Percentage Of Thickness Reduction Research Articles

Creep and thermal ratcheting characterization of polytetrafluoroethylene-based gasket materials

Characterization of Teflon polymer based gaskets under expedited aging is the objective of this work. Teflon gaskets are exploited frequently as a replacement to asbestos fiber gaskets because of their excellent leak tightness and nonhazardous physical degradation properties. The research focuses profoundly on the adverse influence of temperature and thermal cycles on the creep and cumulative damage phenomenon under compressive load. Virgin and expanded PolyTetraFluoroEthylene (PTFE) are tested under 28 and 41 MPa of gasket stress at different temperatures. Intricate analysis of creep under coalesces of thermal ratcheting and principal stress is achieved through Universal Gasket Rig (UGR). The instigated cumulative damage is distinguishable into upper and lower bound temperature region indicating the escalation and decrease of thickness change during cycling which saturates after 12 thermal cycles for expanded PTFE while no saturation is reached for virgin PTFE in even after 20 thermal cycles. Percentage of thickness reduction at different applied stress is nearly the same for virgin PTFE whereas expanded PTFE shows largest reduction under lower stress. Compressive creep bespeaks the impact of temperature and load, thereby dictating the magnitude of ratcheting damage and contrariwise. Finally, the creep and thermal ratcheting has a proliferating effect on value of the coefficient of thermal expansion for all chosen gaskets. Copyright © 2017 VBRI Press.

Forming of hemispherical and hemi-ellipsoidal parts of low carbon steel sheet by mandrel free metal spinning process

Metal spinning (MS) is an efficient and economical alternative method for low-volume functional sheet metal products. It has higher potential to shape three dimensional parts without employing matching die. The focus in advancement of shape forming shall bring an effective approach to produce defect free shapes and economically viable products. This paper is going to discuss about the modification in the MS process, without using matching dies or mandrel to produce a hemispherical and hemi-ellipsoidal profile product. The forming occurs by the deformation of sheet metal when the roller feed is against the rotating metal blank. Low carbon extra deep drawing Al killed steel sheets of thickness 1.6 mm were exploited as forming material. Further the paper illustrates on thickness variation, hardness, micro-structure, surface roughness and forming limit diagram (FLD) of the various zone of the formed part. It is examined that as the depth varies, the changes in thickness of formed part also varies. Also, the surface roughness was proportionally increased with increasing in percentage of reduction in thickness. In all zone of the formed steel part are in tension- tension strain conditions, there is no tension compression and plane strain condition occurred in the forming process. Due to this reason wrinkles failure is eliminated in die less MS process.

Characterization of spray formed and cold rolled Al-Pb alloy

The Al-Pb alloys were spray formed in the form of a disc shape by using the nozzle and their characteristics such as microstructure, porosity, hardness wear etc were studied. The spray droplets were deposited over a copper substrate to achieve a disc shape perform. The porosity, hardness, wear and micro structural studies of the Al-Pb spray deposited alloys were conducted for 20% lead content in aluminum after the cold rolling process for 20%, 40%, 60% and 80% of the thickness reduction from the top to peripheral region and Optical micrographs were taken for the samples with different percentage of thickness reduction from top to peripheral regions. In scanning electron micrograph the grain boundaries were clear with the 20% of the lead content and max amount of lead content was distributed along the grain boundaries. The lead was uniformly dispersed in the deposit as revealed by colour dot map. The surface porosity and total porosity increases with increase in the percentage of the reduction in thickness of the samples. The hardness increased in middle and peripheral regions due to increase in the percentage of reduction in thickness of the samples. Friction and wear testing of spray formed alloys were investigated using a pin on disc type wear testing machine.wear rate behaviour with applied load was observed.

