scholarly journals Fundamentals of cutting

2016 ◽  
Vol 6 (3) ◽  
pp. 20150108 ◽  
Author(s):  
J. G. Williams ◽  
Y. Patel
Keyword(s):  
Fracture Toughness ◽  
Elastic Modulus ◽  
Fracture Mechanics ◽  
Yield Stress ◽  
Material Properties ◽  
Orthogonal Cutting ◽  
Wedge Angle ◽  
Tool Geometry ◽  
Plastic Shear ◽  
Plastic Bending

The process of cutting is analysed in fracture mechanics terms with a view to quantifying the various parameters involved. The model used is that of orthogonal cutting with a wedge removing a layer of material or chip. The behaviour of the chip is governed by its thickness and for large radii of curvature the chip is elastic and smooth cutting occurs. For smaller thicknesses, there is a transition, first to plastic bending and then to plastic shear for small thicknesses and smooth chips are formed. The governing parameters are tool geometry, which is principally the wedge angle, and the material properties of elastic modulus, yield stress and fracture toughness. Friction can also be important. It is demonstrated that the cutting process may be quantified via these parameters, which could be useful in the study of cutting in biology.

Assessment of Mechanical Properties of Cold Formed Steel Material at Elevated Temperature

2016 ◽  
Vol 846 ◽  
pp. 27-36
Author(s):  
Fadhluhartini Muftah ◽  
Mohd Syahrul Hisyam Mohd Sani ◽  
Ahmad Rasidi Osman ◽  
Mohd Azran Razlan ◽  
Shahrin Mohammad
Keyword(s):  
Elastic Modulus ◽  
Elevated Temperature ◽  
Ambient Temperature ◽  
Yield Stress ◽  
Material Properties ◽  
High Efficiency ◽  
Strain Curve ◽  
Ultimate Stress ◽  
Fire Incident ◽  
Cold Formed Steel

Fire accident is considered as the one of most severe environmental hazards to building and infrastructure. Cold formed steel (CFS) beam has been used extensively as primary load bearing structural member in many applications in the building construction due to high efficiency in term of production, fabrication, and assembling in construction. This material must be well perform in fire incident in term of its integrity and stability of structural for a period of time. Hence, the assessment of the material properties of this material is greatly important in order to predict the performance of this structure under fire incident. The tensile coupon tests of CFS are according to BS EN 10002-1:2001. The CFS material G450 with 1.9 mm thickness is used in this study. The elastic modulus, yield stress, correspondent percentage strain at yield stress, ultimate stress, and correspondent percentage strain of ultimate stress was 200.3 GPa, 540.5 MPa, 0.478 %, 618.8 MPa, and 8.701 % respectively. The results of the ambient temperature test have been used to assess the mechanical strength of CFS at elevated temperature. The discussion of material properties is based on EC3-1-2 and proposed model from other researchers. The main material properties discussed is the stress-strain curve, elastic modulus, yield strength at elevated temperature was determined. The actual elastic region is slightly lower than the prediction of EC3-1.2 at ambient temperature, but well fit with two other studies. Besides that, the actual material properties experience strain hardening after yielding and reach a maximum stress up to 618 MPa while EC3-1.2 predict the constant value of the yield stress after yield until 15 % strain,other two study was fit the ambient tensile test up to ultimate stress, and fit until 2 % strain level.

Development of a Novel Test Method to Characterize Material Properties in Corrosive Environments for Subsea HPHT Design

2019 ◽  
Vol 142 (3) ◽  
Author(s):  
Ramgopal Thodla ◽  
Colum Holtam ◽  
Rajil Saraswat
Keyword(s):  
Fracture Toughness ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Intensity Factor ◽  
Crack Growth ◽  
Cathodic Protection ◽  
Material Properties ◽  
Test Method ◽  
Corrosive Environments

