scholarly journals Sampling and Distribution Parameter Analysis for Estimating Three-dimensional Fracture Orientation Distributions from a Circular Sampling Window

2021 ◽  
Vol 861 (2) ◽  
pp. 022003
Author(s):  
Xiaojun Wang ◽  
Qi Zhang ◽  
Hehua Zhu
Keyword(s):  
Three Dimensional ◽  
Distribution Parameter ◽  
Parameter Analysis ◽  
Fracture Orientation ◽  
Sampling Window ◽  
Orientation Distributions

Metal Forming With Laser Origami: Parameter Analysis and Optimization

2020 ◽  
Author(s):  
Peiwen J. Ma ◽  
Yue Hao ◽  
Jyh-Ming Lien ◽  
Edwin A. Peraza Hernandez
Keyword(s):  
Metal Forming ◽  
Search Algorithm ◽  
Minimum Energy ◽  
Three Dimensional ◽  
Parameter Analysis ◽  
Forming Process ◽  
Polygonal Mesh ◽  
Target Shape ◽  
Material Usage ◽  
Metal Forming Process

Abstract Laser origami is a metal forming process where an initially planar sheet is transformed into a target three-dimensional (3D) form through cutting and folding operations executed by a laser beam. A key challenge in laser origami is to determine the locations of the cuts and folds required to transform the planar sheet into the 3D target shape. The region of the planar sheet that can be transformed into the target shape through these cuts and folds is denoted as the net. This paper presents a method to determine optimal net(s) for laser origami based on criteria including minimum energy usage, minimum fabrication time, minimum error in the fold angles, and minimum material usage. The 3D target shape is given as a polygonal mesh. To generate a net, each edge in the mesh must be classified as a cut or a fold. The energy, time, and other parameters associated with cutting or folding each edge are determined using experimentally calibrated formulas. A search algorithm is subsequently implemented to find combinations of cut and folded edges that provide an optimal set of nets for the given 3D target shape based on a cost function. Nets that are disconnected or have overlapping regions are discarded since they are invalid for laser origami. The method is demonstrated by applying it to different target shapes and cost functions.

A New Method for Three-Dimensional Fracture Network Modelling for Trace Data Collected in a Large Sampling Window

2019 ◽  
Vol 53 (3) ◽  
pp. 1145-1161 ◽  
Author(s):  
Zhenbang Nie ◽  
Jianping Chen ◽  
Wen Zhang ◽  
Chun Tan ◽  
Zhifa Ma ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Fracture Network ◽  
New Method ◽  
Network Modelling ◽  
Trace Data ◽  
Sampling Window

Coupling fractal model for fretting wear on rough contact surfaces

2020 ◽  
pp. 1-32
Author(s):  
Yi Wang ◽  
Gang Liang ◽  
Shuo LIU ◽  
Yi Cui
Keyword(s):  
Contact Surface ◽  
Fractal Theory ◽  
Three Dimensional ◽  
Parameter Analysis ◽  
Fretting Wear ◽  
Wear Depth ◽  
Contact Parameter ◽  
Wear Process ◽  
Actual Surface ◽  
Fractal Parameters

Abstract In this paper, a fretting damage model based on fractal theory is proposed. The Weierstrass-Mandelbrot function of fractal theory is used to represent the rough contact surface, and a corresponding contact parameter analysis method is also established. Based on neural network algorithm, the values of fractal parameters are fitted, and the fitting accuracy has been greatly improved compared with traditional methods. According to the fractal parameters of the actual surface, the fretting wear process of the rough contact surface is analyzed based on theory of adhesive and three body abrasive wear. A generic program for the analysis of three-dimensional fretting wear problems is also proposed. Compared with material tests, the prediction error of fretting wear simulation model is 13.4% for wear depth and 16.7% and 3.9% for width and length of wear scar in stable wear stage. The prediction results show that the model can be applied to the prediction of the actual three-dimensional fretting wear model.

Numerical Investigation on the Fracture Behaviors of Three-Dimensional Functionally Graded Materials

2007 ◽  
Vol 353-358 ◽  
pp. 1098-1101 ◽  
Author(s):  
Hong Jun Yu ◽  
Li Cheng Guo ◽  
Lin Zhi Wu
Keyword(s):  
Functionally Graded Materials ◽  
Crack Front ◽  
Material Properties ◽  
High Efficiency ◽  
Three Dimensional ◽  
Functionally Graded ◽  
Parameter Analysis ◽  
Graded Materials ◽  
Gaussian Integration ◽  
Fracture Behaviors