Neural network-based expert system for modeling of tube spinning process

The present paper deals with the development of neural network (NN)-based expert system for modeling of 2024 aluminum tube spinning process. Tube spinning is a highly nonlinear thermo-mechanical process for producing large-diameter thin-walled shapes. It is interesting to note that the performance of the process depends on various process parameters, such as wall thickness, percentage of thickness reduction, feed rate, mandrel rotational speed, solution treatment time and aging time. Therefore, an NN-based expert system is necessary for modeling the tube spinning process. The input layer of NN consists of six neurons corresponding to the inputs of the tube spinning process. Moreover, the output layer consists of four neurons that represent four responses, namely change in diameter, change in thickness, inner and outer surface roughness. It is to be noted that the performance of NN depends on various factors, such as number of neurons in the hidden layer, coefficients of transfer functions and connecting weights, etc. In the present paper, three algorithms, such as back-propagation, genetic and artificial bee colony algorithms, are used for optimizing the said variables of NN. Further, the developed approaches are tested for their accuracy in prediction with the help of some test cases and found to model the tube spinning process effectively.

Optimization of Force and Power Imposed on Continuous Tandem Cold Rolling Rollers Using a Multiple-Function Genetic Algorithm

The amount of energy consumed in the production lines such as cold rolled process is one of the fundamental problems in the energy infrastructure of manufacturing sectors. Accordingly, much attention should be directed towards optimizing the power consumption of production lines using reasonable methods. Furthermore, the powers exerted on such equipment must be modified to find an optimized energy consumption level. This study tries to examine the optimization of forces and powers imposed on the continuous tandem cold rolling rollers of metal sheets using MATLAB and genetic algorithm. Firstly, some relationships and calculations of rolled metal sheets are analyzed. Then parameters, such as percentage of thickness reduction, mean pressure, yield stress, power of rollers and exerted torque, are calculated. All the governing relationships are programmed using MATLAB software. Having compared the mentioned two methods, genetic algorithm is used to determine the optimal required power. The results show that the optimized powers generated by genetic algorithm method are in good agreement with experimental observations. Also, the powers of rolling rollers and standard deviations of powers are calculated and, then, the two functions are compared and the optimum point between them is optimized.

SIFAT FISIS DAN MEKANIS BATANG KELAPA (Cocos nucifera L.) DENGAN PROSES PEMADATAN

This study aims to determine the physical and mechanical properties of coconut trunks based on 4 factors of acacia bark extract concentrations (0%, 10%, 15%, 20%) and the percentage of reduction in thickness (0%, 30%, 40%, 50%). The results showed that the average value of coconut wood moisture content is not compacted relatively higher compare to the average levels of condensed water. The average value of the coconut wood density was not relatively lower compared to the average density of the compacted. The average value of MOR and MOE coconut wood once compacted experience increased with coconut wood are not compressed. But all the values MOR coconut wood on this study is classified into strong wood class V. From the results of this study concluded that the process of compacting the coconut wood and soaking treatment using the extract of acacia bark may increase the value of physical and mechanical properties of coconut wood. Coconut wood compaction technology can be utilized as a substitute for wood raw materials but can not be used to hold the load.Keywords : coconut wood, physical properties, mechanical properties

Effect in the high modulus asphalt concrete with the temperature

The use of the high modulus asphalt concrete in the base course of airport pavements is not of recent utilization, but at present there is a considerable gap in the regulation for the use of this bitumen. The main objective of this paper is to present the results of the research that has been done using the experimental dynamic modulus of different mixtures of conventional bitumen with different penetration index B40/50, B60/70, B100/150, B150/200 and the high modulus bitumen B13/22 to calculate the percentage of reduction in thickness of the base course in airport pavements when is used High Modulus Asphalt Concrete (HMAC) compare with conventional bitumen mixtures and is also taken into account the temperature. In order to obtain the reduction in thickness depending on the temperature and the use of HMAC, the tests have been performed at the different temperatures −20°C, −10°C, 0°C, 10°C, 20°C and all the results in this paper are presented for these temperatures.To perform the calculations of this research the Airbus A380 has been taken as Aircraft Design.

