scholarly journals Thermal Crack Analysis Based on Practical 3-D FEM Analysis Model.

1996 ◽  
pp. 95-104
Author(s):  
Hiroaki Morimoto ◽  
Wataru Koyanagi
Keyword(s):  
Fem Analysis ◽  
Thermal Crack ◽  
Analysis Model ◽  
Crack Analysis

Damage Evolution of the Interphase on C/SiC Composites with CZM Method

2012 ◽  
Vol 166-169 ◽  
pp. 2847-2850
Author(s):  
Yan Jun Chang ◽  
Zhuo Li ◽  
Ke Shi Zhang
Keyword(s):  
Residual Stress ◽  
Damage Evolution ◽  
Fem Analysis ◽  
Matrix Crack ◽  
Thermal Residual Stress ◽  
Analysis Model ◽  
Initial Matrix ◽  
Thermal Residual Stresses ◽  
Initiation And Propagation ◽  
Sic Composites

Considering thermal residual stress and initial matrix crack, the cylinder FEM analysis model for C/SiC tow was established. The cohesive element and damage criterions were introduced to simulation the initiation and propagation of interphase crack processes of C/SiC composites. The thermal residual stresses release with the initial matrix crack and the cracking on interphase. The interphase crack length was dominated by the performance of interphase. Analysis demonstrated that the CZM model can simulate well the thermal residual stress and the delamination of the interphase.

ANALYSIS MODEL FOR SHAPE MEMORY EFFECT IN Ti-Ni SYSTEM ALLOY OF RING CONFIGURATION

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3951-3956
Author(s):  
KEISUKE OKITA ◽  
NAGATOSHI OKABE ◽  
TOMOYUKI SATOH ◽  
KAZUNARI UCHIDA
Keyword(s):  
Shape Memory ◽  
Axial Stress ◽  
Volumetric Strain ◽  
Fem Analysis ◽  
Modeling Method ◽  
Test Results ◽  
Analysis Model ◽  
Fem Modeling ◽  
Ring Configuration ◽  
Shape Memory Effects

Shape memory alloys are well known to be used as a ring element for connect coupling two pipes in various fields. In the case of structural and functional designs for a coupling ring of shape memory alloy, we have considered the shape memory effects in multi-axial stress and strain using volumetric strain in each element, so as to make FEM analysis more effective for optimizing the shape and the amount of pre-deformation. Using some uni-axial fundamental test results, as property parameters for FEM, the modeling method simulating the deformation behavior of a coupling ring has been eveloped in order to optimize the configuration and size of a coupling ring. The validity of this FEM modeling method was confirmed by verification experiments.

Fabrication of a piezoelectrically driven micropositioning 3-DOF stage with elastic body using a multi-material 3D printer

2020 ◽  
Vol 26 (9) ◽  
pp. 1579-1591
Author(s):  
Sang-Woo Baek ◽  
Nahm-Gyoo Cho ◽  
Dong-Hyeok Lee
Keyword(s):  
Elastic Body ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Fem Analysis ◽  
Experimental Results ◽  
Analysis Model ◽  
Content Type ◽  
Vision Measurement ◽  
Conventional Material ◽  
Single Material

Purpose This paper aims to propose a method for manufacturing multi-material monolithic structures with flexible materials to construct the elastic body by using a dual-nozzle three-dimensional printer to develop a piezoelectric (PZT)-driven micropositioning stage with three degrees of freedom (3-DOF) and flexure hinges. Design/methodology/approach Polylactic acid (PLA) and nylon were used for the lever structure’s frame and flexure hinge, respectively. Additionally, the stage consisted of three PZT actuators for fine movement in the nanometer scale in 3-DOF (x, y and θ-directions). For the design of the stage, the kinematic analysis model and the finite element method (FEM) analysis was undertaken for comparing between PLA with nylon (multi-material), PLA (single material) and aluminum (conventional-material). In addition, two verification experiments were implemented for the fabricated prototype stage. First, to evaluate various assessments (lever ratio, hysteresis, coupling error and resolution), a measurement is carried out using the three capacitive sensors. Then, a two-camera-vision measurement experiment was performed to verify the displacement and lever ratio over the full-scale working range of the fabricated positioning stage, and the results from the experimentation and the FEM analysis were compared. Findings The authors confirmed enhancements in the properties of the lever structure frame, which requires stiffness and of the hinge, which requires flexibility for elastic deformation. Comparing FEM analysis and experimental results, although the performance as shown by experimental results was lower: the maximum difference being 3.4% within the end-point working range; this difference was sufficient to be a plausible alternative for the aluminum-based stage. Originality/value Multi-material monolithic-structure fabrication has an effective advantage in improving the performance of the stage, by using a combination of materials capable of reinforcing the desired characteristics in the necessary parts. It was verified that the fabricated stage can substitute the aluminum-based stage and can achieve a higher performance than single-material stages. Thus, precise-positioning stages can be manufactured in many kinds of structures with various properties and contribute to weight reduction and low costs for application equipment.

