scholarly journals Research of Fracture Mechanics Applied in the Cutting Process of Plastic Metals

2019 ◽  
Vol 37 (6) ◽  
pp. 1209-1222
Author(s):  
Hongyan Shi ◽  
Xianfeng Zhao ◽  
Ziqin Wang ◽  
Xueting Jiang ◽  
Zichuan Zou ◽  
...  
Keyword(s):  
Fracture Mechanics ◽  
Early Development ◽  
Cutting Process ◽  
Cutting Mechanism ◽  
Current Application ◽  
Shear Theory ◽  
Key Points ◽  
Development Direction ◽  
Fracture Theory ◽  
Physical Phenomena

Shear theory is the mainstream view to explain the cutting process. Because of the complexity of the cutting process, it is still difficult to explain and predict the physical phenomena in the cutting process accurately by shear theory. While some physical phenomena can be well explained by fracture theory. At the same time, with the development of fracture theory, fracture phenomenon in cutting process has attracted scholarsattention again. Therefore, the early development and current application of fracture theory in the study of cutting process are reviewed in detail. The research results and key points of fracture theory in cutting process are summarized. The development direction of fracture theory in the cutting process is briefly discussed. It is considered that the integration of fracture theory and shear theory is an effective way to study cutting mechanism, and the cutting process is divided into six stages in order to integrate fracture and shear theory.

scholarly journals Genome-wide analysis shows that Ldb1 controls essential hematopoietic genes/pathways in mouse early development and reveals novel players in hematopoiesis

Blood ◽  
2013 ◽  
Vol 121 (15) ◽  
pp. 2902-2913 ◽  
Author(s):  
Athina Mylona ◽  
Charlotte Andrieu-Soler ◽  
Supat Thongjuea ◽  
Andrea Martella ◽  
Eric Soler ◽  
...  
Keyword(s):  
Early Development ◽  
Yolk Sac ◽  
Genome Wide Analysis ◽  
Genome Wide ◽  
Key Points ◽  
Differentiation Block ◽  
Early Developmental

Key Points Lack of yolk-sac hematopoiesis in the Ldb1−/− mouse results from a decreased number of hemangioblasts and a differentiation block. Identification of genes and pathways regulated by Ldb1 in the hemangioblast reveals potential targets for early developmental manipulation.

Advances in Three-Dimensional Fracture Mechanics

2006 ◽  
Vol 312 ◽  
pp. 27-34 ◽  
Author(s):  
Wan Lin Guo ◽  
Chongmin She ◽  
Jun Hua Zhao ◽  
Bin Zhang
Keyword(s):  
Fracture Mechanics ◽  
Deformation Theory ◽  
Three Dimensional ◽  
Unified Theory ◽  
Constraint Factor ◽  
Engineering Structures ◽  
The Past ◽  
Fatigue And Fracture ◽  
Fracture Theory ◽  
Historical Developments

The historical developments of the fracture mechanics from planar theory to threedimensional (3D) theory are reviewed. The two-dimensional (2D) theories of fracture mechanics have been developed perfectly in the past 80 years, and are suitable for some specific cases of engineering applications. However, in the complicated 3D world, the limitation of the 2D fracture theory has become evident with development of the structure toward complication and micromation. In the 1990’s, Guo has proposed the 3D fracture theory with a 3D constraint factor based on the deformation theory and energy theory. The proposed 3D theory can predict accurately the fracture problems for practical and complicated engineering structures with defects, by integrating the 3D theory of fatigue, which has been developed to unify fatigue and fracture. Our efforts to develop the 3D fracture mechanics and the unified theory of 3D fatigue and fracture are summarized, and perspectives for future efforts are outlined.