Weighted Average-Based Multi-Objective Optimization of Tube Spinning Process using Non-Traditional Optimization Techniques

Tube spinning is an effective process for producing long and thin walled tubes. It is important to note that the quality of parts produced in tube spinning process, namely internal surface roughness, external surface roughness, change in diameter and change in thickness depends on the right combination of input process parameters, such as mandrel rotational speed, feed rate of rollers, percentage of thickness reduction, initial thickness, solution treatment time and ageing treatment time. As the 2024 aluminum tube spinning process contains four objectives, it is very difficult to achieve a set of optimal combination of input process parameters that produce best quality product. This paper presents a weighted average-based multi-objective optimization of tube spinning process using non-traditional optimization techniques, namely genetic algorithm, particle swarm optimization and differential evolution. Multiple regression equations developed between the control factors and responses have been considered for optimization.

Simulation of Cold Rolling Process Using Smoothed Particle Hydrodynamics (SPH)

Regarding the reported capabilities and the simplifications of the smoothed particle hydrodynamics (SPH) method, as a mesh-free technique in numerical simulations of the deformation processes, a 2-D approach on cold rolling process was provided. Using and examining SPH on rolling process not only caused some minor developments on SPH techniques but revealed some physical realities. The chosen test case for rolling is an aluminum strip: Al 6061. In this way, the rolls assumed to behave as rigid bodies and, the aluminum strip assumed to behave as an elastic-plastic continuum. In order to achieve the required assurance of the employed technique, the computed stress distribution patterns were compared with those reported from a finite element study, and the results showed good agreements. Moreover, as the final main test, the effect of some affective parameters; roll diameter, percentage of thickness reduction of the strip, and the rolling speed has been studied. In current study not only some developments of using the SPH technique were achieved, but also, could present the capability of the SPH for more simple numerical approaches for such complicated deformation processes.

The influence of Rolling process on the porosity and wear behavior of Spray-formed Al-6%Si-20%Pb

Spray forming, also called spray casting or spray deposition, is the inert gas atomization of a liquid metal stream into variously sized droplets. These droplets are interrupted by a substrate which collects and solidifies the droplets into coherent, near fully dense perform. The present work concerns with this techniques. This technology was applied to produce Al-6%Si-20%Pb alloys. The spray droplets were deposited over a copper substrate to achieve a disc shape perform. After spray deposition samples were rolled at room temperature on two high rolling mills and total porosity and wear characteristic of spray deposits were studies. The total porosity decreases with the increase in the percentage of reduction in thickness of the samples. Thickness of the samples in both middle and peripheral region. Wear testing of spray formed and rolled Al-Si- Pb alloy were investigated on a pin on disc type wear machine. Wear rate behavior with applied load and increase in percentage of reduction in thickness of samples was observed. Wear rate increased with increasing the load and decreased with increase in percentage of reduction in thickness of the sample. Keyword: Al-Si-Pb alloy, Rolling, Spray forming, Total porosity, Wear characteristic

Effect of Cold Rolling on the Mechanical Properties of Spray Cast Al-6Si-20Pb Alloy

Porosity, hardness and microstructural studies of cold rolled spray cast Al-6Si-20Pb alloy for different percentage of thickness reduction were conducted from top to bottom and from centre to periphery of the deposit. Porosity was found to decrease and hardness was found to increase with the increase in percentage of thickness reduction. Aluminum grains were observed to become coarser with the increase in percentage of thickness reduction.

Application of artificial neural networks for the prediction of roll force and roll torque in hot strip rolling process

This paper introduces an artificial neural network (ANN) application to a hot strip mill to improve the model’s prediction ability for rolling force and rolling torque, as a function of various process parameters. To obtain a data basis for training and validation of the neural network, numerous three dimensional finite element simulations were carried out for different sets of process variables. Experimental data were compared with the finite element predictions to verify the model accuracy. The input variables are selected to be rolling speed, percentage of thickness reduction, initial temperature of the strip and friction coefficient in the contact area. A comprehensive analysis of the prediction errors of roll force and roll torque made by the ANN is presented. Model responses analysis is also conducted to enhance the understanding of the behavior of the NN model. The resulted ANN model is feasible for on-line control and rolling schedule optimization, and can be easily extended to cover different aluminum grades and strip sizes in a straight-forward way by generating the corresponding training data from a FE model.

