scholarly journals Experimental Investigation of In-Plane Shear Behaviour of Thermoplastic Fibre-Reinforced Composites under Thermoforming Process Conditions

2021 ◽  
Vol 5 (9) ◽  
pp. 248
Author(s):  
Nikita Pyatov ◽  
Harish Karthi Natarajan ◽  
Tim A. Osswald
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Sheet Material ◽  
Matrix Material ◽  
Shear Behaviour ◽  
Temperature Cycle ◽  
Process Conditions ◽  
Cooling Rates ◽  
Dsc Measurements ◽  
Thermoforming Process

In order to meet environmental regulations and achieve resource efficiency in the series production of vehicles, recyclable polymer composites with a high strength-to-weight ratio are increasingly being used as materials for structural components. Particularly with thermoplastic fibre-reinforced polymers or organo-sheets, the advantage lies in the tailored mechanical properties of the final component by adapting the orientation of fibres based on the direction of loads. These components produced by thermoforming organo-sheets also offer a cost benefit and short cycle times. During the thermoforming process, the shear behaviour of the organo-sheet is the most dominant and determines the mechanical properties and quality of the resulting component. However, the current standard for characterising the shear behaviour of organo-sheets does not consider the strain and cooling rates inherent in the thermoforming process. This research investigates the influence of thermoforming process parameters on the shear behaviour of organo-sheets with a new methodology combining DSC and DMA experiments. During the thermoforming process, the transition of the matrix material from a molten state to a solid state is dictated by the crystallisation kinetics and their dependence on heating and cooling rates. Thus, non-isothermal DSC scans, which correspond to a temperature cycle in a thermoforming process, are used in the DSC experiments to establish the relationship between the recrystallisation temperature of the organo-sheet material and the cooling/heating rates in the thermoforming process. In order to achieve thermoforming-process-relevant cooling rates, fast scanning calorimetry (Flash DSC) is used in addition to conventional DSC measurements. DMA experiments carried out with 45° fibre orientation show that the recrystallisation temperature consequently influences the shear storage modulus of the organo-sheet. The results from DSC measurements show a shift of recrystallisation temperatures to lower temperatures as the cooling rate increases. The combined analysis of results from the DSC and DMA experiments supports the findings and shows the influence of the process temperature, cooling rate and strain rate on the recrystallisation temperature and, in turn, the shear behaviour of organo-sheets. Thus, a recommendation for establishing a new standard for characterising the shear behaviour of organo-sheets is made.

Effect of Ultra-Fast Cooling Rate on the Microstructure and Mechanical Properties of High Strength Cold-Rolled Sheet under Continuous Annealing

2018 ◽  
Vol 913 ◽  
pp. 311-316
Author(s):  
Kai Zhang ◽  
Ren Bo Song ◽  
Feng Gao ◽  
Wen Jie Niu ◽  
Chi Chen
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Cooling Rate ◽  
High Strength ◽  
Rolled Sheet ◽  
Cooling Rates ◽  
Microstructure And Mechanical Properties ◽  
Average Grain Size ◽  
Cold Rolled ◽  
Fast Cooling

The effect of different fast cooling rates on the microstructure and mechanical properties of the V and Ti microalloyed high strength cold-rolled sheet was studied under laboratory conditions. Five different fast cooling rates were set up as 20°C/s, 50°C/s, 200°C/s, 500°C/s and 1000°C/s, respectively. Optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the microstructure, and the mechanical properties were also tested. The results showed that with the increase of fast cooling rate from 20°C/s to 1000°C/s, the grains of martensite and ferrite were finer, and the average grain size of both martensite and ferrite decreased from 7.7μm to 3.9μm. The proportion of ferrite in the two phases decreased while that of the martensite increased from 25.7% to 62.1%. The morphology of martensite tended to be lath, and the density of dislocation in the ferrite grains nearby the martensite gradually increased. With cooling rate rising from 20°C/s to 1000°C/s, the yield strength of the experimental steel increased from 381MPa to 1074MPa, and the tensile strength increased from 887MPa to 1199MPa. And the elongation decreased from 14.2% to 7.2%, and the product of strength and elongation decreased from 12.6GPa·% to 8.6GPa·%.

