predictions. Material model parameters describing the nonlinear range were identified in a joint analysis of laboratory tests and their numerical simulations performed on CSIP beams of three different lengths subjected to three- and four-point bending. The model was validated by confronting computational results with experimental results for natural scale panels; a good correlation between the two results proved that the proposed model could effectively support the CSIP design process.

The use of plastic details to increase the contact surface of the substrate during the cultivation of attached species of algae

2021 ◽  
pp. 110-123
Author(s):  
Olga Yu. Kalinina ◽  
Philipp V. Sapozhnikov ◽  
Anastasiya A. Snigirova ◽  
Alexey I. Salimon ◽  
Yaroslava V. Kaliaeva
Keyword(s):  
Contact Surface ◽  
Polymer Surfaces ◽  
Individual Species ◽  
Nutrient Media ◽  
Inhomogeneous Surface ◽  
Surface Areas ◽  
Fine Mesh ◽  
Series Of Experiments ◽  
Solid Nutrient Medium ◽  
Effective Growth

A series of experiments was carried out using strips (and nets) of synthetic polymers to increase the contact surface during the cultivation of attached forms of microphytes. We used bands of different composition, as well as with different microrelief surface areas, and a fine-mesh PLA network with an inhomogeneous surface. The experiments were performed on liquid nutrient media in accumulative cultures, and on solid nutrient medium in pure culture. The results showed a number of positive features of such cultivation, based on the selective isolation of individual species and their small combinations from the composition of accumulative cultures, as well as on the effective growth of individual species on specific elements of the microrelief of polymer surfaces. The polymers used were: PET, PP, LDPE, UHMWPE and PLA.

scholarly journals On the recovery of the stress-free configuration of the human cornea

2020 ◽  
Vol 2 (4) ◽  
pp. 11-33
Author(s):  
Anna Pandolfi ◽  
Andrea Montanino
Keyword(s):  
Numerical Simulations ◽  
Inverse Analysis ◽  
Material Model ◽  
Free State ◽  
Human Cornea ◽  
Material Models ◽  
Material Parameters ◽  
Optimal Values ◽  
Stress Free State ◽  
Actual Stress

Purpose: The geometries used to conduct numerical simulations of the biomechanics of the human cornea are reconstructed from images of the physiological configuration of the system, which is not in a stress-free state because of the interaction with the surrounding tissues. If the goal of the simulation is a realistic estimation of the mechanical engagement of the system, it is mandatory to obtain a stress-free configuration to which the external actions can be applied. Methods: Starting from a unique physiological image, the search of the stress-free configuration must be based on methods of inverse analysis. Inverse analysis assumes the knowledge of one or more geometrical configurations and, chosen a material model, obtains the optimal values of the material parameters that provide the numerical configurations closest to the physiological images. Given the multiplicity of available material models, the solution is not unique. Results: Three exemplary material models are used in this study to demonstrate that the obtained, non-unique, stress-free configuration is indeed strongly dependent on both material model and on material parameters. Conclusion: The likeliness of recovering the actual stress-free configuration of the human cornea can be improved by using and comparing two or more imaged configurations of the same cornea.

scholarly journals Numerical Study on Surface Roughness Measurement Based on Nonlinear Ultrasonics in Through-Transmission and Pulse-Echo Modes

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4855
Author(s):  
Maodan Yuan ◽  
Anbang Dai ◽  
Lin Liao ◽  
Yan Chen ◽  
Xuanrong Ji
Keyword(s):  
Surface Roughness ◽  
Numerical Study ◽  
Material Model ◽  
Nonlinearity Parameter ◽  
Fe Model ◽  
Roughness Measurement ◽  
Monitoring Method ◽  
Surface Roughness Measurement ◽  
Nonlinear Ultrasonics ◽  
Pulse Echo

