• Steel and Composite Structures
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• 제23권3호
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• pp.303-315
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• 2017

This paper describes the finite element model for predicting the fundamental performance of embedded steel column base connections under monotonic and cyclic loading. Geometric and material nonlinearities were included in the proposed finite element model. Bauschinger and pinching effects were considered in the simulation of embedded column base connections under cyclic loading. The degradation of steel yield strength and accumulation of plastic damage can be well simulated. The accuracy of the finite element model is examined by comparing the predicted results with independent experimental dataset. It is demonstrated that the finite element model accurately predicts the behaviour and failure models of the embedded steel column base connections. The finite element model is extended to carry out evaluations and parametric studies. The investigated parameters include column embedded length, concrete strength, axial load and base plate thickness. Moreover, analytical models for predicting the initial stiffness and bending moment strength of the embedded column base connection were developed. The comparison between results from analytical models and those from experiments and finite element analysis proved the developed analytical model was accurate and conservative for design purposes.

• 대한기계학회논문집A
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• 제25권1호
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• pp.1-10
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• 2001

As computer power is increased, refined finite element models are employed for structural analysis. However, it is difficult and expensive to use refined models in the design stage. The refined models especially cause problems in the preliminary design where the design is frequently changed. Therefore, simplified models are needed. The simplification process is regarded as an empirical technique. Simplified and equivalent finite element model of a structure has been studied and used in the preliminary design. A general approach to establish the simplified and equivalent model is presented. The generated simple model has satisfactory correlation with the corresponding refined finite element model. An optimization method, the Goal Programming algorithm is used to make the simple model. The simplified model is used for the design change and the changed design is recovered onto the original design. The presented method was verified with three examples.

• 한국군사과학기술학회지
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• 제12권6호
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• pp.785-795
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• 2009

In this paper, new type of finite element models for the analysis of nonlinear beam bending are developed by using unconventional residual minimizing method to increase accuracy of finite element solutions and overcome some of computational drawbacks. Developing procedures of the new models are presented along with the comparison of the numerical results of existing beam bending models.

• Computers and Concrete
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• 제4권2호
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• pp.135-156
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• 2007

Three 3D nonlinear finite-element models are developed to study the behavior of concrete beams and plates with and without external reinforcement by fibre-reinforced plastic (FRP). All three models are formulated based upon the 3D theory of elasticity. The stress model is modified from the element developed by Ramtekkar, et al. (2002) to incorporate material nonlinearity in the formulation. Both transverse stress and displacement components are used as nodal degrees-of-freedom to ensure the continuity of both stress and displacement components between the elements. The displacement model uses only displacement components as nodal degrees-of-freedom. The transition model has both stress and displacement components as nodal degrees-of-freedom on one surface, and only displacement components as nodal degrees-of-freedom on the opposite surface. The transition model serves as a connector between the stress and the displacement models. The developed models are validated by comparing the results of the analyses with an existing experimental result. Parametric studies of the effects of the externally reinforced FRP on the load capacity of reinforced concrete (RC) beams and concrete plates are performed to demonstrate the practicality and the efficiency of the proposed models.

• 한국정밀공학회지
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• 제22권10호
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• pp.202-209
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• 2005

In this study, two dimensional and three dimensional finite element models of lower first premolar were analyzed. The mandibular specimen including a premolar was obtained from a cadaver and scanned with micro-CT. Finite element method models were reconstructed from CT images at mid-sagittal plane of the tooth. Most studies have used a wide range of value(0.07${\~}$1000MPa) for elastic modulus of periodontal ligament. The elastic modulus of the periodontal ligament was analyzed by finite element method and compared with that of experiment model. This study indicated that the model without pulp was more suitable than that with pulp in two dimensional finite element analysis.

• Structural Engineering and Mechanics
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• 제7권4호
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• pp.377-386
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• 1999

The stress distribution in a symmetrically laminated composite plate subjected to in-plane compression are evaluated using finite element analysis. Six different finite element models are created for the study of stresses in the plate after buckling. Two finite element modelling approaches are adopted to obtain the stress distribution. The first approach starts with a full model of shell elements from which sub-models of solid elements are spin-off The second approach adopts a full model of solid elements at the beginning from which sub-models of solid elements are created. All sub-models have either 1-element thickness or 14-element thickness. Both techniques show high interlaminar direct and shear stresses at the free edges. The study also provides vital information of the distribution of all components of stresses along the unloaded edges in length direction and also in the thickness direction of the plate.

