Article
Mathematics, Interdisciplinary Applications
John Dean Van Tonder, Martin Philip Venter, Gerhard Venter
Summary: The inverse finite element method is used for material model parameter characterization. The paper presents a new method that resolves the problem of getting caught in local minima by utilizing a constrained optimization approach. The results demonstrate that this new method successfully isolates the optimal solution and reduces the variation between predicted parameters.
MATHEMATICAL AND COMPUTATIONAL APPLICATIONS
(2023)
Article
Engineering, Multidisciplinary
Michele Bacciocchi, Angelo Marcello Tarantino
Summary: This paper investigates the finite bending of hyperelastic beams made of transversely isotropic soft materials, developing a fully nonlinear three-dimensional beam model that includes the anticlastic effect. The study emphasizes the importance of considering the influence of transverse isotropy on stress components in various frameworks.
APPLIED MATHEMATICAL MODELLING
(2021)
Article
Robotics
Tilvawala Gopesh, James Friend
Summary: Accurate data representation of hyperelastic materials is crucial for soft robotics, and this study provides a method for determining the material properties effectively.
Article
Engineering, Chemical
Xiangfeng Peng, Lei Han, Luxian Li
Summary: A consistently compressible Mooney-Rivlin model is developed for vulcanized rubber based on Penn's experimental data, demonstrating near incompressibility. The model, which includes extra constants and considers normalization and consistency conditions, is compared with four other hyper-elastic models.
POLYMER ENGINEERING AND SCIENCE
(2021)
Article
Mechanics
Michael Lengger, Gunnar Possart, Paul Steinmann
Summary: The transition of polymer adhesives from a liquid to a fully cured state involves changes in stiffness, viscosity, and volume. This study presents a generic framework for simulating the curing process of adhesives, modified for a specific material type. The parameters of the material are determined through optimization with respect to photoelasticity measurements. However, this demonstration is currently only a proof-of-concept.
ARCHIVE OF APPLIED MECHANICS
(2022)
Article
Polymer Science
Mohammad Javad Azizli, Mohammad Barghamadi, Katayoon Rezaeeparto, Masoud Mokhtary, Somayeh Parham, Fatemeh Khademeh Molavi, Sedigheh Soltani
Summary: In this study, nanocomposites based on PA6/XNBR reinforced by OMMT were prepared, and the addition of XNBR-g-GMA compatibilizer and increased OMMT content was found to significantly improve the tensile strength, rheological and dynamic mechanical properties of the nanocomposites. The incorporation of Cloisite 30B as compared to Cloisite 20A resulted in substantial enhancement of the PA6/XNBR composite when XNBR-g-GMA was used as a compatibilizer.
JOURNAL OF APPLIED POLYMER SCIENCE
(2021)
Article
Engineering, Multidisciplinary
Hossein B. Khaniki, Mergen H. Ghayesh, Rey Chin
Summary: This paper presents a joint experimental and theoretical approach to studying the dynamics and mass sensitivity of hyperelastic plates, including cases with modal interactions. The accuracy of simulating the nonlinear dynamics of hyperelastic plate structures under different conditions is demonstrated using both theoretical and experimental methods. Furthermore, an analysis of the nonlinear forced vibration behavior of hyperelastic plates with different internal resonances and the ability of the structure for mass sensing are discussed.
INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE
(2023)
Article
Mechanics
Sae Sueki, Akimitsu Ishii, Sam Coppieters, Akinori Yamanaka
Summary: In this study, a novel inverse methodology for material model characterization was developed using an ensemble based four-dimensional variational method (En4DVar). The accuracy of the method was verified through numerical experiments in an elastoplastic finite element simulation of an aluminum alloy. The results showed that En4DVar is a powerful approach for estimating material parameters and characterizing deformation behavior.
INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES
(2023)
Article
Mechanics
Ben Wang, Qihui Lyu, Li Jiang, Yang Chen, Zaoyang Guo
Summary: In this study, an extended Hertz model is proposed to predict the mechanical responses of the incompressible Mooney-Rivlin half-space under finite spherical indentation. The contact behaviors are systematically investigated using an axisymmetric finite element (FE) model. Based on the numerical results, a reliable prediction of contact force is obtained by deriving the contact zone radius and incorporating it into the original Hertz model. A correction factor is introduced to account for the effect of constitutive parameter ratio on the contact force and pressure distribution. The extended Hertz model is effectively validated through FE simulations and experimental indentation results.
