ORCID Profile
0000-0003-3253-6208
Current Organisation
Deakin University
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Publisher: Elsevier BV
Date: 2023
Publisher: Elsevier BV
Date: 06-2021
Publisher: Springer Science and Business Media LLC
Date: 07-05-2022
DOI: 10.1007/S00107-022-01820-8
Abstract: A reliable and efficient numerical modelling technique is essential to investigate the behaviour of timber and engineered timber products to promote their widespread use in construction. Wood is an anisotropic material and hence its mechanical properties largely depend on grain direction and type of loading i.e., material behaves differently under compression and tension. Material responses under tension parallel and perpendicular to the grain directions have been reported in the literature but the relevant progressive fracture behaviour has been ignored in typical numerical simulations, due to the complexities and uncertainties around modelling as well as lack of reliable test data. Fracture characteristics play a significant role in analysing crack initiation, propagation, and failure modes of timber so that its full potential can be utilised by knowing the post-elastic behaviour. This paper applies and compares four continuum damage mechanics based constitutive material models (MAT-22, MAT54/55, MAT-143 and MAT-261) available in the commercial finite element software LS-DYNA for simulating the post-elastic behaviour of general timber lamella products. Timber was modelled as both orthotropic and transversely isotropic material to simulate the fracture behaviour in tensile load cases. It is shown that the predicted fracture properties correlate well with experimental data. It was observed that all considered built-in continuum damage models in LS-DYNA are able to simulate the elastic response, but MAT-261, which was originally developed for modelling fibre reinforced composite materials, provides a simple yet reliable option for simulating fracture behaviour of timber.
Publisher: MDPI AG
Date: 19-09-2022
DOI: 10.3390/BUILDINGS12091490
Abstract: The mechanical properties of the structural components (i.e., columns and beams produced from engineered bamboo products), such as, bamboo scrimber (also known as parallel bamboo strand lumber, PBSL) and Laminated Bamboo Lumber (LBL), have attracted considerable attention from researchers in recent years. In previous studies, researchers reported on the stress-strain behaviour of bamboo scrimber, LBL and glue laminated bamboo under compression and proposed some empirical and semi-empirical models, based on their in idual studies. However, a generic constitutive model for engineered bamboo products is still not available. The compressive stress-strain curves of bamboo scrimber and LBL are reported to show a similar behaviour with three distinct stages i.e., a linear elastic stage followed by a nonlinear plastic stage and a plateau. As part of the current study, the previously proposed models for bamboo scrimber were carefully studied and all available material test results on engineered bamboo were used to develop a generic constitutive model, based on the Ramberg-Osgood (RO) formulation considering its suitability to capture its material nonlinearity. Based on the test results, it was observed that 1% proof stress can be used in a compound RO model to predict an accurate material response for bamboo scrimber. The proposed modelling technique has also been applied to predict the compressive behaviour of LBL. This paper proposes the RO coefficients for both bamboo scrimber and LBL that can be used to develop accurate nonlinear models for engineered bamboo products.
Publisher: World Scientific Pub Co Pte Ltd
Date: 22-03-2023
DOI: 10.1142/S0219876222410043
Abstract: Advances in testing of composite materials in recent years have mostly resulted in the ability to actively characterize the uniaxial response of composites while investigations of multiaxial load cases are rare due to various challenges. One of these challenges is the lack of a suitable specimen geometry for multiaxial testing without unwanted failure modes. Ideally, such geometry should be developed and assessed virtually by means of simulation before costly and time-consuming manufacturing and testing. Therefore, reliable, and efficient simulation methods are required that incorporate the evolution of damage in FRP composites. This study investigates various geometric features virtually of cruciform specimens to test fiber-reinforced composites subjected to in-plane biaxial tensile loadings. The goal is to achieve uniform failure in the gauge region of the specimen due to biaxial stress states and to reduce any premature failure outside the gauge region. Efficient finite element simulation in the commercial software LS-DYNA is used to identify the optimal geometric features.