• 대한치과보철학회지
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• 제39권6호
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• pp.611-624
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• 2001

A precise fit of the implant prosthesis is one of the most important factors in preventing mechanical complications. To analyze the degree of the misfit of implant prosthesis, a modal testing experiment was accomplished. And. to interpret the modal testing analysis mathematically, three-dimensional finite element models were established. In the experimental modal testing analysis, with a laser displacement meter, FFT analyzer, impact hammer, etc., natural frequencies of the models with various degree of prosthesis fit were determined after the frequency response function were calculated. In the finite element analysis, the natural frequencies and mode shapes of the models which simulated those of experimental modal testing were computed. The results were as follows: 1. Natural frequencies of the prosthesis-abutment were related to the contact state between components. 2. In the modal testing experiment, the natural frequencies increased from $50{\mu}m$ to $200{\mu}m$ gap and reached a plateau. 3. In the finite element analysis, the natural frequencies decreased gradually according to the in crease of the gap size. 4. In the finite element analysis, the mode shapes of model 1 with misfitting prosthesis showed different patterns from those without misfitting prosthesis. 5. The devices including a laser displacement meter used in this study were useful for measuring the natural frequencies of an implant prosthesis which had various degrees of fit.

• Steel and Composite Structures
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• 제31권2호
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• pp.173-185
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• 2019

This paper presents experimental and numerical investigations of aluminum tubular members subjected to combined bending and web crippling. A series of tests was performed on square hollow sections (SHS) fabricated by extrusion using 6061-T6 heat-treated aluminum alloy. Different specimen lengths were tested to obtain the interaction relationship between moment and concentrated load. The non-linear finite element models were developed and verified against the experimental results obtained in this study and test data from existing literature for aluminum tubular sections subjected to pure bending, pure web crippling, and combined bending and web crippling. Geometric and material non-linearities were included in the finite element models. The finite element models closely predicted the strengths and failure modes of the tested specimens. Hence, the models were used for an extensive parametric study of cross-section geometries, and the web slenderness values ranged from 6.0 to 86.2. The combined bending and web crippling test results and strengths predicted from the finite element analysis were compared with the design strengths obtained using the current American Specification, Australian/New Zealand Standard and European Code for aluminum structures. The findings suggest that the current specifications are either quite conservative or unconservative for aluminum square hollow sections subjected to combined bending and web crippling. Hence, a bending and web crippling interaction equation for aluminum square hollow section specimens is proposed in this paper.

• Computers and Concrete
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• 제15권2호
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• pp.279-304
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• 2015

In this study, reliability analyses of steel fiber reinforced concrete (SFRC) corbels based on stochastic finite element were performed for the first time in literature. Prior to stochastic finite element analysis, an experimental database of 84 sfrc corbels was gathered from literature. These sfrc corbels were modeled by a special finite element program. Results of experimental studies and finite element analysis were compared and found to be very close to each other. Furthermore experimental crack patterns of corbel were compared with finite element crack patterns and were observed to be quite similar. After verification of the finite element models, stochastic finite element analyses were implemented by a specialized finite element module. As a result of stochastic finite element analysis, appropriate probability distribution functions (PDF's) were proposed. Finally, coefficient of variation, bias and strength reduction (resistance) factors were proposed for sfrc corbels as a consequence of stochastic based reliability analysis.

• 한국생산제조학회지
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• 제22권3호
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• pp.380-387
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• 2013

In this study, two finite element (FE) models were developed to evaluate the thermal characteristics of a feeding axis of a CNC lathe. One was used for analysis of heat transfer to identify the temperature distribution of the feeding axis and then, the other was used for analysis of thermal deformation to evaluate its structural behavior based on the temperature distribution. The FE models were based on the test standard for the axial thermal displacement. The feeding velocity was composed of three steps: the ascending, constant, and descending velocities. Therefore, the heat generation and convection coefficient were calculated for each velocity and applied to the thermal FE model. The convection coefficient for the ball screw rotation was based on an experimental equation. The result of the analytical thermal displacement was compared with that of the experimental displacement to verify the finite element models.