INTERNATIONAL JOURNAL OF APPLIED MECHANICS
(2022)
Article
Engineering, Mechanical
Dario Poloni, Daniele Oboe, Claudio Sbarufatti, Marco Giglio
Summary: The inverse Finite Element Method (iFEM) is used to reconstruct the full-field displacement on beam or shell structures using a network of strain sensors. A Gaussian Process is proposed as a strain pre-extrapolation and interpolation technique to provide strain values and compute the uncertainty on the reconstructed displacement field.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2023)
Article
Computer Science, Interdisciplinary Applications
Sebastian Bachmann, Dieter H. Pahr, Alexander Synek
Summary: The objective of this study was to assess the agreement between hFE-based IBR and mu FE-based IBR in predicting hip joint loading. The results showed that using hFE models significantly reduced the computational time and improved the prediction of joint loading history. The study suggests that cortical and trabecular bone should be modeled separately, and at least density-dependent heterogeneous material properties should be used with hFE models to predict joint loading.
COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE
(2023)
Article
Engineering, Mechanical
Matteo Pelliciari, Stefano Sirotti, Angelo Aloisio, Angelo Marcello Tarantino
Summary: In this study, an accurate analytical expression for the pressure-deflection curve of inflated membranes is derived. The proposed model is validated with finite element simulations and shown to be more accurate than other existing solutions, with the added advantage of being applicable to compressible materials. Experimental tests on rubber materials are conducted, and the proposed model is used to characterize the constitutive parameters. The accurate and easy-to-use pressure-deflection formula is an innovative tool in engineering applications of inflated membranes.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Engineering, Mechanical
I. J. Sanchez-Arce, D. C. Goncalves, L. D. C. Ramalho, R. D. S. G. Campilho, J. Belinha
Summary: The implementation of the Ogden model into the NNRPIM allows for accurate modeling of hyperelastic behavior in rubber-like materials and biological tissues. The results show that the NNRPIM models have similar stress distributions to FEM models for strains below 10%, making it suitable for modeling neo-Hookean, Mooney-Rivlin, and Ogden materials.
JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING
(2023)
Article
Engineering, Mechanical
Tian Xu, Zhen Wang, Yingda Hu, Shilun Du, Yong Lei
Summary: In this paper, a multiple-data-based direct (MD) method is proposed to solve the inverse problem of estimating the unknown Young's modulus and boundary conditions of an elastic object. It avoids the need for iterative methods. The proposed method applies a global normalized objective function and a global regularization coefficient for energy-like regularization, ensuring the convergence of the unknown displacement boundary conditions. Moreover, a multi-force-position method is proposed to obtain observation data, improving the accuracy of the MD method when the number of experiments is limited. Both numerical and physical experiments confirm that the MD method provides more accurate estimation of Young's modulus and boundary conditions compared to previous single-data-based direct (SD) methods.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2023)
Article
Engineering, Multidisciplinary
Shengwen Tu, Naoki Morita, Tsutomu Fukui, Kazuki Shibanuma
Summary: This study aimed to extend the finite element method to cope with elastic-plastic problems by introducing the s-version FEM. The s-version FEM, which overlays a set of local mesh with fine element size on the conventional FE mesh, simplifies domain discretisation and provides accurate numerical predictions. Previous applications of the s-version FEM were limited to elastic problems, lacking instructions for stress update in plasticity. This study presents detailed instructions and formulations for addressing plasticity problems with the s-version FEM and analyzes a stress concentration problem with linear/nonlinear material properties.
APPLIED MATHEMATICAL MODELLING
(2024)
Article
Robotics
David Rostin Ellis, Martin Philip Venter, Gerhard Venter
Summary: The deformation behavior of soft pneumatic actuators can be preprogrammed into their architecture during design. This paper introduces a bimodal design to achieve distinct deformation directions in one actuator by changing pneumatic pressure. The study shows that it is possible to alter the pressure at which this transition occurs by changing the crimp ratio of the embedded bilinear material.
Article
Robotics
David Rostin Ellis, Martin Philip Venter, Gerhard Venter
Summary: A modular actuator construction was designed using smaller articulating units in series to build soft pneumatic actuators, with a design tool developed to optimize the design through genetic algorithm. The inflated actuators closely resembled the desired profile in tests, with a very small average deviation between physical and numerical models.
Article
Engineering, Civil
B. Bezuidenhout, G. Venter, M. P. Venter
Summary: This research presents a design methodology to determine the uninflated geometry of inflatable wings, accurately fitting a target profile. Numerical experiments demonstrate the robustness of the proposed methodology and the accurate prediction of the inflated shape of the numerical model for corresponding physical models.