Functionally graded materials (FGMs) with continuous varying properties have absorbed great attention for the purpose of eliminating the mismatch of material properties which may result in cracking. In this paper, three-dimensional finite element method (3D FEM) based on nonhomogeneous elements is used to study the fracture behaviors of a 3D FGM plate. Since real material properties at Gaussian integration points are adopted during forming the element stiffness matrix, the nonhomogeneous material properties can be applied in each element. Moreover, 20-node singular elements are used around the crack front to deal with the singularity of stress fields at the crack front. By this way, the stress intensity factors (SIFs) can be calculated with high efficiency and accuracy. Therefore, compared with the general FEM using homogeneouos elements, the calculating efficiency and accuracy can be increased. Finally, parameter analysis is conducted. It is found that the material nonhomogeneity constant and the crack parameter have significant influences on the SIFs.

Estimation of fiber orientation and length distribution in cashmere fibrous assemblies

2018 ◽  
Vol 89 (6) ◽  
pp. 1084-1093
Author(s):  
Hui Jing ◽  
WeiDong Yu
Keyword(s):  
Fiber Orientation ◽  
Fiber Length ◽  
Three Dimensional ◽  
Length Distribution ◽  
3D Data ◽  
Orientation Fields ◽  
Orientation Distributions ◽  
Micro Tomography ◽  
Fibrous Assemblies ◽  
First Time

In a general fibrous assembly, single fiber orientation as well as fiber length distributions are important characteristics because they directly influence the properties of textiles. An X-ray micro-tomography experiment with a high resolution of 3 μm was for the first time conducted on a randomly oriented inner Mongolia cashmere fibrous assembly to get a series of two-dimensional projections from different angles and the corresponding cone–beam algorithm proposed by Feldkamp and volume rendering technique were used to realize the three-dimensional (3D) reconstruction. An automated segmentation algorithm described by Rigort and Weber was used to trace and detect single fibers from tomographic 3D data. Local normalized cross-correlation of the tomograms was computed with a cylindrical template that mimics a short microtubule segment to get two new objects, named the correlation and orientation fields. Tracing results of fiber length and orientation distributions were given in this paper statistically.

In Situ Observation of Recovery and Grain Growth in High Purity Aluminum

2012 ◽  
Vol 715-716 ◽  
pp. 447-454 ◽  
Author(s):  
C. M. Hefferan ◽  
S. F. Li ◽  
J. Lind ◽  
Ulrich Lienert ◽  
Anthony D. Rollett ◽  
...  
Keyword(s):  
High Purity ◽  
Three Dimensional ◽  
High Energy ◽  
X Ray Diffraction ◽  
Grain Structures ◽  
Modeling Analysis ◽  
Orientation Distributions ◽  
High Purity Aluminum ◽  
Diffraction Microscopy

We have used high energy x-ray diffraction microscopy (HEDM) to study annealing behavior in high purity aluminum. In-situ measurements were carried out at Sector 1 of the Advanced Photon Source. The microstructure in a small sub-volume of a 1 mm diameter wire was mapped in the as-received state and after two differential anneals. Forward modeling analysis reveals three dimensional grain structures and internal orientation distributions inside grains. The analysis demonstrates increased ordering with annealing as well as persistent low angle internal boundaries. Grains that grow from disordered regions are resolution limited single crystals. Together with this recovery behavior, we observe subtle motions of some grain boundaries due to annealing.

scholarly journals Three-dimensional cellular automata modelling of cleavage propagation across crystal boundaries in polycrystalline microstructures

2015 ◽  
Vol 471 (2177) ◽  
pp. 20150039 ◽  
Author(s):  
A. Shterenlikht ◽  
L. Margetts
Keyword(s):  
Cellular Automata ◽  
Grain Boundaries ◽  
Three Dimensional ◽  
Element Model ◽  
Length Scale ◽  
Orientation Tensor ◽  
Multi Scale ◽  
Ca Model ◽  
Orientation Distributions ◽  
Crystal Boundaries

A three-dimensional cellular automata (CA) with rectilinear layout is used in this work to create and cleave polycrystalline microstructures. Each crystal is defined by a unique randomly generated orientation tensor. Separate states for grains, grain boundaries, crack flanks and crack fronts are created. Algorithms for progressive cleavage propagation through crystals and across grain boundaries are detailed. The mesh independent cleavage criterion includes the critical cleavage stress and the length scale. Resolution of an arbitrary crystallographic plane within a 26-cell Moore neighbourhood is considered. The model is implemented in Fortran 2008 coarrays. The model gives realistic predictions of grain size and mis-orientation distributions, grain boundary topology and crack geometry. Finally, we show how the proposed CA model can be linked to a finite-element model to produce a multi-scale fracture framework.

Sign in / Sign up

Export Citation Format

Share Document