Life and Wear Prediction of Twist Drills by a Temperature Dependent Friction Law

2010 ◽  
Author(s):  
Hossein Vaghefpour ◽  
Ali Nayebi
Keyword(s):  
Material Flow ◽  
Mechanical Model ◽  
Cutting Speed ◽  
Contact Length ◽  
Temperature Dependent ◽  
Friction Law ◽  
Proposed Model ◽  
Tangential Forces ◽  
Twist Drills ◽  
Good Agreement

This paper describes the material flow in shear zone by using a thermo mechanical model. The material is an isotropic, viscoplastic rigid material; its behavior is described by a J–C law. The contact length between the chip and the tool and the temperature distribution at the tool–chip interface which has an important effect on the tool wear. Using the thermo-mechanical model and the temperature friction law, the tangential forces, friction coefficient and contact length on the cutting element as a function of radius, for different feed rate and cutting speed, are obtained. The results of proposed model are compared with experimental results and good agreement is obtained.

Effect of Cutting Parameters on Tool Life: Case Study Twist Drill

2015 ◽  
Vol 1101 ◽  
pp. 397-401
Author(s):  
Hossein Vaghefpour ◽  
Ali Dahar ◽  
Kobra Zabeh
Keyword(s):  
Temperature Distribution ◽  
Cutting Forces ◽  
Flow Direction ◽  
Orthogonal Cutting ◽  
Viscoelastic Model ◽  
Cutting Speed ◽  
Contact Length ◽  
Friction Law ◽  
Chip Flow ◽  
Twist Drills

<p>This study discusses the relationship between various parameters of drilling and cutting tools using an analytical model is developed for predicting life and wear of twist drills by a temperature dependent friction law. The model permits the continuous determination of the cutting forces along the cutting lips and chisel edge which can be combined with the dynamics forces of the initial penetration and the chip evacuation forces in drilling .The approach is based on representing the cutting forces along the cutting lips as a series of oblique elements. Similarly, cutting in the chisel region is treated as orthogonal cutting with different speeds depending on the radial location. The chip flow is determined by the assumption that the friction force on the tool face is collinear to the chip flow direction. The contact length between the chip and the tool and the temperature distribution at the tool–chip interface which has an important effect on the tool wear were predicted. The model permits to predict the chip flow direction, the contact length between the chip and the tool and the temperature distribution at the tool–chip interface. Using the thermo-viscoelastic model and the temperature friction law, the tangential forces, friction coefficient and contact length on the cutting element as a function of radius, for different feed rate and cutting speed, are obtained. The proposed model results are compared with experimental results and good agreement is obtained.</p>

Modeling of twist drills wear by a temperature-dependent friction law

2008 ◽  
Vol 207 (1-3) ◽  
pp. 98-106 ◽  
Author(s):  
A. Nayebi ◽  
G. Mauvoisin ◽  
H. Vaghefpour
Keyword(s):  
Temperature Dependent ◽  
Friction Law ◽  
Twist Drills

Micro-Mechanical Modeling of the Stress Softening in Double-Network Hydrogels

2018 ◽  
Author(s):  
Vahid Morovati ◽  
Roozbeh Dargazany
Keyword(s):  
Mechanical Model ◽  
Large Deformations ◽  
Axial Loading ◽  
Mechanical Modeling ◽  
Micro Structure ◽  
Double Network ◽  
Proposed Model ◽  
Loading And Unloading ◽  
Inelastic Phenomenon ◽  
Good Agreement

While single network hydrogels show limited extensibility and low strength, double-network hydrogels benefit from significantly high stretchability and toughness due to their reinforcing mechanism of combining two soft and rigid networks. Here, a micro-mechanical model is developed to characterize the constitutive behavior of DN hydrogels in quasi-static large deformation. In particular, we focused on describing the permanent damage in DN gels under large deformations. Irreversible chain detachment and decomposition of the first network are explored as the underlying reasons for the nonlinear inelastic phenomenon. The proposed model enables us to describe the damage and the way it influences the micro-structure of the gel. The model is validated with uni-axial loading and unloading experiments of DN gels. The proposed model contains a few numbers of material constants and shows a good agreement with cyclic uni-axial test data.

scholarly journals Temperature dependent analytical model for submicron GaAs-MESFET

2021 ◽  
Vol 10 (3) ◽  
pp. 1271-1282
Author(s):  
Mohamed Djouder ◽  
Arezki Benfdila ◽  
Ahcene Lakhlef
Keyword(s):  
Analytical Model ◽  
Temperature Dependent ◽  
Gaas Mesfet ◽  
Voltage Variation ◽  
Proposed Model ◽  
Current Voltage ◽  
Current Voltage Characteristics ◽  
Simulation Results ◽  
Parameter Values ◽  
Good Agreement

