scholarly journals Solid Model Generation for Digitized Organic Bodies via T-Splines

Heritage ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 606-636
Author(s):  
Luigi Barazzetti
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Point Clouds ◽  
Solid Model ◽  
Model Generation ◽  
Element Analysis ◽  
Mesh Resolution ◽  
The Difference ◽  
Preliminary Extraction ◽  
Solid Bodies

This paper presents a workflow for B-rep solid model generation of organic objects using T-splines constructed with quad-meshes. The aim is the creation of geometrically and topologically consistent B-rep solid models of heritage objects featuring organic shapes, which can be used in numerical simulation based on meshless finite element analysis. Point clouds and closed triangular meshes are converted into B-rep solids with a multi-step procedure based on the preliminary extraction of quadrilateral meshes, which are used to produce T-splines. Evaluation of metric quality is carried out to quantify the difference between the final solid and input datasets. A coarse-to-fine approach can also be exploited by varying the quad-mesh resolution to preserve the level of details captured during the digitization process. Finally, meshless finite element analysis can be run with the produced solid bodies. Results for both simulated and real heritage objects are illustrated and discussed.

Onvex Partitioning Approach for the Construction of Solid Model From Measured Point Data

1998 ◽  
Author(s):  
V. Devaraja Holla ◽  
S. S. Krishnan ◽  
B. Gurumoorthy
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Solid Model ◽  
Planar Surface ◽  
Element Analysis ◽  
Final Model ◽  
Convex Partition ◽  
Point Data ◽  
Definition Of ◽  
The Individual

Abstract This paper describes an algorithm for the construction of solid model from measured point data using Convex Partitioning approach. Convex Partitioning approach is based on the idea that any non-convex body can be viewed as a combination of several convex pieces. The input constitutes a set or cluster of points, measured on each face of the object, which is obtained by scanning the part. Points in each cluster are used to fit a plane or a non-planar surface depending upon the type of face. Partitioning is done along the planes till one gets all the convex pieces. The individual convex pieces are then combined together to get the final model of the object. The definition of convex partition is relaxed for objects having curved faces, to be an object with all its edges convex. Apart from allowing the construction of solid model from measured point data, the output (convex pieces) obtained from this approach is useful in planning for rapid prototyping and feature suppression in finite element analysis.

A Comparative Study on Mechanical Behavior of Pipe-Socket Threaded Joints With Taper-Taper Threads and Taper-Parallel Threads Combinations by Finite Element Analysis and Experiments

2018 ◽  
Author(s):  
Satoshi Nagata ◽  
Shinichi Fujita ◽  
Toshiyuki Sawa
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Service Condition ◽  
Internal Thread ◽  
Element Analysis ◽  
Strain Pattern ◽  
External Thread ◽  
Thread Length ◽  
The Difference

There are two types of combination between external and internal threads used in threaded pipe connections for pressure piping specified in industrial standards like JIS as well as ISO. One is the combination that taper external thread of pipe is engaged with taper internal thread of a fitting. The other is that taper external thread of pipe is engaged with parallel internal thread of a fitting. Taper thread is always used for external thread outside the pipe wall. Both taper thread and parallel one are applicable to internal thread inside the fittings. This paper evaluates the mechanical behaviors of threaded pipe-socket joints (or pipe-coupling joints) and the difference due to the thread type combinations by means of axisymmetric finite element analysis for 3/4” and 3” joints. The analysis shows that the taper-taper threads combination establishes the full-length contact over the engaged threads but the taper-parallel has only a pair of threads in contact at the 1st engaged thread from the end of socket, and the difference results in the different behaviors of the joints. Stress and strain pattern also completely differ due to the difference in the engaged thread length. No significant effect of the size has been found in the present analysis for 3/4”and 3” joints. Experimental tightening tests and pressure leak tests have also been carried out for 3/4” and 3” joints with taper-taper threads combination. The measured experimental stress for 3/4” joints has shown an agreement with the simulated one fairly well. The pressure leak tests have demonstrated that the taper-taper threaded pipe-socket joints can hold internal pressure without leakage without using thread seal tape or jointing compound under low-pressure service condition. The 3/4” joints have started leaking at 1–4MPaG of internal pressure. The 3” joints haven’t shown leakage even at 6MPaG of internal pressure applied.