Abstract High pressure high temperature (HPHT) design is a significant new challenge facing the subsea sector, particularly in the Gulf of Mexico. API 17TR8 provides HPHT Design Guidelines, specifically for subsea applications. Fatigue endurance (i.e., S–N) and fracture mechanics design are both permitted, depending on the criticality of the component. Both design approaches require material properties generated in corrosive environments, such as seawater with cathodic protection and/or sour production fluids. In particular, it is necessary to understand sensitivity to cyclic loading frequency (for both design approaches), crack growth rates (CGR) (for fracture mechanics approach) as well as fracture toughness performance. For many subsea components, the primary source of fatigue loading is associated with the start-up and subsequent shutdown operation of the well, with long hold periods in-between, during which static crack growth (CG) could occur. These are the two damage modes of most interest when performing a fracture mechanics based analysis. This paper presents the preliminary results of a novel single specimen test method that was developed to provide fatigue crack growth rate (FCGR) and fracture toughness data in corrosive environments, in a timeframe that is compatible with subsea HPHT development projects. Test data generated on alloy 625+ in seawater with cathodic protection are presented along with a description of how the test method was developed. A crack tip strain rate based formulation was applied to the data to rationalize the effect of frequency, stress intensity factor range (ΔK), and maximum stress intensity factor (Kmax).

Development of a Novel Test Method to Characterize Material Properties in Corrosive Environments for Subsea HPHT Design

2017 ◽  
Author(s):  
Ramgopal Thodla ◽  
Colum Holtam ◽  
Rajil Saraswat
Keyword(s):  
Fracture Toughness ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Intensity Factor ◽  
Crack Growth ◽  
Cathodic Protection ◽  
Material Properties ◽  
Test Method ◽  
Corrosive Environments

High pressure high temperature (HPHT) design is a significant new challenge facing the subsea sector, particularly in the Gulf of Mexico. API 17TR8 provides HPHT Design Guidelines, specifically for subsea applications. Fatigue endurance (i.e. S-N) and fracture mechanics design are both permitted, depending on the criticality of the component. Both design approaches require material properties generated in corrosive environments, such as seawater with cathodic protection and/or sour production fluids. In particular, it is necessary to understand sensitivity to cyclic loading frequency (for both design approaches), crack growth rates (for fracture mechanics approach) as well as fracture toughness performance. For many subsea components, the primary source of fatigue loading is associated with the start-up and subsequent shutdown operation of the well, with long hold periods in-between, during which static crack growth could occur. These are the two damage modes of most interest when performing a fracture mechanics based analysis. This paper presents the preliminary results of a novel single specimen test method that was developed to provide fatigue crack growth rate and fracture toughness data in corrosive environments, in a timeframe that is compatible with subsea HPHT development projects. Test data generated on alloy 625+ in seawater with cathodic protection is presented along with a description of how the test method was developed. A crack tip strain rate based formulation was applied to the data to rationalize the effect of frequency, stress intensity factor range (ΔK) and maximum stress intensity factor (Kmax).

Yielding and Fracture Toughness of Glass Microballoon-Filled Epoxy Composites

2001 ◽  
Vol 9 (5) ◽  
pp. 345-350 ◽  
Author(s):  
A.M. Zihlif ◽  
G. Ragosta
Keyword(s):  
Fracture Toughness ◽  
Elastic Modulus ◽  
Strain Rate ◽  
Yield Stress ◽  
Thermal Behaviour ◽  
Filler Content ◽  
Fracture Behaviour ◽  
Rate Dependence ◽  
Epoxy Composites ◽  
Yielding Process

The yielding and fracture behaviour of epoxy/glass microballoon composites has been studied as a function of filler content, temperature and strain rate. No increase in elastic modulus, yield stress and fracture toughness was observed. The compressive yield stress of the composites showed strain rate dependence with more than one rate-activated yielding process. The fracture toughness parameters Gc and Kc were found to be temperature insensitive. The variations in the measured mechanical quantities are discussed in terms of the observed morphology and thermal behaviour of the epoxy composites.