Ultrasonic is one of the well-known methods for surface roughness measurement, but small roughness will only lead to a subtle variation of transmission or reflection. To explore sensitive techniques for surfaces with small roughness, nonlinear ultrasonic measurement in through-transmission and pulse-echo modes was proposed and studied based on an effective unit-cell finite element (FE) model. Higher harmonic generation in solids was realized by applying the Murnaghan hyperelastic material model. This FE model was verified by comparing the absolute value of the nonlinearity parameter with the analytical solution. Then, random surfaces with different roughness values ranging from 0 μm to 200 μm were repeatedly generated and studied in the two modes. The through-transmission mode is very suitable to measure the surfaces with roughness as small as 3% of the wavelength. The pulse-echo mode is sensitive and effective to measure the surface roughness ranging from 0.78% to 5.47% of the wavelength. This study offers a potential nondestructive testing and monitoring method for the interfaces or inner surfaces of the in-service structures.

scholarly journals Identification of orthotropic material parameters for acute, necrotic, fibrotic and remodelling myocardial infarcts in the rat

2019 ◽  
Author(s):  
Mazin S. Sirry ◽  
Laura Dubuis ◽  
Neil H. Davies ◽  
Jun Liao ◽  
Thomas Franz
Keyword(s):  
Constitutive Model ◽  
Orthotropic Material ◽  
Constitutive Models ◽  
Biaxial Stress ◽  
Percentage Error ◽  
Fe Model ◽  
Stress Strain ◽  
Material Parameters ◽  
Strain Data ◽  
Tensile Experiment

AbstractFinite element (FE) models have been effectively utilized in studying biomechanical aspects of myocardial infarction (MI). Although the rat is a widely used animal model for MI, there is a lack of material parameters based on anisotropic constitutive models for rat myocardial infarcts in literature. This study aimed at employing inverse methods to identify the parameters of an orthotropic constitutive model for myocardial infarcts in the acute, necrotic, fibrotic and remodelling phases utilizing the biaxial mechanical data developed in a previous study. FE model was developed mimicking the setup of the biaxial tensile experiment. The orthotropic case of the generalized Fung constitutive model was utilized to model the material properties of the infarct. The parameters of Fung model were optimized so that the FE solution best fitted the biaxial experimental stress-strain data. A genetic algorithm was used to minimize the objective function. Fung orthotropic material parameters for different infarct stages were identified. The FE model predictions best approximated the experimental data of the 28 days infarct stage with 3.0% mean absolute percentage error. The worst approximation was for the 7 days stage with 3.6% error. This study demonstrated that the experimental biaxial stress-strain data of healing rat infarcts could be successfully approximated using inverse FE methods and genetic algorithms. The material parameters identified in this study will provide an essential platform for FE investigations of biomechanical aspects of MI and the development of therapies.

Dynamic Actuation of Electro-Elastic Spherical Membranes Using Dielectric Elastomers

Aerospace ◽  
2005 ◽  
Author(s):  
Nakhiah Goulbourne ◽  
Eric Mockensturm ◽  
Mary Frecker
Keyword(s):  
Dynamic Response ◽  
Applied Voltage ◽  
Gas Flow ◽  
Applied Pressure ◽  
Material Model ◽  
Dielectric Elastomer ◽  
Inertial Effects ◽  
Mechanical Pressure ◽  
Material Parameters ◽  
Dielectric Elastomer Actuators

This paper presents dynamic results for spherical dielectric elastomer actuators subject to an inflating mechanical pressure and an applied voltage. Different equilibria modes arise during dynamic operation due to inertial effects. In previous work, the inertial effects have been studied for the limited case of a constant applied pressure during membrane deformation [1]. Here, novel results are presented in which the dynamic response of spherical dielectric elastomer actuators to a pressure-time loading history as well as a more realistic constant gas flow rate are considered. The results are calculated for both the damped and the zero-damped cases. The spherical membrane is assumed to follow the Mooney material model where various inflation modes arise depending on the material parameters. The range of Mooney material parameters considered, the driving pressure and the applied voltage all affect the dynamic response.

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