Publisher: Elsevier BV
Date: 11-2020
Publisher: SAGE Publications
Date: 11-04-2022
DOI: 10.1177/10567895221089655
Abstract: This paper presents a systemic calibration methodology to efficiently simulate progressive damage evolution in four different pultruded glass fiber reinforced polymer (GFRP) composites using the strain-based COMposite DAMage Model (CODAM2) in the commercial finite element software LS-DYNA. In particular, Compact Tension (CT), scaled-up CT, and wide CT tests are simulated to find the best set of input parameters by considering four distinct indicators obtained from experimental and numerical load vs displacement data. By combining these indicators into a physically meaningful equivalent deviation value via a linear weighted-sum method, the results show that the most suited input damage variables yield physically accurate crack length predictions which underlines the robustness and accuracy of the proposed method. Furthermore, it is shown that the incorporation of bi-linear softening laws improves CODAM2 simulation results by up to 90%, however it also increases the number of parameters to be calibrated.
Publisher: Elsevier BV
Date: 02-2023
Publisher: Elsevier BV
Date: 06-2020
Publisher: SAGE Publications
Date: 28-07-2016
Abstract: An experimental and numerical study on low-velocity impact responses on [Ti/0/90] s hybrid titanium composite laminates (HTCLs) is presented. Different energy levels from 10 to 40 J are investigated using a drop-weight instrument and post-impact inspection. An explicit finite element implementation provides a detailed analysis of impact response in composite and titanium layers, respectively. It accounts for interfacial debonding, progressive failure in composite plies and elastic–plastic deformation in titanium. The main failure modes are experimentally and numerically found to be debonding between titanium and composite, matrix cracking and interlaminar delamination. The principal energy-absorbing mechanism is plastic dissipation of the two titanium sheets. The low cost numerical model is able to effectively predict the overall impact response and major failure modes with good accuracy.
Publisher: SAGE Publications
Date: 08-01-2023
DOI: 10.1177/00219983221149792
Abstract: This study presents a Discrete Element Method (DEM) for a meshfree progressive failure analysis of IM7/8552 carbon fibre reinforced polymer laminates at the macroscale. By implementing a cohesive contact model to describe progressive damage, experimental results from over-height compact tension (OCT) tests are used to calibrate the required input parameters in the DEM contact model. The simulation of various open-hole tension (OHT) test specimens validates the presented DEM model with minimal errors in strength predictions of up to 4%. Discrete Element Method results are directly compared to those obtained from finite element (FE) models. It is demonstrated that DEM is able to seemingly incorporate damage evolution leading to realistic macroscopic damage patterns, however the computational cost is increased by a factor of 100 compared to FE simulations.
Publisher: Elsevier BV
Date: 03-0009
Publisher: Elsevier BV
Date: 05-2022
Publisher: Springer Science and Business Media LLC
Date: 30-03-2022
DOI: 10.1186/S10086-022-02028-3
Abstract: Timber densification is a process that has been around since the early 1900s and is predominantly used to enhance the structural properties of timber. The process of densification provides the timber with a greater mechanical strength, hardness, abrasion resistance, and dimensional stability in comparison to its virgin counterparts. It alters the cellular structure of the timber through compression, chemical impregnation, or the combination of the two. This in turn closes the voids of the timber or fills the porosity of the cell wall structure, increasing the density of the timber and, therefore, changing its properties. Several processes are reported in literature which produce densified timber, considering the effect of various parameters, such as the compression ratio, and the temperature on the mechanical properties of the densified timber. This paper presents an overview of the current processes of timber densification and its corresponding effects. The material properties of densified timber, applications, and possible future directions are also explored, as the potential of this innovative material is still not fully realised.
Publisher: Elsevier BV
Date: 11-2021
Publisher: Elsevier BV
Date: 10-2022
Publisher: Elsevier BV
Date: 06-2021
Publisher: ASME International
Date: 09-08-2017
DOI: 10.1115/1.4037273
Abstract: Hybrid titanium composite laminates (HTCLs) combine the benefits of thin titanium sheets and fiber-reinforced polymer (FRP) composite laminates to design high performance light-weight materials with optimized impact resistance, fracture toughness, durability, and/or thermal performance. This paper starts with a detailed review of typical failure modes observed in HTCLs. The critical manufacturing process of thin grade II titanium sheets combined with HexPly G947/M18 carbon fiber-reinforced polymer laminates is described in detail. This includes the evaluation of titanium surface preparation techniques, which guarantee good adhesive bonding. A systematic experimental study of different HTCL configurations under tensile loading confirms that the major failure modes are debonding between the titanium sheet and the FRP laminate, matrix cracking in the 90 deg plies of the FRP laminate and interlaminar delamination. The results show that HTCLs made from woven carbon FRP plies show higher ultimate strengths and strain at breaks than HTCLs containing a cross-ply composite core made from unidirectional (UD) prepreg.