scholarly journals Enriched degree of freedom locking in crack analysis using the extended finite element method

2019 ◽  
Vol 11 (6) ◽  
pp. 168781401985979
Author(s):  
Han-Soo Kim ◽  
Geon-Hyeong Kim
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Extended Finite Element Method ◽  
Degree Of Freedom ◽  
Analysis Model ◽  
Extended Finite Element ◽  
Simple Method ◽  
Numerical Examples ◽  
Crack Analysis ◽  
Element Method

In this article, the enriched degree of freedom locking that can occur in a crack analysis with the extended finite element method is described. The discontinuous displacement field formulated by the enriched degree of freedom in the extended finite element method does not activate due to the enriched degree of freedom locking. Using the phantom node method, the occurrence of locking when two adjacent elements are simultaneously cracked in a loading step was verified. Two adjacent cracks can be determined to have developed simultaneously when an analysis model reveals a relatively uniform stress distribution on two adjacent elements. Numerical examples of a simply tensioned bar and a reinforced concrete beam are presented to demonstrate the erroneous analysis result due to the enriched degree of freedom locking. As a simple method to circumvent the enriched degree of freedom locking, the tensile strength of the neighboring elements was slightly increased in the numerical examples, and the effectiveness of the method was demonstrated. The proposed method is simple and easy for practicing engineers, and it can be easily applied to the three-dimensional crack propagation analysis.

Experiment Study and Nonlinear Analysis of a New Skip-Floor Staggered Shear Wall Structure for High-Rise Buildings

2013 ◽  
Vol 351-352 ◽  
pp. 131-137
Author(s):  
Jian Xin Liu ◽  
Hong Nan Wang ◽  
Pei Li ◽  
Mei Chun Zhu
Keyword(s):  
Nonlinear Analysis ◽  
Fem Analysis ◽  
Shear Wall ◽  
Economic Benefits ◽  
Wall Structure ◽  
Structural System ◽  
Analysis Model ◽  
Experiment Study ◽  
Nonlinear Fem ◽  
Seismic Force

A new tall building structure is presented -- skip-floor staggered shear wall structure. According to the result of nonlinear analysis and experiment study, this new structural system has good economic benefits and better structural behavior. In order to study its spatial nonlinear properties, based on a 3D nonlinear FEM analysis model, the 3D seismic nonlinear analysis is provided by considering both spatial effect and influence of slab and connecting beam. It shows, compared with traditional coupled shear wall structure, the skip-floor staggered shear wall structure has superiority in many respects, such as providing bigger space and lateral stiffness, reducing seismic force, etc. Therefore, this new structural system has wide applications.

Investigations on Crack-Like Leaks in Piping

2015 ◽  
Author(s):  
Christoph Bläsius ◽  
Klaus Heckmann ◽  
Jürgen Sievers
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Fem Analysis ◽  
Analysis Model ◽  
Safety Standard ◽  
System Pressure ◽  
Surge Line ◽  
Cooling Loop ◽  
Simplified Calculation ◽  
Leak Before Break

Methods to demonstrate break preclusion for pressure retaining components in nuclear power plants are summarized in the newly developed German safety standard KTA 3206, especially the requirements for the leak-before-break assessment of crack-like leaks. In this context numerical and simplified calculation methods for both the leak opening area and fluid flow rates of crack-like leaks were examined and validated on selected experiments. Second topic of the paper is an accident analysis for a postulated leak in form of a through-wall crack in the pressurizer surge line (SL) of a German PWR Konvoi type. The initial size of the leak as well as the changing size depending on system pressure and temperature during the postulated leak accident was calculated with a FEM analysis model of a cooling loop. The reduction of the leak area amounts in the examined transient to ca. 25 % after 1 h and leads also to an approximately 23 % smaller leak rate. These results depend on the assumed position of the leak and on the initial leak size. Therefore, the results of accident analyses due to postulated leaks can be influenced by the change of the leak size during the course of the accident.

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