Papers by Keyword: Finite Element Model (FEM)

Abstract: The purpose of this work is to study a new composite material consisting of polyurethane (PU) resin and carbon fiber fabric. This PU resin is superior in impact, viscosity, low curing temperature, and short curing time. If this resin is combined with fiber fabric by vacuum assisted resin transfer method, the fabrication time will be short. Since it is a braided composite, it’s important to have a model to predict the elastic constants for different braid angels. To predict the elastic constants including Young’s modulus, shear modulus, and Poisson’s ratio, a finite element model is established. In this model a braided layer is treated as two uni-directional layers. Then, the elastic constants of this composite with different braid angels are estimated. After that, the composites with different braid angels are fabricated and tested to obtain the elastic constants, and the comparison with the finite element results is made. The results indicate that the agreement is very good for the Young’s modulus. For the Poisson’s ratio, the difference between the prediction and the measurement is reasonable. From the comparison, it can be concluded that the finite element model is good. Then, this model is used to predict all in-plane elastic constants for arbitrary braid angles.

Abstract: Using porous bioceramics became recently an alternative approach to increase bone density which is a key factor for successful dental implant application. These novel biomaterials should substitute missing natural trabecular structures in terms of material strength as well as deformation characteristics. However, mechanical behavior of these materials used as bone fillers are still in question. This problem is made more difficult by the fact that bone structure itself exhibits a complex mechanical behavior which is still in question as well and, therefore, appropriate analytical criteria should to be established. The purpose of this paper is to determine typical mechanical behavior of trabecular structure of mandibular cancellous bone using computational simulations which can serve as a basis for establishing such criteria. For this purpose, four bone specimens of various bone density were μCT-scanned and high-level finite element models including detailed trabecular structure were created on their basis to analyze relevant mechanical quantities for various loadings in terms of bone density and various histomorphometric parameters.

Abstract: To better understand response or fracture conditions of the ceramic foam materials to the mechanical loading, a finite element (FE) analysis of these structures has to be employed. The cellular structure of foams can be modelled either using a detailed realistic FE model based on the computer tomography scans or by using of simplified, beam element based, models. Nevertheless a main drawback of the realistic foam modelling consists in its high demandingness on computational resources. Therefore, simplified models are welcome substitutions (at least for analysis of the global mechanical foam response). The regular foam structure, based e.g. on Kelvin cells, is simple from the modelling point of view, but it doesn´t exactly capture the fully random character of the real foam structures and corresponding response to the external load. Definition of the random beam foam structure (respecting the real cell shapes and their distribution within volume), can thus improve this deficiency. The main aim of this work is thus to compare these different modelling approaches and quantify the influence of the foam irregularity on the response of ceramic foams to external (tensile) loading for various model sizes.

Abstract: This study is aimed to investigate the seismic behavior of the freestanding dry storage cask for spent fuel, several shaking table tests were conducted using a scaled cask model for a real assessment of the characteristics of the seismic response of the cask. First, the harmonic excitation test on the pedestal of the cask was performed to estimate the friction coefficient at the interface between the cask and the pad according to the sliding acceleration response of the pedestal. Then, tests for the seismic response of the cask were conducted for two different setups, the vertical cylindrical concrete cask (VCC) and the concrete cask with an add-on shield which has a square pedestal (VCC+AOS), respectively, using the artificial earthquakes compatible to the design spectrum. In order to verify the often-used analysis method for the seismic response of the cask in engineering practice, the explicit finite element software LS-DYNA was adopted to generate the finite element model of the scale cask with the cask/pad interface modeled by Coulomb’s law of friction and to simulate the shaking table tests. Results indicate that the utilized method gave reasonable cask responses if the variation of the friction coefficient at the cask/pad interface was small during the sliding process.