JOURNAL OF THE INTERNATIONAL ASSOCIATION FOR SHELL AND SPATIAL STRUCTURES
(2022)
Article
Mathematics, Interdisciplinary Applications
John Dean Van Tonder, Martin Philip Venter, Gerhard Venter
Summary: The inverse finite element method is used for material model parameter characterization. The paper presents a new method that resolves the problem of getting caught in local minima by utilizing a constrained optimization approach. The results demonstrate that this new method successfully isolates the optimal solution and reduces the variation between predicted parameters.
MATHEMATICAL AND COMPUTATIONAL APPLICATIONS
(2023)
Article
Mathematics, Interdisciplinary Applications
Julianne Blignaut, Martin Venter, David van den Heever, Mark Solms, Ivan Crockart
Summary: This study explores the use of a virtual-reality headset as an alternative to a mirror stereoscope for studying binocular rivalry. The results suggest that a virtual-reality headset can effectively induce binocular rivalry, but there are differences in visual stability compared to the traditional mirror stereoscope.
MATHEMATICAL AND COMPUTATIONAL APPLICATIONS
(2023)
Article
Mathematics, Interdisciplinary Applications
Martin Philip Venter, Naude Thomas Conradie
Summary: This paper compares three explicitly defined intermediate encoding methods in generative design for two-dimensional soft robotic units. The results suggest that the Lindenmayer system encoding generates candidate units with fewer function evaluations, but produces a less diverse population. In contrast, the Compositional Pattern Producing Network encoding produces a similar diversity of candidate units and a higher number of high-performing units. Overall, the Compositional Pattern Producing Network encoding is a viable alternative for designing soft robotic actuators with desirable performance characteristics.
MATHEMATICAL AND COMPUTATIONAL APPLICATIONS
(2023)
Article
Mathematics, Interdisciplinary Applications
Rhoda Ngira Aduke, Martin P. Venter, Corne J. Coetzee
Summary: Corrugated paperboard is a sandwich structure consisting of wavy paper (fluting) sandwiched between two flat paper sheets (liners). Due to its waved geometry, analyzing the entire package using three-dimensional numerical finite element models is computationally expensive. Homogenization techniques are used to evaluate equivalent homogeneous models with similar material properties. This study analyzes the application of three homogenization techniques and their effectiveness in evaluating the elastic material properties of corrugated paperboard, comparing them to the inverse method in modeling bending tests.
MATHEMATICAL AND COMPUTATIONAL APPLICATIONS
(2023)
Article
Mathematics, Interdisciplinary Applications
Philip Frederik Ligthart, Martin Philip Venter
Summary: This paper illustrates the effectiveness of a hierarchical design framework for developing environment-specific behavior in fluid-actuated soft robots. The proposed framework uses multi-step optimization and reduced-order modeling to minimize the computational cost involved in simulating non-linear materials during the design process. By making high-level decisions to simplify the optimizations and targeting simpler objectives in earlier steps, and more complex objectives in later steps, the framework achieves significantly better solutions in much less time compared to a direct design approach. A case study comparing the hierarchical framework to a conventional direct design approach for a simple 2D design demonstrates the superior performance of the hierarchical framework.
MATHEMATICAL AND COMPUTATIONAL APPLICATIONS
(2023)
Article
Mathematics, Interdisciplinary Applications
Martin Philip Venter, Izak Johannes Joubert
Summary: This paper presents a practical generative design process for designing soft robots. The method reduces design time while involving human designers and facilitating the use of other numerical techniques. By combining different techniques, the authors successfully designed functional 2D articulating soft robots and extended the approach to more complex 3D robot designs.