Structure and Properties of Leaded Tin Bronze under Different Crystallization Conditions

2013 ◽  
Vol 872 ◽  
pp. 89-93 ◽  
Author(s):  
Nikita Martyushev ◽  
Ilya V. Semenkov ◽  
Yuriy N. Petrenko
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Cooling Rate ◽  
Structure And Properties ◽  
Cooling Rates ◽  
Tin Bronze ◽  
Microstructure Parameters ◽  
Influence Of Crystallization ◽  
Crystallization Conditions ◽  
High Cooling Rates

The influence of crystallization conditions of leaded tin bronze on the obtained microstructure parameters is examined in the paper. Modification of crystallization conditions was realised by varying the cooling rate of the melt with preheating of the casting molds. Quantitative regularities of the influence of the cooling rate of bronze on its phase composition are presented. Data on mechanical properties of the material under investigation are also reported in the paper. It is demonstrated that high cooling rates (casting into mold at ambient temperature) enable obtaining higher mechanical properties in comparison with low cooling rates (casting into mold heated up to 800 °С).

scholarly journals Effect of cooling rates after annealing on the microstructure and properties of 1000MPa grade automobile steel for cold forming

2021 ◽  
Author(s):  
Ruifeng Dong ◽  
Qingbo Zhao ◽  
Xiaohong Bi ◽  
Deng Xiangtao ◽  
Wentian Shen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Cooling Rate ◽  
Testing Machine ◽  
Phase Region ◽  
Two Phase ◽  
Tensile Testing Machine ◽  
Cooling Rates ◽  
Cold Forming ◽  
Automobile Steel

Abstract The effects of different cooling rates ( 0.05℃/s, 0.1℃/s, and 0.2℃/s ) on the microstructure and mechanical properties of 1000 MPa grade automobile steel for cold forming after two-phase annealing were studied. The microstructure of the experimental steel was observed by SEM and TEM, and its mechanical properties were tested by a universal tensile testing machine. The results showed that by increasing the cooling rate of two-phase annealing, more massive retained austenite, more uniform and fine ferrite, better elongation and higher ultimate tensile strength of steel can be obtained, so as to obtain better production of tensile strength and total elongation ( product of tensile strength and elongation, PSE ). The final result shows that after the test steel is quenched at 800℃ + 10 minutes and annealed in the two-phase region at 690℃ + 10 minutes, the faster the cooling rate, the better the mechanical properties. The mechanical properties of the steel plate are the best when the cooling rate reaches 0.2℃/s, and PSE can reach 27.44 GPa·%.

Improvement of Mechanical Properties of Fe-Cr-Mo-[Cu-Ni]-C Sintered Sintered Steels by Sinter Hardening

2011 ◽  
Vol 672 ◽  
pp. 31-38 ◽  
Author(s):  
Eva Dudrová ◽  
Marco Actis Grande ◽  
Mario Rosso ◽  
Margita Kabátová ◽  
Róbert Bidulský ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Chemical Composition ◽  
Cooling Rate ◽  
Impact Energy ◽  
Vacuum Sintering ◽  
Cooling Rates ◽  
Sintered Steels ◽  
Conventional Sintering

The effect of high temperature sintering and high cooling rate on shifting the microstructural composition to the favourably of martensite-bainite structures and thus effective improvement of mechanical properties of sintered steels based on Astaloy CrL powder with an addition of 1 and 2% Cu or 50% Distaloy AB powder and 0.65% C was investigated. All the systems were processed by both sinter-hardening and conventional sintering. The vacuum sintering at high-temperature of 1240 0C and at common temperature of 1180 0C were integrated with high (6 0C/s), medium (3 0C/s) and slow (0.1 0C/s) cooling rates; conventional sintering at 1180 0C with cooling rate of ~0.17 0C/s was carried out in a N2+10%H2 atmosphere. In dependence on chemical composition, the yield and tensile strengths of 890-1150 MPa and 913-1230 MPa respectively and impact energy of 10-15 J were achieved by sinter-hardening. The yield and tensile strengths are approximately double than those resulting from conventional sintering.

Predicting the effect of cooling rate on the mechanical properties of glass fiber–polypropylene composites using artificial neural networks

2018 ◽  
Vol 32 (9) ◽  
pp. 1268-1281 ◽  
Author(s):  
Mohammed S Kabbani ◽  
Hany A El Kadi
Keyword(s):  
Mechanical Properties ◽  
Neural Networks ◽  
Artificial Neural Networks ◽  
Glass Fiber ◽  
Cooling Rate ◽  
Cooling Rates ◽  
Polypropylene Composites ◽  
Unidirectional Glass ◽  
Static Tensile ◽  
Artificial Neural