scholarly journals Dynamic Response of a Laminated Plate With Friction Damping

1985 ◽  
Vol 107 (4) ◽  
pp. 375-377 ◽  
Author(s):  
Shen Zhong Han
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Resonant Frequency ◽  
Laminated Plates ◽  
Laminated Plate ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Solid Plate ◽  
Sandwich Type ◽  
The Difference

A sandwich-type plate with metal facings and felt core, fastened by bolts, was studied using both test and finite-element analysis. This type of plate is cheap, light, damping-effective and without pollution; therefore, it is widely used in astronautical engineering. The tests were conducted for different felt thicknesses, bolt numbers, and fastening forces. The results show that the damping depends on friction between the plates and the felt. As compared with an identical stiffness solid plate, the damping of laminated plates can be increased up to 30 times. A mesh with rectangular elements was adopted in the finite-element analysis. In accordance with the slipping mechanism, a rectangular plate clamped on one edge was analyzed with the foregoing elements to determine the resonant frequency and the damping. The difference between the calculated and tested results was within 5 percent for the resonant frequency.

Finite Element Analysis and Design of a Horizontal Tank on Saddle Supports

2002 ◽  
Author(s):  
Afewerki H. Birhane ◽  
Yogeshwar Hari
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Code Design ◽  
Element Analysis ◽  
Analysis And Design ◽  
Finite Element Software ◽  
Asme Code ◽  
Design Function ◽  
Horizontal Tank ◽  
The Difference

The objective of this paper is to design and analyze a horizontal tank on saddle supports. The horizontal vessel is to store various chemicals used in today’s industry. The over all dimensions of the horizontal vessel are determined from the capacity of the stored chemicals. These dimensions are first determined. The design function is performed using the ASME Code Sec VIII Div 1. The horizontal tank design is broken up into (a) shell design, (b) two elliptical heads and (c) two saddle supports. The designed dimensions are used to recalculate the stresses for the horizontal vessel. The dimensioned horizontal vessel with saddle supports and the saddle support structure is modeled using STAAD III finite element software. The stresses from the finite element software are compared with the stresses obtained from calculated stresses by ASME Code Sec VIII Div 1 and L. P. Zick’s analysis printed in 1951. The difference in the stress value is explained. This paper’s main objective is to compare the code design to the finite element analysis. The design is found to be safe for the specific configuration considered.

Distortion Simulation of Unsymmetrical Composite Laminates Using the Finite Element Analysis Method

2007 ◽  
Vol 546-549 ◽  
pp. 1563-1566
Author(s):  
Min Li ◽  
Bao Yan Zhang ◽  
Xiang Bao Chen
Keyword(s):  
Experimental Data ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Composite Laminates ◽  
Shell Element ◽  
Element Analysis ◽  
Unsymmetric Laminates ◽  
The Finite Element Analysis ◽  
Simulation Results ◽  
The Difference

Unsymmetric composite laminates were benefit to reducing the structure weight of some aircrafts. However, the cured unsymmetric laminates showed distortion at room temperature. Therefore, predicting the deformation before using the unsymmetrical composite is very important. In this study an attempt was made to predict the shapes of some unsymmetric cross-ply laminates using the finite element analysis (FEA). The bilinear shell-element was adopted in the process. Then the simulation results were compared with the experimental data. The studies we had performed showed that the theoretical calculation agreed well with the experimental results, the predicted shapes were similar to the real laminates, and the difference between the calculated maximum deflections and the experimental data were less than 5%. Hence the FEA method was suitable for predicting the warpage of unsymmetric laminates. The error analysis showed that the simulation results were very sensitive to the lamina thickness, 2 α and (T.

An Evaluation Index for Estimating Defeaturing-Induced Impacts on Finite Element Analysis

2009 ◽  
Author(s):  
Jianguo Tang ◽  
Shuming Gao ◽  
Hongwei Lin ◽  
Yusheng Liu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fe Analysis ◽  
Evaluation Index ◽  
Reciprocal Theorem ◽  
Element Analysis ◽  
Efficient Calculation ◽  
Practical Evaluation ◽  
The Difference ◽  
The Reciprocal Theorem

Defeaturing is a popular CAD/CAE simplification technique. However, defeaturing inevitably leads to errors that can not be effectively evaluated yet during a FE (Finite Element) analysis. In this paper, a novel evaluation index based on the reciprocal theorem is proposed to effectively and efficiently estimate defeaturing-induced impacts on FE analysis. Instead of using the difference of strain energy, the proposed evaluation index uses the difference of work to quantify the defeaturing-induced impacts on FE analysis so that it is not only effective but also can be efficiently calculated. In order for an efficient calculation of the evaluation index, a practical evaluation index is further derived from the proposed theoretical index, and its calculation method is given. The practical evaluation index has been applied to FE static computation of linear elastic structures. Therefore, we are able to adapt the simplification of a model according to a desired accuracy of the analysis results.