Improvement of Fracture Toughness (K<sub>1c</sub>) of 7075 Al Alloy by Cryorolling Process

The effects of cryorolling (Rolling at liquid nitrogen temperature) and optimum heat treatment (short annealing + ageing) on fracture toughness of 7075 Al alloy are reported in the present work. The Al 7075 alloy was rolled for different thickness reductions (40% and 70%) at cryogenic temperature and its mechanical, fracture toughness properties were studied. The microstructural characterization of the alloy was carried out by using Optical microscopy and Field emission scanning electron microscopy (FESEM). The cryo-rolled (CR) Al alloy after 70% thickness reduction exhibits ultrafine grain structure as observed from its FESEM micrographs. It is observed that the yield strength and fracture toughness of the CR material with 70% thickness reduction have increased by 108% and 73% respectively, compared to the starting material. The CR 7075 Al alloy shows improved fracture toughness and tensile strength due to high dislocation density, grain refinement, and ultrafine-grain (UFG) formation by multiple cryorolling passes. The CR samples were subjected to short annealing for 5 min at 190 0C, 170 0C and 150 0C followed by ageing at 160 0C, 140 0C and 120 0C for both 40% and 70% reduced samples. The combined effect of short annealing and ageing improves the fracture toughness, tensile strength, and ductility of cryorolled samples, which is due to precipitation hardening and subgrain coarsening mechanism respectively. The scanning electron microscopy (SEM) fractographs of the Al 7075 alloy samples reveals that starting bulk Al alloy specimens is fractured in a total ductile manner, consisting of well-developed dimples over the entire surface and dimple size got decreased continuously for cryorolled specimens at different percentage of thickness reduction (40% and 70%) as observed in the present work.

Modeling and Investigation of the Wall Thickness Changes and Process Time in Thermo-Mechanical Tube Spinning Process Using Design of Experiments

Tube spinning technology is one of the effective methods of manufacturing large diameter thin-walled shapes. In this research, effects of major parameters of thermo mechanical tube spinning process such as preform's thickness, percentage of thickness reduction, mandrel rotational speed, feed rate, solution treatment time and aging treatment time on the wall thickness changes and process time in thermo-mechanical tube spinning process for fabrication of 2024 aluminum spun tubes using design of experiments (DOE), are studied. The statistical results are verified through some experiments. Results of experimental evaluation are analyzed by variance analysis and mathematic models are obtained. Finally using these models, input parameters for optimum production are achieved.

Prediction of influence parameters on the hot rolling process using finite element method and neural network

In the present investigation, a hot rolling process of AA5083 aluminum alloy is simulated using the finite element method. The temperature distribution in the roll and the slab, the stress, strain and strain rate fields, are extracted throughout a steady-state analysis of the process. The main hypotheses adopted in the formulation are: the thermo-viscoplastic behavior of the material expressed by Perzyna constitutive equation and rolling under plane-deformation conditions. The main variables that characterize the rolling process, such as the geometry of the slab, load, rolling speed, percentage of thickness reduction, initial thickness of the slab and friction coefficient, have been expressed in a parametric form giving a good flexibility to the model. The convergence of the results has been evaluated using experimental and theoretical data available in the literature. Since the FE simulation of the process is a time-consuming procedure, an artificial neural network (ANN) has been designed based on the back propagation method. The outputs of the FE simulation of the problem are used for training the network and then, the network is employed for prediction of the behavior of the slab during the hot rolling process.