MATHEMATICAL AND COMPUTATIONAL APPLICATIONS
(2023)
Article
Agricultural Engineering
Pascal Marggraff, Martin Philip Venter
Proceedings Paper
Engineering, Civil
E. J. van Zyl, M. P. Venter
ADVANCES IN ENGINEERING MATERIALS, STRUCTURES AND SYSTEMS: INNOVATIONS, MECHANICS AND APPLICATIONS
(2019)
Proceedings Paper
Engineering, Civil
C. F. Jekel, R. T. Haftka, M. P. Venter, G. Venter
ADVANCES IN ENGINEERING MATERIALS, STRUCTURES AND SYSTEMS: INNOVATIONS, MECHANICS AND APPLICATIONS
(2019)
Proceedings Paper
Engineering, Civil
B. Bezuidenhout, G. Venter, M. P. Venter
ADVANCES IN ENGINEERING MATERIALS, STRUCTURES AND SYSTEMS: INNOVATIONS, MECHANICS AND APPLICATIONS
(2019)
Proceedings Paper
Engineering, Electrical & Electronic
David R. Ellis, Martin P. Venter, Gerhard Venter
2019 2ND IEEE INTERNATIONAL CONFERENCE ON SOFT ROBOTICS (ROBOSOFT 2019)
(2019)
Article
Mathematics, Applied
Guo Zheng, Zengqiang Cao, Yuehaoxuan Wang, Reza Talemi
Summary: This study introduces two novel methods for predicting the fatigue response of Dynamic Cold Expansion (DCE) and Static Cold Expansion (SCE) open-hole plates. The accuracy of the prediction is enhanced by considering stress distributions and improving existing methods. The study also discusses the mechanisms behind fatigue life enhancement and fatigue crack propagation modes in cold expansion specimens.
FINITE ELEMENTS IN ANALYSIS AND DESIGN
(2024)
Article
Mathematics, Applied
Eric Heppner, Tomohiro Sasaki, Frank Trommer, Elmar Woschke
Summary: This paper presents a modeling approach for estimating the bonding strength of friction-welded lightweight structures. Through experiments and simulations, a method for evaluating the bonding strength of friction-welded lightweight structures is developed, and the plausibility and applicability of the model are discussed.
FINITE ELEMENTS IN ANALYSIS AND DESIGN
(2024)
Article
Mathematics, Applied
Piermario Vitullo, Alessio Colombo, Nicola Rares Franco, Andrea Manzoni, Paolo Zunino
Summary: Many applications in computational physics involve approximating problems with microstructure, characterized by multiple spatial scales in their data. However, these numerical solutions are often computationally expensive due to the need to capture fine details at small scales. Traditional projection based reduced order models (ROMs) fail to resolve these issues, even for second-order elliptic PDEs commonly found in engineering applications. To address this, we propose an alternative nonintrusive strategy to build a ROM, that combines classical proper orthogonal decomposition (POD) with a suitable neural network (NN) model to account for the small scales.
FINITE ELEMENTS IN ANALYSIS AND DESIGN
(2024)
Article
Mathematics, Applied
Chanh Dinh Vuong, Xiaofei Hu, Tinh Quoc Bui
Summary: In this paper, we present a dynamic description of the smoothing gradient-enhanced damage model for the simulation of quasi-brittle failure localization under time-dependent loading conditions. We introduce two efficient rate-dependent damage laws and various equivalent strain formulations to analyze the complicated stress states and inertia effects of the dynamic regime, enhancing the capability of the adopted approach in modeling dynamic fracture and branching.
FINITE ELEMENTS IN ANALYSIS AND DESIGN
(2024)
Article
Mathematics, Applied
Alexandre D. C. Amaro, A. Francisca Carvalho Alves, F. M. Andrade Pires
Summary: This study focuses on analyzing various deformation mechanisms that affect the behavior of PC/ABS blends using computational homogenization. By establishing a representative microstructural volume element, defining the constitutive description of the material phases, and modeling the interfaces and matrix damage, accurate predictions can be achieved. The findings have important implications for broader applications beyond PC/ABS blends.
FINITE ELEMENTS IN ANALYSIS AND DESIGN
(2024)
Article
Mathematics, Applied
David Hoffmeyer, A. R. Damanpack
Summary: This paper introduces a method for determining all six stress components for a cantilever-type beam that is subjected to concentrated end loads. The method considers an inhomogeneous cross-section and employs cylindrically orthotropic material properties. The efficacy of the method is validated by numerical examples and a benchmark example, and the analysis on a real sawn timber cross-section reveals significant disparities in the maximum stresses compared to conventional engineering approaches.
FINITE ELEMENTS IN ANALYSIS AND DESIGN
(2024)
Article
Mathematics, Applied
Vladimir Stojanovic, Jian Deng, Dunja Milic, Marko D. Petkovic
Summary: The present paper investigates the dynamic analysis of a coupled Timoshenko beam-beam or beam-arch mechanical system with geometric nonlinearities. A modified p-version finite element method is developed for the vibrations of a shear deformable coupled beam system with a discontinuity in an elastic layer. The main contribution of this work is the discovery of coupled effects and phenomena in the simultaneous vibration analysis of varying discontinuity and varying curvature of the newly modelled coupled mechanical system. The analysis results are valuable and have broader applications in the field of solids and structures.