Abstract: The Interfacial Transition Zone (ITZ) between two basic materials having differentiations in their mechanical properties has always been intriguing. The stiffness disparities between the two will result in a very distinctive area, the interface. Cement based components such as mortar and concrete consist of the cement paste and aggregates, with the ITZ at the perimeter. When compared to the cement paste, this ITZ has a higher porosity with a dissimilar crystal formation. The resulting area therefore becomes the weak link in concrete. A Finite Element Model (FEM) was developed to construct the load-displacement behavior of a single inclusion specimen and to study the crack propagation within the ITZ. The ITZ was modeled as a linkage element having a double spring, perpendicular and parallel to the ITZ surface. The individual stiffness behavior of these springs was obtained from laboratory-tested specimens. Non-linearity was generated by evaluating the principal stresses and strains at Gauss points, while the CEB-FIB 2010 code was used for the constitutive material behavior of the mortar. Iteration is conducted by the arc-length method developed by Riks-Wempners. The load-displacement curves resulting from the FEM were validated with laboratory tested specimens to compare its effectiveness and assess the correctness of the model.

Abstract: A current challenge for researchers is the design and implementation of an effective vibration control method that reduces vibration transmission from vehicle structures such as aircraft. This challenge has arisen due to the modern trend of utilizing lightweight thin panels in aircraft structural design, which have the potential to contribute towards significant vibration in the structures. In order to reduce structural vibration, one of the common approaches is considering vibration neutralizer system attached to the structure. In this study, a vibration neutralizer is developed in a small scale size. The effectiveness of attached vibration neutralizers on a thin plate are investigated through experimental study. Prior to the experiment, a finite element analysis of Solidworks® and analytical modelling of Matlab® are produced in order to determine the structural dynamic response of the thin plate such as the natural frequency and mode shapes. The preliminary results of finite element analysis demonstrate that the first four natural frequency of clamped plate are 48Hz, 121Hz, 194Hz and 242Hz, and these results are in agreement with the plate’s analytical equations. However, there are slight discrepancies in the experiment result due to noise and error occurred during the set up. In the later stage, the experimental works of thin plate are performed with attached vibration neutralizer. Result shows that the attachment of vibration neutralizer produces better outcome, which is about 41% vibration reduction. It is expected that by adding more vibration neutralizer to the structure, the vibration attenuation of thin plate can be significant.

Abstract: The article demonstrates one of the ways to reduce uneven load distribution along the width of the gear wheels which can be used in place of expensive modifications of the tooth flanks (crowning). This can be achieved by appropriate selection of the shape of the gear wheels for example the disk shape. The presented numerical example illustrates the above possibility taking into account deformability of the wheel body.

Abstract: In order to study the performance of lightweight energy-saving composite floor, the finite element models of composite floor were established, which was based on the composite floor specimens test research. The finite element models were verified rationally and correctly in the paper, through compared with the composite floor test results. The finite element model can be used to analyze the load-bearing capacity of composite floor. Various influencing factors of composite floor with simply supported end were analyzed, such as the span of self-tapping screw, the diameter of self-tapping screw, the strength of thin panel and the elastic modulus of thin panel, etc. The results show that the load-bearing capacity of composite floor increases with the increase of the number of self-tapping screw, the diameter of self-tapping screw, the strength of thin panel and the elastic modulus of thin panel, etc. The load-bearing capacity calculate formula of composite floor was proposed.

Abstract: With the development of advanced composites technology, composites instead of traditional aluminum alloy, will be widely used to build full-size aircraft windshield structure in the aviation field. The finite element model of commercial aircraft composite windshield is established in the environment of Msc.Patran / Nastran. And based on Tasi-Wu failure criterion, the strength of windshield structure under typical load pressure is predicted and analyzed during failure processes. It shows that composite windshield can work better through rational design according to the analysis result.

Abstract: The finite element analysis of PCP involves three nonlinear of geometry, material and contact, and the load of PCP is diversity, leading to it difficult to establish the finite element model and calculate by finite method. This article takes GLB120-27 as an example, to establish 3D solid model of PCP by using SolidWorks; to determine M-R model constant of stator rubber by using the data of uniaxial tensile test: to separate the seal band from the stator chamber by using Boolean operation and set up contact pairs, to achieve the correct simulation of stator chamber fluid pressure; to correctly simulate the interference fit between stator and rotor through setting correlation parameters; to establish 3D finite element analysis model and verify the correctness by using the experiment data of hydraulic characteristics of PCP.