The Effect of 45° Rolling Process on the Mechanical Properties of P/M Rhenium

A novel processing technique which utilizes the 45° rolling mode is introduced. An optimum processing method of light rolling (10-12% reduction in thickness) along the 45° direction, followed by intermittent annealing (1650°C / 30 min. in H2 atmosphere) was carried out. The partial reduction and intermittent annealing were repeated until an 82.9% reduction was achieved with a tensile strength of 2388 MPa (346.6 Ksi) and 3.3% elongation. Additional experiments were performed to test the feasibility of increasing the percentage of reduction in thickness in cold rolling from the conventional 10-15% to 20-55% along the 45° direction. Although extensive microcracking occurred, intermediate strengths were achieved and ductility was retained. This processing technique has the potential of producing ultra high strength, very thin sheets, which are vital for space nuclear power applications and missile guidance systems.

Correction of Holocene sedimentation rates for mechanical compaction: the Tigris-Euphrates Delta, Lower Mesopotamia

Holocene sedimentation rates have been calculated for the lacustrine/deltaic deposits of Lower Mesopotamia. The calculations depend on the radiocarbon dating of five organic-rich borehole samples and four near-surface shelly samples. Rates between 1 and 1.8 mm/year were dominant throughout the Holocene from 8400 years BP until about 3000 years BP . During the later stage of the Holocene, rates of 0.4 mm/year were not exceeded. The role of near-surface overburden compaction was excluded in these calculations. Near-surface overburden compaction is an effective mechanical process, particularly for muddy deposits such as those of the Tigris-Euphrates Delta. However, such compaction is usually ignored by most petroleum geologists down to >100 m depth. A geotechnical approach was developed to measure the relative amount of this compaction and to correct the above-mentioned sedimentation rates geotechnically. Correction curves were established, based on laboratory consolidation tests, for the three dominant sedimentary types sand, silt and clay fractions. In addition, a general correction curve was derived based on the general distribution of these three types of sediment in the Holocene succession of the Tigris-Euphrates Delta. Each curve shows the relation between the percentage of thickness reduction, due to mechanical compaction, and depth. Thickness reductions of up to >25% have been determined, particularly within the first 5 m of the sedimentary column. Below this depth interval, the slope of the curves reduces down to 15 m depth and more. When the previously mentioned sedimentation rates were recalculated using the established curves they increased to 1.3–2.2 mm/year. Based on these latter calculations, it is essential for petroleum geologists to reassess the concept of near-surface overburden compaction.

Correction of Holocene sedimentation rates for mechanical compaction: the Tigris-Euphrates Delta, Lower Mesopotamia

Holocene sedimentation rates have been calculated for the lacustrine/deltaic deposits of Lower Mesopotamia. The calculations depend on the radiocarbon dating of five organic-rich borehole samples and four near-surface shelly samples. Rates between 1 and 1.8 mm/year were dominant throughout the Holocene from 8400 years BP until about 3000 years BP. During the later stage of the Holocene, rates of 0.4 mm/year were not exceeded. The role of near-surface overburden compaction was excluded in these calculations. Near-surface overburden compaction is an effective mechanical process, particularly for muddy deposits such as those of the Tigris-Euphrates Delta. However, such compaction is usually ignored by most petroleum geologists down to >100 m depth. A geotechnical approach was developed to measure the relative amount of this compaction and to correct the above-mentioned sedimentation rates geotechnically. Correction curves were established, based on laboratory consolidation tests, for the three dominant sedimentary types sand, silt and clay fractions. In addition, a general correction curve was derived based on the general distribution of these three types of sediment in the Holocene succession of the Tigris-Euphrates Delta. Each curve shows the relation between the percentage of thickness reduction, due to mechanical compaction, and depth. Thickness reductions of up to >25% have been determined, particularly within the first 5 m of the sedimentary column. Below this depth interval, the slope of the curves reduces down to 15 m depth and more. When the previously mentioned sedimentation rates were recalculated using the established curves they increased to 1.3–2.2 mm/year. Based on these latter calculations, it is essential for petroleum geologists to reassess the concept of near-surface overburden compaction.