FINITE ELEMENTS IN ANALYSIS AND DESIGN
(2024)
Article
Mathematics, Applied
Gihwan Kim, Phill-Seung Lee
Summary: The phantom-node method is applied in the phase field model for mesh coarsening to improve computational efficiency. By recovering the fine mesh in the crack path domain into a coarse mesh, this method significantly reduces the number of degrees of freedom involved in the computation.
FINITE ELEMENTS IN ANALYSIS AND DESIGN
(2024)
Article
Mathematics, Applied
Souhail Chaouch, Julien Yvonnet
Summary: In this study, an unsupervised machine learning-based clustering approach is developed to reduce the computational cost of nonlinear multiscale methods. The approach clusters macro Gauss points based on their mechanical states, reducing the problem from macro scale to micro scale. A single micro nonlinear Representative Volume Element (RVE) calculation is performed for each cluster, using a linear approximation of the macro stress. Anelastic macro strains are used to handle internal variables. The technique is applied to nonlinear hyperelastic, viscoelastic and elastoplastic composites.
FINITE ELEMENTS IN ANALYSIS AND DESIGN
(2024)
Article
Mathematics, Applied
Hoang-Giang Bui, Jelena Ninic, Christian Koch, Klaus Hackl, Guenther Meschke
Summary: With the increasing demand for underground transport infrastructures, it is crucial to develop methods and tools that efficiently explore design options and minimize risks to the environment. This study proposes a BIM-based approach that connects user-friendly software with effective simulation tools to analyze complex tunnel structures. The results show that modeling efforts and computational time can be significantly reduced while maintaining high accuracy.
FINITE ELEMENTS IN ANALYSIS AND DESIGN
(2024)
Article
Mathematics, Applied
Aslan Nasirov, Xiaoyu Zhang, David Wagner, Saikumar R. Yeratapally, Caglar Oskay
Summary: This manuscript presents an efficient model construction strategy for the eigenstrain homogenization method (EHM) for the reduced order models of the nonlinear response of heterogeneous microstructures. The strategy relies on a parallel, element-by-element, conjugate gradient solver, achieving near linear scaling with respect to the number of degrees of freedom used to resolve the microstructure. The linear scaling in the number of pre-analyses required to construct the reduced order model (ROM) follows from the EHM formulation. The developed framework has been verified using an additively manufactured polycrystalline microstructure of Inconel 625.
FINITE ELEMENTS IN ANALYSIS AND DESIGN
(2024)
Article
Mathematics, Applied
Atticus Beachy, Harok Bae, Jose A. Camberos, Ramana V. Grandhi
Summary: Emulator embedded neural networks leverage multi-fidelity data sources for efficient design exploration of aerospace engineering systems. However, training the ensemble models can be costly and pose computational challenges. This work presents a new type of emulator embedded neural network using the rapid neural network paradigm, which trains near-instantaneously without loss of prediction accuracy.
FINITE ELEMENTS IN ANALYSIS AND DESIGN
(2024)
Article
Mathematics, Applied
Arash Hajisharifi, Michele Girfoglio, Annalisa Quaini, Gianluigi Rozza
Summary: This paper introduces three reduced order models for reducing computational time in atmospheric flow simulation while preserving accuracy. Among them, the PODI method, which uses interpolation with radial basis functions, maintains accuracy at any time interval.
FINITE ELEMENTS IN ANALYSIS AND DESIGN
(2024)
Article
Mathematics, Applied
D. Munoz, S. Torregrosa, O. Allix, F. Chinesta
Summary: The Proper Generalized Decomposition (PGD) is a Model Order Reduction framework used for parametric analysis of physical problems. It allows for offline computation and real-time simulation in various situations. However, its efficiency may decrease when the domain itself is considered as a parameter. Optimal transport techniques have shown exceptional performance in interpolating fields over geometric domains with varying shapes. Therefore, combining these two techniques is a natural choice. PGD handles the parametric solution while the optimal transport-based methodology transports the solution for a family of domains defined by geometric parameters.
FINITE ELEMENTS IN ANALYSIS AND DESIGN
(2024)
Article
Mathematics, Applied
Jothi Mani Thondiraj, Akhshaya Paranikumar, Devesh Tiwari, Daniel Paquet, Pritam Chakraborty
Summary: This study develops a diffused interface CPFEM framework, which reduces computational cost by using biased mesh and provides accurate results using non-conformal elements in the mesh size transiting regions. The accuracy of the framework is confirmed through comparisons with sharp and stepped interface results.
FINITE ELEMENTS IN ANALYSIS AND DESIGN
(2024)