Publisher: Elsevier BV
Date: 07-2019
Publisher: Elsevier
Date: 2018
Publisher: Elsevier BV
Date: 07-2022
Publisher: Elsevier BV
Date: 10-2021
Publisher: Elsevier BV
Date: 05-2021
Publisher: Elsevier BV
Date: 08-2020
Publisher: World Scientific Pub Co Pte Ltd
Date: 08-04-2023
DOI: 10.1142/S0219876222410055
Abstract: Data-driven calibration techniques, consisting of theory-guided feed-forward neural networks with long short-term memory, have previously been developed to find suitable input parameters for the finite element simulation of progressive damage in fibre-reinforced composites subjected to compact tension and compact compression tests. The results of these machine learning-assisted calibration approaches are assessed in a range of virtual open-hole strength tests under tensile and compressive loadings as well as in low velocity impact tests. It is demonstrated that the calibrated material models with bi-linear softening are able to simulate the structural response qualitatively and quantitatively with a maximum error of 9[Formula: see text] with regards to experimentally measured open-hole strength values. Furthermore, the highly efficient models enable the virtual analysis of size effects as well as accurate force simulations in quasi-isotropic laminates under impact loading.
Publisher: Elsevier BV
Date: 12-2021
Publisher: DEStech Publications, Inc.
Date: 07-11-2018
DOI: 10.12783/ASC33/26071
Publisher: Springer Science and Business Media LLC
Date: 17-10-2022
DOI: 10.1007/S10853-022-07793-6
Abstract: With the increasing use of CubeSats in space exploration, the demand for reliable high-temperature shape memory alloys (HTSMA) continues to grow. A wide range of HTSMAs has been investigated over the past decade but finding suitable alloys by means of trial-and-error experiments is cumbersome and time-consuming. The present work uses a data-driven approach to identify NiTiHf alloys suitable for actuator applications in space. Seven machine learning (ML) models were evaluated, and the best fit model was selected to identify new alloy compositions with targeted transformation temperature (Ms), thermal hysteresis, and work output. Of the studied models, the K-nearest neighbouring ML model offers more reliable and accurate prediction in developing NiTiHf alloys with balanced functional properties and aids our existing understanding on compositional dependence of transformation temperature, thermal hysteresis and work output. For instance, the transformation temperature of NiTiHf alloys is more sensitive to Ni variation with increasing Hf content. A maximum Ms reduction rate of 6.12 °C per 0.01 at.% Ni is attained at 30 at.% Hf, and with a Ni content between 50 and 51 at.%. Graphical abstract
Publisher: SAGE Publications
Date: 22-12-2016
Abstract: Matrix cracking-induced delamination in composite laminates is qualitatively and quantitatively investigated in a finite element framework. The phantom node method is extended to incorporate breakable interfaces at transverse matrix crack tips. New user-defined element types in Abaqus improve the numerical stability in a geometrically nonlinear analysis. The new formulation allows for accurate prediction of matrix crack density and stiffness reduction in a number of composite laminates. Furthermore, the advanced phantom node method is able to simulate progressive matrix cracking-induced delamination with good accuracy.
Publisher: Elsevier BV
Date: 2019
Publisher: Elsevier BV
Date: 11-2023
Publisher: Elsevier BV
Date: 03-2017
Publisher: Elsevier BV
Date: 11-2020
Publisher: Elsevier BV
Date: 2021
Publisher: Elsevier BV
Date: 10-2023
Publisher: Elsevier
Date: 2018
No related grants have been discovered for Johannes Reiner.