Experimental Investigations of the Effects of Multiple Heat Straightening Repair on the Structural Properties of Bridge Steels

2005 ◽  
Vol 1907 (1) ◽  
pp. 67-77
Author(s):  
Keith Kowalkowski ◽  
Amit H. Varma
Keyword(s):  
Fracture Toughness ◽  
Elastic Modulus ◽  
Yield Stress ◽  
Structural Properties ◽  
Surface Hardness ◽  
Ultimate Stress ◽  
Experimental Investigations ◽  
Percent Elongation ◽  
Damage Repair ◽  
Heat Straightening

The effects of multiple damage-heat straightening repair cycles (i.e., multiple cycles of damage followed by heat straightening repair) on the fundamental structural properties of typical bridge steels ASTM A36, A588, and A7 were evaluated. The damage and repair parameters considered in the study are the damage strain (ed), the restraining stress (sr), and the number of multiple damage-repair cycles (Nr). The effects of these parameters on the following structural properties were evaluated: elastic modulus, yield stress, ultimate stress, percent elongation, surface hardness, and fracture toughness. Seventy-five laboratory-scale specimens made from A36, A588, or A7 steel were subjected to multiple damage-repair cycles, and their effects on the structural properties were evaluated. The results indicate that multiple damage-repair cycles have a small influence (±15%) on the elastic modulus, yield stress, and ultimate stress. However, the percent elongation and fracture toughness of the damaged-repaired steel are influenced significantly. On the basis of reductions in the percent elongation and fracture toughness, it is recommended that A7 and A36 steel be limited to three damage-heat straightening repair cycles. A588 steel can be subjected to five damage-heat straightening repair cycles.

An elastic-plastic indentation model and its solutions

1996 ◽  
Vol 11 (9) ◽  
pp. 2358-2367 ◽  
Author(s):  
Weiping Yu ◽  
James P. Blanchard
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Elastic Modulus ◽  
Yield Stress ◽  
Material Properties ◽  
Hardness Test ◽  
Plastic Materials ◽  
Indentation Tests ◽  
Plastic Indentation ◽  
Comparison With Experimental Data

An analytical model of hardness has been developed. Four major indentation tests, namely indentation by cones, wedges, spheres, and flat-ended, axisymmetric cylinders have been analyzed based on the model. Analytical relationships among hardness, yield stress, elastic modulus, Poisson's ratio, and indenter geometries have been found. These results enable hardness to be calculated in terms of uniaxial material properties and indenter geometries for a wide variety of elastic and plastic materials. These relationships can also be used for evaluating other mechanical properties through hardness measurements and for converting hardness from one type of hardness test into those of a different test. Comparison with experimental data and numerical calculations is excellent.

A novel model of Z-pin insertion in prepreg based on fracture mechanics

2021 ◽  
pp. 095440542110144
Author(s):  
Guobiao Ji ◽  
Liang Cheng ◽  
Shaohua Fei ◽  
Jiangxiong Li ◽  
Yinglin Ke
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Analytical Model ◽  
Model Parameters ◽  
Force Model ◽  
Fe Model ◽  
Cohesive Elements ◽  
Fe Method ◽  
Insertion Force ◽  
Mechanics Model

Through-thickness reinforcement is a promising solution to the problem of delamination susceptibility in laminated composites. Modeling Z-pin–prepreg interaction is essential for accurate robotics-assisted Z-pin insertion. In this paper, a novel Z-pin insertion force model combining the classical cohesive finite element (FE) method with a dynamic analytical fracture mechanics model is proposed. The velocity-dependent cohesive elements, in which the fracture toughness is provided by the analytical model, are implemented in Z-pin insertion FE model to predict the crack initiation and propagation. Then Z-pin insertion experiments are performed on prepreg sample with metallic Z-pins at different velocities to identify the analytical model parameters and validate the simulation predictions offered by the model. Dynamics of Z-pin interaction with inhomogeneous prepreg is described and the effects of insertion velocity on prepreg contact force are studied. Results show that the force model agrees well with experiments and the fracture toughness rises with the increasing Z-pin insertion velocity.

scholarly journals Shear modulus and yield stress of foams: contribution of interfacial elasticity

Soft Matter ◽  
2021 ◽  
Vol 17 (14) ◽  
pp. 3937-3944
Author(s):  
Annika R. Völp ◽  
Norbert Willenbacher
Keyword(s):  
Elastic Modulus ◽  
Block Copolymer ◽  
Shear Modulus ◽  
Yield Stress ◽  
Protein Food ◽  
General Correlation

A general correlation of foam shear modulus G0 and yield stress τy with the interfacial elastic modulus of foaming solutions in shear and dilation E∞ was found for surfactant, block-copolymer, protein, food, and particle-stabilized foams.

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