STUDI NUMERIK PENGARUH PEREKAT DAN GEOMETRI SPESIMEN TERHADAP PERILAKU BUCKLING DARI STRUKTUR HONEYCOMB SANDWICH PADA PEMBEBANAN TEKAN

Struktur sandwich adalah material hibrid dimana inti yang ringan direkatkan dengan kulit yang berkakuan tinggi. Pada industri otomotif dan dirgantara, struktur honeycomb aluminium umum digunakan sebagai bahan penyerap energi. Ketika diberi beban tekan, sel-sel heksagonal pada inti honeycomb mengalami buckling dan berdeformasi plastis secara seragam, sehingga mengurangi beban yang ditransfer ke struktur utama. Berbagai kajian secara eksperimental, analitikal maupun numerikal telah dilakukan untuk menjelaskan perilaku mekanik material ini. Namun, kajian yang menghubungkan jenis adhesif dan tinggi inti terhadap perilaku buckling masih jarang ditemukan. Pada kajian ini, perilaku buckling dalam arah out-of-plane dari struktur honeycomb sandwich aluminium dikaji dengan menggunakan metode elemen hingga. Struktur honeycomb sandwich aluminium ditekan secara virtual mulai dari zona elastik awal hingga ke keadaan hancur sepenuhnya menggunakan pendekatan pemodelan analisis non-linear eksplisit. Pendekatan pemodelan analisis linear implisit juga digunakan. Setelah hasil simulasi berhasil divalidasi, dilakukan analisis yang menghubungkan bagaimana pengaruh variasi adhesif dan tinggi inti terhadap gaya critical buckling, gaya average crush load dan energi yang dapat diserap. Pada struktur honeycomb sandwich aluminium, kemampuan penyerapan energi meningkat seiring meningkatnya tinggi inti namun disertai menurunnya kekakuannya terhadap buckling, sementara variasi adhesif menunjukkan tidak adanya perubahan pada gaya critical buckling, gaya average crush load maupun kemampuan penyerapan energi secara signifikan

Uncertainty analysis of varied meshes of a finite element model using Monte Carlo simulation

Purpose – Advanced computational methods help to solve complex engineering problems via finite-element simulation. However, uncertainties during the process occurred due to the nature of geometry, material properties, loading, and boundary conditions. These inaccuracies affect the accuracy of results obtained from the analysis. This paper aims to analyse the uncertainty parameters of a finite element model in Excel-Visual Basic Application (VBA) by applying a random simulation method. Design/methodology/approach – This study focuses on a finite element model with a different mesh. Young’s Modulus, E, Poisson’s ratio, and load, L are the uncertainty input parameters considered random variables. Findings – Results obtained proved that the finite element model with the most nodes and elements has better solution convergence. Originality/value – Random simulation method is a tool to perform uncertainty analysis of a finite element model

Numerical Analysis of structural batteries response with the presence of uncertainty

In order to further reduce oil dependence and world pollution, there’s growing interest in embedding batteries such as Li-Po batteries within vehicle components. The implementation of structural batteries is believed to be the next promising approach for next-generation hybrid and electric vehicles. The proposed research is devoted to the uncertainty analysis of structural battery behavior under various parameters. To help with the analysis, a dedicated algorithm based on an elimination approach to solve numerical problems with uncertain parameters is successfully developed using Visual Basic. The Constant Strain Triangle element with linear elastic behavior is used as a structural model to simplify the model. Uncertainty of the material properties and loading are modeled as Fuzzy Random Variables. In evaluating the influence of the uncertainty parameters, Interval Monte Carlo Simulation and the interval finite element method are used to compute the bounds of the structure behavior. Simulation results between the Interval Monte Carlo and Deterministic are compared to evaluate the significance of the uncertainty factor influences. It is shown that the structural batteries that can be considered safe based on deterministic parameters may be unsafe if the uncertainty parameters are considered. The proposed approach could detect the results that are not necessarily detected through deterministic means. By producing a broader result, further prevention and consideration can be made to avoid catastrophic events

Uncertainty Prediction Output of a Finite Element Model (FEM) Using Surrogate Modelling Approach

Additive Manufacturing (AM) is a manufacturing approach that can build a three-dimensional object from a computer- aided design model by adding material layer by layer. This method has gained popularity due to its capability to manufacture a product with complex geometries. However, uncertainties exist in its structure as it involves the material properties and geometry parts. A computational approach via Finite Element Method (FEM) is an alternative to overcome these uncertainties. Due to its high computational effort and time consumption, the Machine Learning approach via Surrogate Modelling is another method to produce the output of the simulation results. Surrogate Modelling can generate output with an R2 value of 0.98 intervals when compared with the FEM results. The results demonstrate the potential of Surrogate Modelling to run FEM output via sufficient training data input

Uncertainty Factors of a Finite Element Model using the Fuzzy Analysis Method

The recent advancement in manufacturing technology in the automotive and aerospace sectors has led to the invention of advanced structured material, which is lightweight and a complex geometry model that can be manufactured. As it is related to human safety and hazards, the need for uncertainty analysis in a structure before and after a manufacturing process is a primary concern. Thus, this paper analyzes the uncertainty parameters of a meshed finite element model in the geometry, boundary condition, load, and material properties. An uncertainty analysis numerical tool, the fuzzy analysis method, is applied in Excel-VBA as the simulation platform. Each uncertainty parameter is in a range of numbers, with a maximum and minimum value as the limit. The α-cuts determine the fuzzy analysis output on the membership function. The deterministic value of the variable is implemented for comparison purposes. The simulation result for the von-Mises stress analysis has significantly impacted the uncertainty analysis as its curve has surpassed the yield strength limit of the material. The simulation output for the displacement has a more considerable uncertainty dispersion when compared to the other results. This study helps to find a better security margin of a structure for its sustainability in the future