• Korean Journal of Materials Research
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• v.29 no.10
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• pp.603-608
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• 2019

Plastic waste is becoming a problem in various countries because of the difficulty of natural decomposition. One type is PET plastic(Polyethylene Terephthalate), which is often used as a bottle for soft drink packaging, and LDPE(Low Density Polyethylene), which is also widely used as a food or beverage packaging material. The use of these two types of plastic continuously, without good recycling, will have a negative impact on the environment. Building material waste is also becoming a serious environmental problem. This study aims to provide a solution to the problem of the above plastic waste and building material waste by making them into a mixture to be used as bricks. Research is carried out by mixing both materials, namely plastic heated at a temperature of $180-220^{\circ}C$ and building material waste that had been crushed and sized to 30-40 mesh with homogeneous stirring. The ratios of PET and LDPE plastic to building material waste are 9 : 1, 8 : 2, 7 : 3, 6 : 4 and 5 : 5. After heating and printing, density, water absorption and compressive strength tests are carried out. Addition of PET and LDPE plastic can increase compressive strength, and reduce water absorption, porosity and density. A maximum compressive strength of 10.5 MPa is obtained at the ratio of 6 : 4.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.4
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• pp.149-157
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• 2000

Computer simulations of the mechanical behavior of a three point bend specimen with a quarter notch under impact load are performed. The case with a load application point at the side is considered. An elastic-plastic von Mises material model is chosen. Three phases such as impact bouncing and bending phases are found to be identified during the period from the moment of impact to the estimated time for crack initiation. It is clearly shown that no plastic deformation near the crack tip is appeared at the impact phase. However it is confirmed that the plastic zone near the crack tip emerges in the second phase and the plastic hinge has been formed in the third phase. Gap opening displacement crack tip opening displacement and strain rate are compared with rate dependent material(visco-plastic material). The stability during various dynamic load can be seen by using the simulation of this study.

• Steel and Composite Structures
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• v.51 no.4
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• pp.377-389
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• 2024

In the present study, thermoelsatoplastic stresses and displacement for rotating hollow disks made of functionally graded materials (FGMs) has been investigated. The linear elastic-fully plastic condition is considered. The material properties except Poisson's ratio are assumed to vary in the radial direction as a power-law function. The heat conduction equation for the one-dimensional problem in cylindrical coordinates is used to obtain temperature distribution in the disk. The plastic model is based on the Tresca yield criterion and its associated flow rules under the assumption of perfectly plastic material behavior. Exact solutions of field equations for elastic and plastic deformations are obtained. It is shown that the elastoplastic response of the functionally graded (FG) disk is affected notably by the radial variation of material properties. It is also shown that, depending on material properties and disk dimensions, different modes of plastic deformation may occur.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.96-100
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• 2000

It is difficult to predict material behavior of forming process because the plastic instable flow phenomenon happens in practical forming process I. e. upsetting backward extrusion piercing indentation. In view of the direct relationship between instable material flow and quality defects of the products we should find out their phenomena, In this study we introduced the plastic spin and the kinematic hardening considering the kinematic hardening constitutive equation for rate-dependent material. Also analysis of upset forging is carried out using the rigid plastic FEM with Al7075

• Journal of the Semiconductor & Display Technology
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• v.21 no.3
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• pp.92-97
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• 2022

Plastics are classified into 7 types such as PET (PETE), HDPE, PVC, LDPE, PP, PS, and Other for separation and recycling. Recently, large corporations advocating ESG management are replacing them with bioplastics. Incineration and landfill of disposal of plastic waste are responsible for air pollution and destruction of the ecosystem. Because it is not easy to accurately classify plastic materials with the naked eye, automated system-based screening studies using various sensor technologies and AI-based software technologies have been conducted. In this paper, NIR scanning devices considering the NIR wavelength characteristics that appear differently for each plastic material and a system that can identify the type of plastic by learning the NIR spectrum data collected through it. The accuracy of plastic material identification was evaluated through a decision tree-based SVM model for multiclass classification on NIR spectral datasets for 8 types of plastic samples including biodegradable plastic.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.3
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• pp.361-371
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• 2000

RC structure is the composite material system combined concrete and steel showing different plastic behavior. Especially, concrete shows very complex plastic behavior. Therefore, for plastic analysis of RC structures, we have to model carefully each plastic behavior of concrete and steel member. But, because of divergency as well as difficulties and dimensions of modelling, it takes a lot of time and labor or sometimes it is impossible to perform plastic analysis of RC structures. In this study, for simplified plastic analysis of RC structures, we propose material transformation method by homogeneous and isotropic material which have the same plastic property as RC. We generate homogeneous and isotropic material showing the same moment-curvature curves (bi-linear stress-strain relation) as RC members, using bi-linear moment-curvature relation by yielding moment, yielding curvature and ultimate moment, ultimate curvature of RC member. Finally, we prove compatibility in the study by comparing plastic analysis results for various analysis models using transformed material models and RC model.