Properties of thermoplastic-based composites are affected by their processing conditions, and understanding their behavior under these different conditions is of most importance. The current study aims to predict the static tensile behavior of unidirectional glass fiber–polypropylene composite materials processed under different cooling rates using artificial neural networks (ANNs). Stress–strain relations for the material processed under various cooling rates were predicted using ANN. For all the cases investigated, the modulus of elasticity was predicted with a minimum accuracy of 97%, while the ultimate strain was predicted, in most cases, with a minimum accuracy of 90%. These predictions indicate that ANN can be successfully used to predict the mechanical properties of unidirectional composites manufactured under different cooling rates. This method allows users to predict the behavior of the material under cooling rate conditions for which no experimental data are available.

scholarly journals Effect of Cooling Rates on the Microstructure and Mechanical Property of La Modified Al7SiMg Alloys Processed by Gravity Die Casting and Semi-Solid Die Casting

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 549
Author(s):  
Longfei Li ◽  
Daquan Li ◽  
Jian Feng ◽  
Yongzhong Zhang ◽  
Yonglin Kang
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Die Casting ◽  
Casting Process ◽  
Cooling Rates ◽  
Eutectic Si ◽  
Fibrous Morphology ◽  
La Addition ◽  
Semi Solid ◽  
Re Elements

Rare earth (RE) additions are capable of refining the α-Al phase as well as modifying the eutectic Si particles of alloys. The cooling rate in casting process should be carefully concerned when the Al-Si alloys are refined and modified by adding RE elements. In this study, the effect of cooling rates on the microstructure and mechanical properties of La modified Al-7.0Si-0.3Mg alloys was studied in gravity die casting and semi-solid die casting. It is found that in La modified Al-7.0Si-0.3Mg alloys, with increasing the cooling rate from 0.2 to 9 K/s in gravity die casting, the α-Al grains are greatly refined and the Si particles are modified to branching morphology, which evidently increases the UTS and elongation of alloys. In addition, when increasing the cooling rate from 30 to 130 K/s in semi-solid die casting, the α-Al grains are refined from 140 to 47 μm, and the Si particles are modified to fibrous morphology, which increases the UTS from 190 to 230 MPa and elongation from 10% to 11%. However, the 0.4 wt.% La addition results to La-rich phases formed in microstructure, which impairs the mechanical properties of Al-7.0Si-0.3Mg alloys in semi-solid die casting.

scholarly journals Development of recommendations on cooling rates of railway wheels with the use of modeling in the software package qform vx 8.2 for the formation of a homogeneous ferritic-perlite structure

2021 ◽  
Vol 3 (134) ◽  
pp. 13-22
Author(s):  
Alexander Babachenko ◽  
Ganna Kononenko ◽  
Evgen Klemeshov ◽  
Rostislav Podolskyi
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Cooling Rate ◽  
Software Package ◽  
Accelerated Cooling ◽  
Cooling Rates ◽  
Permissible Range ◽  
Thermal Section ◽  
High Set ◽  
Railway Wheels

The tests were performed on ER7 steel according to EN 13262. Based on the hardenability test (GOST 5657) by the method of end hardening (Jomen) the distance from the surface from which unilateral cooling was performed, where the hardness met the requirements of regulatory documentation for wheels of test steel, and the distance where the formation of needle structures, including bainite and otmanshtette, no longer took place. Simulation was applied in the software package QForm VX 8.2, as a result, a model was developed, for the adaptation of which the results of the experiment were used. Confirmed the high convergence of the results of the calculation and the experiment. At the same time, the model allowed to obtain an instantaneous cooling rate in a form that is more in line with the physical meaning of the process and to avoid the scatter of actual values associated with the discreteness of data capture. It is established that the instantaneous cooling rate changes in the process of continuous uniform supply of the cooler. The permissible range of cooling rates of the surface and central sections of the wheel rim during accelerated cooling of ER7 steel is determined. The data can be used to improve the heat treatment modes of railway wheels of current production in order to achieve a high set of mechanical properties both with the existing cooling technology and with differentiated cooling on the modernized equipment of the thermal section of the wheel shop. The developed model can be used to build thermokinetic diagrams under continuous cooling and to develop recommendations for heat treatment modes to achieve the specified mechanical properties under a certain structural state.

scholarly journals Influence of the cooling behaviour on mechanical properties of carbon fibre-reinforced thermoplastic/metal laminates