The Nano-Cutting Mechanism Research of Polysilicon Based on Molecular Dynamics

2013 ◽  
Vol 690-693 ◽  
pp. 2559-2562
Author(s):  
Ying Zhu ◽  
Shun He Qi ◽  
Zhi Xiang ◽  
Ling Ling Xie
Keyword(s):  
Molecular Dynamics ◽  
Potential Energy ◽  
Cutting Force ◽  
Cutting Process ◽  
Dynamics Simulation ◽  
Cutting Mechanism ◽  
Nanometric Cutting ◽  
Mechanism Research ◽  
Atom Position ◽  
Dynamics Method

Molecular dynamics model of the polysilicon material under the micro/nanoscale is established by using molecular dynamics method, make variety of the typical defects distribute to the polysilicon model reasonable and relax the simulation model, obtain the system potential energy curves in the relaxation process and the atomic location figure after the relaxation. Conduct molecular dynamics simulation of nanometric cutting process relying on the development of simulation program, get instant atom position image and draw the cutting force curve. Discusses the typical defects impact on the polycrystalline silicon nanometric cutting process, those mainly include cutting force changes in the cutting process, potential energy changes and processed surface quality etc.

A Brief Analysis of the Application of Green Textiles in Children’s Space Environment Design

2014 ◽  
Vol 1048 ◽  
pp. 354-357
Author(s):  
Xuan Li
Keyword(s):  
Status Quo ◽  
Space Environment ◽  
Environment Design ◽  
Current Application ◽  
Application Range ◽  
Development Status ◽  
Security Issues ◽  
Development Direction ◽  
The Status ◽  
Ecological Standard

This article starts from discussing the quality and security issues of children’s textiles inrecent years, then it analyzes the current application range of children’s textiles in their space environment, the development status of children’s green textiles and the application of children’s space environment. From the status quo and the perspective of domestic and abroad ecological standard of green textiles, the article emphasizes on the importance of green textiles application in children’s space environment designs. It also points out that green textiles will become the development direction of children’s textiles. Finally, it offers according strategies and suggestions.

scholarly journals Advances in remediation of heavy metal contaminated soil and water by Leersia hexandra Swartz

2020 ◽  
Vol 194 ◽  
pp. 04035
Author(s):  
Hui Qin ◽  
Hua Lin
Keyword(s):  
Heavy Metal ◽  
Environmentally Friendly ◽  
Treatment Method ◽  
Polluted Water ◽  
Human Beings ◽  
Current Application ◽  
Development Direction ◽  
Leersia Hexandra ◽  
Leersia Hexandra Swartz ◽  
Enrichment Characteristics

Heavy metal pollution is extremely harmful to human beings. Looking for an efficient and environmentally friendly treatment method is the focus of current research. Using plants to treat contaminated water and soil has proven to be an effective and environmentally friendly method. Leersia hexandra Swartz is a chromium hyperaccumulator, and it can also enrich copper and nickel. Since the super enrichment characteristics of Leersia hexandra Swartz were discovered, many scholars have poured into the research on Leersia hexandra Swartz. This article will give an overview of the current application status of Leersia hexandra Swartz’s purification of polluted water and soil, analyze the methods and principles used, and discuss the future development direction of Leersia hexandra Swartz’s plant remediation technology.

Design of bamboo cutting mechanism based on crack propagation principle

BioResources ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. 5890-5900
Author(s):  
Yunyi Guan ◽  
Shouzhong Li ◽  
Xiong Jiang ◽  
Binhao Xu ◽  
Pingyi Liu ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Cutting Process ◽  
Solid Model ◽  
Work Efficiency ◽  
Cutting Mechanism ◽  
Movement Process ◽  
Cutting Operation ◽  
Basic Movement

Bamboo is mainly grown in hilly areas, and the harvesting of bamboo basically relies on labor. Moreover, the bamboo is prone to splitting problems during harvesting. To liberate labor and improve work efficiency, the crack propagation principle of bamboo was studied. Based on this study, a new cutting scheme using spiral feed was proposed. Additionally, a new bamboo cutting mechanism was designed. The new cutting mechanism, when installed on a harvesting vehicle, can automatically complete the cutting operation. The cutting mechanism is different from the traditional ones, and it uses four sets of saw blades for spiral feed cutting around the bamboo, which can reduce the splitting probability during the cutting process. Finally, a solid model of the cutting mechanism was built, and the basic movement process was simulated to verify the feasibility of the bamboo cutting mechanism.