MESFET are used in circuitsof gigahertz frequencies as they are based on gallium arsenide (GaAs) having electron mobility six times higher than that of silicon. An analytical model simulating different device current-voltage characteristics, i.e., output conductance and output transconductance of a 0.3μm gate MESFET with temperature dependence is proposed. The model is validated by comparing the results of the proposed model and those of the numerical simulation. The parameter values are computed using an intrinsic MESFET of two-dimensional geometry. In this work, the distribution of different output loads for varied applied voltages is considered. Simulation results obtainedunder temperature variation effectsfor load distribution and applied driven voltage variation are considered. The RMS and average errors between the different models and GaAs MESFET simulations are calculated to evidence the proposed model accuracy. This was demonstrated by a good agreement between the proposed model and the simulation results, which are found in good agreement. The simulation results obtained under temperature variations were discussed and found to complement those obtained in the literature. This clarifies the relevance of the suggested model analytical.

Thermomechanical Modelling of Direct-Drive Friction Welding Applying a Thermal Pseudo Mechanical Model for the Generation of Heat

2018 ◽  
Vol 767 ◽  
pp. 343-350
Author(s):  
Mads Rostgaard Sonne ◽  
Jesper Henri Hattel
Keyword(s):  
Friction Welding ◽  
Mechanical Model ◽  
Welding Process ◽  
Outer Diameter ◽  
Direct Drive ◽  
Compression Tests ◽  
Temperature Dependent ◽  
Thermomechanical Model ◽  
Friction Stir ◽  
Good Agreement

In the present work a 2D axisymmetric thermomechanical model of the direct-drive friction welding process is developed, taking the temperature dependent shear yield stress into account in the description of the heat generation, utilizing a recent thermal pseudo mechanical model originally developed for the friction stir welding (FSW) process. The model is implemented in ABAQUS/Explicit via a subroutine. The application in this case is joining of austenitic stainless steel rods with an outer diameter of 112 mm, used for manufacturing of exhaust gas valves for large two stroke marine engines. The material properties in terms of the temperature dependent flow stress curves used both in the thermal and the mechanical constitutive description are extracted from compression tests performed between 20 °C and 1200°C on a Gleeble 1500 thermomechanical simulator. Comparison between measured and simulated transient temperatures shows relatively good agreement and furthermore, the simulated deformations in terms of upsetting length and flash formation are also in good agreement with the observations from the experiment.

Drilling Thrust and Torque Prediction of Viscoplastic Materials

2006 ◽  
Author(s):  
Hossein Vaghefpour ◽  
Ali Nayebi
Keyword(s):  
Shear Zone ◽  
Cutting Forces ◽  
Material Flow ◽  
Thrust Force ◽  
Orthogonal Cutting ◽  
Thermomechanical Properties ◽  
Twist Drill ◽  
Proposed Model ◽  
Thrust And Torque ◽  
Good Agreement

A model for drilling of viscoplastic materials is presented. An analytical model is developed for predicting thrust force and torque in the drilling with a twist drill. The thermomechanical properties are accounted for describing the material flow in the primary shear zone and at the element-chip interface. A temperature friction law is introduced. The approach is based on the representing the cutting forces along the cutting lips as a series of oblique elements. Similarly, cutting in the chisel region is treated as orthogonal cutting with different speeds depending on the radial location. The section forces obtained by the model are combined to determine the overall thrust force and drilling torque. The results of the proposed model are compared with experimental results and a good agreement is obtained.

Numerical Model for Thermal Cracking of Concrete

2007 ◽  
Vol 353-358 ◽  
pp. 941-944
Author(s):  
Shi Bin Tang ◽  
Chun An Tang ◽  
Zheng Zhao Liang ◽  
Qing Lei Yu
Keyword(s):  
Stress Concentration ◽  
Mechanical Model ◽  
Thermal Stresses ◽  
Damage Model ◽  
Thermal Mismatch ◽  
Concrete Failure ◽  
Proposed Model ◽  
Mesoscopic Level ◽  
Uniform Change ◽  
Good Agreement

Thermal stresses are identified as one of the major causes of concrete failure. In order to consider the heterogeneity of concrete at mesoscopic level, and to simulate its failure processes during temperature change, a coupled thermo-mechanical model, which is on the basis of statistical damage model, is proposed. The model revealed the effect of the heterogeneity on concrete, and by analysis one of the important thermal stresses, i.e. thermal mismatch stresses, which are caused by thermal mismatch between the aggregate and mortar due to uniform change in temperature, it indicate that the presence of thermal mismatch causes stress concentration along the interface between aggregate and mortar, and the superpose of those stresses cause the crack propagation in the line of the two aggregate. The crack patterns, simulated by the proposed model, show a good agreement with the experimental results.