• Journal of the Korea Concrete Institute
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• v.22 no.6
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• pp.825-832
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• 2010

Although a critical section reaches its flexural strength in reinforced concrete structures, the structure does not always fail because moment redistribution occurs during the formation of plastic hinges. Inelastic deformation in a plastic hinge region results in plastic rotation. A plastic hinge mainly depends on material characteristics. In this study, a plastic hinge length and plastic rotation are evaluated using the flexural curvature distribution which is derived from the material models given in Eurocode 2. The influence on plastic capacity the limit values of the material model used, that is, ultimate strain of concrete and steel and hardening ratio of steel(k), are investigated. As results, it is appeared that a large ultimate strain of concrete and steel is resulting in large plastic capactiy and also as a hardening ratio of steel increases, the plastic rotation increases significantly. Therefore, a careful attention would be paid to determine the limit values of material characteristics in the RC structures.

• Computers and Concrete
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• v.26 no.3
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• pp.227-237
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• 2020

Strain rate investigations are needed to calibrate strain-rate-dependent material models and numerical codes. An appropriate material model, which considers the rate effects, need to be used for proper numerical modeling. The plastic concrete cut-off wall is a special underground structure that acts as a barrier to stop or reduce the groundwater flow. These structures might be subjected to different dynamic loads, especially earthquake. Deformability of a structure subjected to dynamic loads is a principal issue which need to be undertaken during the design phase of these structures. The characterization of plastic concrete behavior under different strain rates is essential for proper designing of cut-off walls subjected to dynamic loads. The Cowper-Symonds model, as one of the most commonly applied material models, complies well with the behavior of a plastic concretes in low to moderate strain rates and will be useful in explicit dynamics simulations. This paper aims to present the results of an experimental study on mechanical responses of one of the most useful types of plastic concrete and Cowper-Symonds constant determination procedures in a wide range of strain rate from 0.0005 to 107 (1/s). For this purpose, SHPB, uniaxial, and triaxial compression tests were done on plastic concrete samples. Based on the results of quasi-static and dynamic tests, the dynamic increase factors (DIF) of this material in different strain rates and stress state conditions were determined for calibration of the Cowper - Symonds material models.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_2
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• pp.961-968
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• 2022

Hydrogen embrittlement leads to the damages in bolts, nut, especially, high pressure valves, in the semiconductor facilities, hydrogen vehicles, hydrogen stations and so on. Monel material has higher strength than SUS material. Therefore, even though Monel material with special alloy is usually used to prevent the hydrogen embrittlement, it needs powerful drawing system to manufacture the rectangular or hexagonal bar using circular bar. The purpose of this study is to investigate the characteristics of plastic deformation of Monel material and 2 rollers of rolling unit in plastic limit through numerical analysis. As the results, it was predicted that, based on mean stress, as the rolling step was increased, the rolling force of rolling unit was decreased. In addition, the heat treatment for Monel material was needed because of residual stress due to plastic deformation. As for rollers, the roller was safe about 1.86 times compared with that of ultimate strength. In this study, as the roller 2 showed larger stress than roller 1, thus, roller 2 should be designed carefully to guarantee the safety. Further it was confirmed that the reaction force of roller could be helpful in bearing design.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.89-94
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• 2011

In this research, among thermoplasticity plastic raw material that recycling is possible polyolefine(TPO) and polyvinyl chloride(PVC) as target recycling plan examine wish to. It is polyolefine(TPO) and polyvinyl chloride(PVC)) is mediocrity material that there are a lot of amount useds among plastic material and it is material that recycling is also activated most. Long term made first new regulation raw material, by-product raw material happened at process of production at second factory and third time to examine recycling plan of this material divides this as raw material that pass through process separation and pelet Tuesday and analyzed each special quality removing each removed waste after is used. Measure tension strength and ext. heightening gradually mixing proportion of refreshing resources on standard Sample manufactured as new raw material and application examined possibility availability to single fly system.