Prediction of Closure Bolt Loads in Small Pressure Vessels: NUREG/CR-6007 vs. Detailed Finite Element Analysis

2010 ◽  
Author(s):  
Charles A. McKeel
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Small Diameter ◽  
Pressure Vessels ◽  
Element Analysis ◽  
Containment Vessel ◽  
Fea Model ◽  
Significant Difference ◽  
Load Increase ◽  
The Difference

Closure bolt loads in a flanged cylindrical containment vessel under internal pressure are determined by detailed Finite Element Analysis (FEA) and compared to values determined using NUREG/CR-6007 equations. The containment vessel is of small diameter with an inwardly dished bolted head that geometrically contrasts with the large, flat lidded casks which the NUREG addressed. The comparison showed a significant difference in the magnitude of pressure driven prying load between the FEA model and the NUREG approximate equations. This difference affected the predicted pressure that overcomes preload, and the rate of load increase after preload was exceeded. The difference was likely due to the contrasts between this vessel’s closure shape compared to the more typical flat cask lid shape used in the NUREG development.

Global model generation for a capacitive silicon accelerometer by finite-element analysis

1998 ◽  
Vol 67 (1-3) ◽  
pp. 153-158 ◽  
Author(s):  
Y. Ansel ◽  
B. Romanowicz ◽  
P. Renaud ◽  
G. Schröpfer
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Global Model ◽  
Model Generation ◽  
Element Analysis

scholarly journals Effects of Flotage on Immersion Indentation Results of Bone Tissue: An Investigation by Finite Element Analysis

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Mingxing Zhou ◽  
Zunqiang Fan ◽  
Zhichao Ma ◽  
Yue Guo ◽  
Liguo Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Nanoindentation Test ◽  
Liquid Media ◽  
Depth Sensing ◽  
Element Analysis ◽  
Fea Simulation ◽  
The Difference

In reality, nanoindentation test is an efficient technique for probing the mechanical properties of biological tissue that soaked in the liquid media to keep the bioactivity. However, the effects of flotage imposed on the indenter will lead to inaccuracy when calculating mechanical properties (for instance, elastic modulus and hardness) by using depth-sensing nanoindentation. In this paper, the effects of flotage on the nanoindentation results of cortical bone were investigated by finite element analysis (FEA) simulation. Comparisons of nanoindentation simulation results of bone samples with and without being soaked in the liquid media were carried out. Conclusions show that the difference of load-displacement curves in the case of soaking sample and without soaking sample conditions varies widely based on the change of indentation depth. In other words, the nanoindentation measurements in liquid media will cause significant error in the calculated Young’s modules and hardness due to the flotage. By taking into account the effect of flotage, these errors are particularly important to the accurate biomechanics characterization of biological samples.

Effects of Positions of Thermistors on the Airflow Accelarater Output by 3D Finite Element Analysis

2010 ◽  
Vol 20-23 ◽  
pp. 1434-1438
Author(s):  
Yan Jie Li ◽  
Lin Hua Piao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Temperature Field ◽  
Three Dimensional ◽  
Sense Organ ◽  
Measurement Range ◽  
Three Dimensional Model ◽  
Temperature Field Distribution ◽  
Element Analysis ◽  
The Difference

With the method of FEA (finite element analysis), the distribution of temperature field in sense organ at different arrangements of hot-resistances and different accelerations, were obtained by building the three-dimensional model of airflow acceleration sensor’s sense organ.The results are asfollows: When the acceleration is not same, the temperature field distribution near the wires is different; The difference of temperature of 2 symmetry detection thermistors ΔT has also changed. If not beyond the measurement range, The more close to the heat flow center,the greater temperature difference between the two hot-resistances,and the greater output of voltage.

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