A General Mathematical Model for Gears Cut by CNC Hobbing Machines

1997 ◽  
Vol 119 (1) ◽  
pp. 108-113 ◽  
Author(s):  
Shinn-Liang Chang ◽  
Chung-Biau Tsay ◽  
Shigeyoshi Nagata
Keyword(s):  
Mathematical Model ◽  
Degree Of Freedom ◽  
Cutting Process ◽  
Generation Process ◽  
Cutting Mechanism ◽  
Gear Cutting ◽  
Different Types ◽  
General Mathematical Model ◽  
Crossed Axes ◽  
The Mathematical Model

A hobbing machine’s cutting mechanism is a mechanism with multi-degree of freedom during the cutting process. In this paper, we propose a general gear mathematical model simulating the generation process of a 6-axis CNC hobbing machine based on the cutting mechanism of CNC hobbing machine and worm-type hob cutter. The proposed gear mathematical model can be applied to simulate different types of gear cutting. Some examples are included to verify the mathematical model. Also, a novel type of gear named “Helipoid” which can be used in crossed axes transmission is proposed. The proposed general gear mathematical model can facilitate a more thorough understanding of generation processes and toward the development of novel types of gears.

scholarly journals Real-Manufacturing-Process Finite Element Modeling of Aramid Honeycomb for Cutting Mechanism Revealing

2021 ◽  
Author(s):  
Yuxing Yang ◽  
Yongjie Bao ◽  
Qihao Xu ◽  
Jinlong Wang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Manufacturing Process ◽  
Element Model ◽  
Cutting Process ◽  
Disc Cutter ◽  
Cutting Mechanism ◽  
Initial State ◽  
Final State ◽  
Cutting Experiment

Abstract A finite element model for honeycomb cutting was proposed to reveal its cutting mechanism in the process of cutting with disc cutter, which solves the problem of efficient honeycomb cutting modeling by imitating the real manufacturing process of the aramid honeycomb and solves the problem of honeycomb material assignment by developing a material calculation method. Cutting experiment of ACCH-1-1.83-48 aramid honeycomb specimen concerning on the cutting forces response and cutting damages was conducted. The comparison between the finite element model results and the experimental results validated that the proposed method was effective for investigating the cutting process and mechanism for the aramid honeycomb. Predicted cutting mechanism results show that: (a) cutting process of the aramid honeycomb can be divided into 3 stages with 4 characteristic states: initial state, cut-in state, cut-out state and final state; (b) cell wall bending in the cutting direction relieves the cutting force, and strong plasticity of the aramid fiber makes it hard to break, which lead to uncut fiber and burr damages; (c) using sharp tip cutter as well as bonding both top and bottom of the honeycomb to two stiffer parts individually are beneficial to obtain good cutting quality with less damages.

On Fractal Cracks in Micropolar Elastic Solids

2001 ◽  
Vol 69 (1) ◽  
pp. 45-54 ◽  
Author(s):  
A. Yavari ◽  
S. Sarkani ◽  
E. T. Moyer,
Keyword(s):  
Fracture Mechanics ◽  
Dimensional Analysis ◽  
Asymptotic Method ◽  
Couple Stress ◽  
Stress Singularity ◽  
Stress Singularities ◽  
Elastic Solids ◽  
Fracture Theory ◽  
Fractal Crack ◽  
Fractal Cracks

In this paper we review the fracture mechanics of smooth cracks in micropolar (Cosserat) elastic solids. Griffith’s fracture theory is generalized for cracks in micropolar solids and shown to have two possible forms. The effect of fractality of fracture surfaces on the powers of stress and couple-stress singularity is studied. We obtain the orders of stress and couple-stress singularities at the tip of a fractal crack in a micropolar solid using dimensional analysis and an asymptotic method that we call “method of crack-effect zone.” It is shown that orders of stress and couple-stress singularities are equal to the order of stress singularity at the tip of the same fractal crack in a classical solid.

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