2018 ◽  
Vol 1 (2) ◽  
Author(s):  
Camilo Zopp ◽  
Daisy Nestler ◽  
Nadine Buschner ◽  
Carola Mende ◽  
Sven Mauersberger ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Fibre ◽  
Cooling Rate ◽  
Thermoplastic Polyurethane ◽  
Polyamide 6 ◽  
Shear Properties ◽  
Cooling Rates ◽  
Hybrid Laminates ◽  
Fast Cooling ◽  
Interlaminar Shear

For several years, thermoplastic hybrid laminates form a new class in the field of material compounds. These laminates consist of fibre-reinforced plastic prepregs and metal layers in alternating order. Compared to conventional thermosetting multilayer composites, these laminates are suitable for large-scale production and can be manufactured with significantly reduced cycle times in the thermoforming process.  In the framework of this contribution, the influence of the cooling rate of carbon fibre-reinforced thermoplastic composites and hybrid laminates was investigated with regard to crystallinity and the resulting mechanical properties. Polyamide 6 and thermoplastic polyurethane as matrix systems were examined, in particular.Additionally, the differential scanning calorimetry was used in order to investigate the influence of the cooling rate on the crystallisation behaviour. It could be determined that the cooling rate has a limited influence on the crystallisation of polyamide 6 and this influences the mechanical properties. Furthermore, a reliance of process parameters on the characteristics profile of composite materials and material compounds with thermoplastic polyurethane could be identified. Depending on process conditions, tensile, bending, and interlaminar shear properties fluctuate up to 20 % in fibre-reinforced laminates and up to 32 % in hybrid laminates. Moderate to fast cooling rates result in optimum mechanical characteristics of tensile properties in fibre-plastic-compounds. Fast to very fast cooling rates are advisable for bending and interlaminar shear properties. Highest tensile and bending characteristics are achieved in hybrid laminates by using fast to very fast cooling rates, while interlaminar shear properties tend to be highest in slow to moderate cooling rates.

Effect of Cooling Rate on the Microstructure and Mechanical Properties of Sn-0.7wt.%Cu Solder Alloy

2016 ◽  
Vol 675-676 ◽  
pp. 513-516 ◽  
Author(s):  
Phairote Sungkhaphaitoon ◽  
Thawatchai Plookphol
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Cooling Rate ◽  
Solder Alloy ◽  
Solder Alloys ◽  
Cooling Systems ◽  
Cooling Rates ◽  
Microstructure And Mechanical Properties ◽  
Two Phases

The dependence of microstructure and mechanical properties of Sn-0.7wt.%Cu solder alloys on different cooling rates were investigated. Two cooling rates were employed during solidification: 0.04 °C/s (mold-cooled system) and 1.66 °C/s (water-cooled system). The results showed that the ultimate tensile strength of Sn-0.7wt.%Cu solder alloy increased but the elongation decreased when water-cooled system was used. The microstructure of Sn-0.7wt.%Cu solder alloys solidified by both cooling systems exhibited two phases of Sn-rich and Cu6Sn5 intermetallic compounds (IMCs). However, finer grains were observed in the water-cooled specimens.

Effect of laser inclination angle on mechanical properties of Hastelloy X processed by selective laser melting

2021 ◽  
Vol 63 (1) ◽  
pp. 10-16
Author(s):  
Zong Xuewen ◽  
Zhang Jian ◽  
Fu Hanguang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Temperature Field ◽  
Yield Strength ◽  
Cooling Rate ◽  
Selective Laser Melting ◽  
Inclination Angle ◽  
Laser Melting ◽  
Cooling Rates ◽  
Hastelloy X

Abstract Selective laser melting at various laser inclination angles was used to prepare Hastelloy X alloy specimens. The morphology, fracture, tensile strength, stress, and strain of Hastelloy X alloy specimens were studied using optical microscopy, scanning electron microscopy, and a tensile tester. The temperature field of the manufacturing process was analyzed based on finite element analysis, and the internal relationship between the temperature field and the process was constructed in terms of cooling speed. The results show that the temperature field is a dynamic process with a high cooling rate; the average cooling rate reaches 3.23 × 106 °C × s−1. The greater the inclination angle, the greater the thermal gradient, resulting in higher cooling rates. Due to the cross-influence of grain refinement at high cooling rates and residual stress, the tensile strength and yield strength of Hastelloy X alloy showed first increasing and then decreasing trends with respect to inclination angle. However, at an inclination angle of 30°, the voids and crack defects of Hastelloy X alloy fractures were reduced, and the tensile strength and yield strength reached 881.38 and 701.60 MPa, respectively. At this angle, the mechanical properties were excellent and met the requirements of the aviation industry.

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