FINE-TUNING OF MODELLING STRATEGY TO SIMULATE THERMO-MECHANICAL BEHAVIOUR OF DOUBLE FRICTION PENDULUM SEISMIC ISOLATORS UST ESTIMATOR

2019 ◽  
Vol 3 (Special Issue on First SACEE'19) ◽  
pp. 165-172
Author(s):  
Vincenzo Bianco ◽  
Giorgio Monti ◽  
Nicola Pio Belfiore
Keyword(s):  
Multibody Dynamics ◽  
Mechanical Behaviour ◽  
Mechanical Model ◽  
Dynamic Behaviour ◽  
Experimental Testing ◽  
Fine Tuning ◽  
Proposed Model ◽  
Modelling Techniques ◽  
Friction Pendulum

The use of friction pendulum devices has recently attracted the attention of both academic and professional engineers for the protection of structures in seismic areas. Although the effectiveness of these has been shown by the experimental testing carried out worldwide, many aspects still need to be investigated for further improvement and optimisation. A thermo-mechanical model of a double friction pendulum device (based on the most recent modelling techniques adopted in multibody dynamics) is presented in this paper. The proposed model is based on the observation that sliding may not take place as ideally as is indicated in the literature. On the contrary, the fulfilment of geometrical compatibility between the constitutive bodies (during an earthquake) suggests a very peculiar dynamic behaviour composed of a continuous alternation of sticking and slipping phases. The thermo-mechanical model of a double friction pendulum device (based on the most recent modelling techniques adopted in multibody dynamics) is presented. The process of fine-tuning of the selected modelling strategy (available to date) is also described.

scholarly journals A General Temperature-Dependent Stress–Strain Constitutive Model for Polymer-Bonded Composite Materials

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1393
Author(s):  
Xiaochang Duan ◽  
Hongwei Yuan ◽  
Wei Tang ◽  
Jingjing He ◽  
Xuefei Guan
Keyword(s):  
Composite Materials ◽  
Constitutive Model ◽  
Model Parameters ◽  
Temperature Dependent ◽  
Stress Strain ◽  
Proposed Model ◽  
Single Temperature ◽  
Testing Data ◽  
Bonded Composite ◽  
Tension And Compression

This study develops a general temperature-dependent stress–strain constitutive model for polymer-bonded composite materials, allowing for the prediction of deformation behaviors under tension and compression in the testing temperature range. Laboratory testing of the material specimens in uniaxial tension and compression at multiple temperatures ranging from −40 ∘C to 75 ∘C is performed. The testing data reveal that the stress–strain response can be divided into two general regimes, namely, a short elastic part followed by the plastic part; therefore, the Ramberg–Osgood relationship is proposed to build the stress–strain constitutive model at a single temperature. By correlating the model parameters with the corresponding temperature using a response surface, a general temperature-dependent stress–strain constitutive model is established. The effectiveness and accuracy of the proposed model are validated using several independent sets of testing data and third-party data. The performance of the proposed model is compared with an existing reference model. The validation and comparison results show that the proposed model has a lower number of parameters and yields smaller relative errors. The proposed constitutive model is further implemented as a user material routine in a finite element package. A simple structural example using the developed user material is presented and its accuracy is verified.

scholarly journals Compact Modelling of Electrical, Optical and Thermal Properties of Multi-Colour Power LEDs Operating on a Common PCB

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1286
Author(s):  
Krzysztof Górecki ◽  
Przemysław Ptak
Keyword(s):  
Integrated Circuits ◽  
Optical Model ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Junction Temperature ◽  
Optical Parameters ◽  
Spice Simulation ◽  
Light Emitting ◽  
Proposed Model ◽  
Good Agreement

This paper concerns the problem of modelling electrical, thermal and optical properties of multi-colour power light-emitting diodes (LEDs) situated on a common PCB (Printed Circuit Board). A new form of electro-thermo-optical model of such power LEDs is proposed in the form of a subcircuit for SPICE (Simulation Program with Integrated Circuits Emphasis). With the use of this model, the currents and voltages of the considered devices, their junction temperature and selected radiometric parameters can be calculated, taking into account self-heating phenomena in each LED and mutual thermal couplings between each pair of the considered devices. The form of the formulated model is described, and a manner of parameter estimation is also proposed. The correctness and usefulness of the proposed model are verified experimentally for six power LEDs emitting light of different colours and mounted on an experimental PCB prepared by the producer of the investigated devices. Verification was performed for the investigated diodes operating alone and together. Good agreement between the results of measurements and computations was obtained. It was also proved that the main thermal and optical parameters of the investigated LEDs depend on a dominant wavelength of the emitted light.

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