The use of masonry infill wall for load bearing structures is quite common practice in low seismic zones, while in the high seismic zones these are used for partition walls only. The lack of seismic standards of masonry and lack of proper design parameters has made this construction practices totally empirical based. To give aesthetic architectural look, requirements of structural system increases and for the masonry construction this lacks with limited available data of design. Studies in the past have shown during earthquake masonry structures fail more in number than framed structures due to rough design and bad execution techniques. To improve the performance of masonry structures during earthquake, we need to understand its expected failures and reasons behind them. One of the failure i.e. in-plane and out of plane failure of masonry walls are very common. To improve this failure one need to improve the connection between the long wall and short wall. So that when earthquake comes, a rigid connection between walls can be introduced. This connection will help in providing resistance in between junction of long walls and short walls. When long wall faces earthquake, it comes under action of shear force and force tends to move its top portion away from its original position. If there is not properly designed key connection between these two walls, the long wall will fail at early age of loading. In case if there is strong key connection between these two walls, short wall will provide support to the long wall and increase its capacity to withstand an earthquake and vice versa. To ensure this rigid connection bricks are laid in bonds. But to make it more strong, one can use steel reinforcement in layer wise having Lshaped in plan at suitable vertical center to center distance also keeping economy in design. Resulted shear force, displacements, shear stresses and energy dissipation parameters satisfy the improved behavior of connection due to presence of steel reinforcement at suitable c/c vertical distance.
{"title":"To Investigate The Contribution Of Steel Reinforcement In Corner Region Of Masorny Wall For Improving Key Connection","authors":"S. Verma, Bibhas Paul","doi":"10.9790/1684-1403040114","DOIUrl":"https://doi.org/10.9790/1684-1403040114","url":null,"abstract":"The use of masonry infill wall for load bearing structures is quite common practice in low seismic zones, while in the high seismic zones these are used for partition walls only. The lack of seismic standards of masonry and lack of proper design parameters has made this construction practices totally empirical based. To give aesthetic architectural look, requirements of structural system increases and for the masonry construction this lacks with limited available data of design. Studies in the past have shown during earthquake masonry structures fail more in number than framed structures due to rough design and bad execution techniques. To improve the performance of masonry structures during earthquake, we need to understand its expected failures and reasons behind them. One of the failure i.e. in-plane and out of plane failure of masonry walls are very common. To improve this failure one need to improve the connection between the long wall and short wall. So that when earthquake comes, a rigid connection between walls can be introduced. This connection will help in providing resistance in between junction of long walls and short walls. When long wall faces earthquake, it comes under action of shear force and force tends to move its top portion away from its original position. If there is not properly designed key connection between these two walls, the long wall will fail at early age of loading. In case if there is strong key connection between these two walls, short wall will provide support to the long wall and increase its capacity to withstand an earthquake and vice versa. To ensure this rigid connection bricks are laid in bonds. But to make it more strong, one can use steel reinforcement in layer wise having Lshaped in plan at suitable vertical center to center distance also keeping economy in design. Resulted shear force, displacements, shear stresses and energy dissipation parameters satisfy the improved behavior of connection due to presence of steel reinforcement at suitable c/c vertical distance.","PeriodicalId":14565,"journal":{"name":"IOSR Journal of Mechanical and Civil Engineering","volume":"14 1","pages":"01-14"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87092407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-05-01DOI: 10.9790/1684-140301104107
A. Verma, Disha Srivastava
Cement is a fine binding material which sets and strengthens when water is supplemented to it. It is largely used in construction with great advantages but cement with its wide range of properties has several disadvantages as well. Manufacturing of cement causes ill effect on environment at all stages of process. These include emissions of pollutantslike dust, gas, noise and vibration. Manufacturing of cement causes emission of the most common greenhouse gas i.e. carbon dioxide, from 5% in cement structures to 8% in case of cement roads. Carbon dioxide is released by cement manufacturing both indirectly (emission of energy) and directly (heating of calcium carbonate). The cement factories produce upto 5% of global artificial CO2 emission. This review paper presents the usage of fly ash by replacement of cement in our general construction. In addition, review of effect of steel fibers on concrete is also done.
{"title":"A Review on Partial Replacement of Cement by Flyash and Effect of Steel Fibers","authors":"A. Verma, Disha Srivastava","doi":"10.9790/1684-140301104107","DOIUrl":"https://doi.org/10.9790/1684-140301104107","url":null,"abstract":"Cement is a fine binding material which sets and strengthens when water is supplemented to it. It is largely used in construction with great advantages but cement with its wide range of properties has several disadvantages as well. Manufacturing of cement causes ill effect on environment at all stages of process. These include emissions of pollutantslike dust, gas, noise and vibration. Manufacturing of cement causes emission of the most common greenhouse gas i.e. carbon dioxide, from 5% in cement structures to 8% in case of cement roads. Carbon dioxide is released by cement manufacturing both indirectly (emission of energy) and directly (heating of calcium carbonate). The cement factories produce upto 5% of global artificial CO2 emission. This review paper presents the usage of fly ash by replacement of cement in our general construction. In addition, review of effect of steel fibers on concrete is also done.","PeriodicalId":14565,"journal":{"name":"IOSR Journal of Mechanical and Civil Engineering","volume":"46 1","pages":"104-107"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88277255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Feature recognition has been always an important link between CAD and CAM. Feature recognition is applied in successive stages. Firstly, feature entities extraction should be applied, followed by an algorithm of how to relate the entities together. Finally, the feature recognition algorithm is applied. In this paper,a logic for identifying face-face interaction is applied. The type of face-face interaction is needed for further use in feature recognition. A methodology is introduced to determine the relation between faces. The relation iseither concave, convex or non-joined faces. The connected edge between the faces is determined, and the included angle is calculated to determine the relation between them. The algorithm has been implemented using java programming language. Case studies have been applied for prismatic parts and successfully identified face-face relation as illustrated and shown for different faces combinations.
{"title":"Identifying the Type of Face To Face Connection from STEP AP203 File","authors":"M. Koura, Asma Hamed","doi":"10.9790/1684-1403033742","DOIUrl":"https://doi.org/10.9790/1684-1403033742","url":null,"abstract":"Feature recognition has been always an important link between CAD and CAM. Feature recognition is applied in successive stages. Firstly, feature entities extraction should be applied, followed by an algorithm of how to relate the entities together. Finally, the feature recognition algorithm is applied. In this paper,a logic for identifying face-face interaction is applied. The type of face-face interaction is needed for further use in feature recognition. A methodology is introduced to determine the relation between faces. The relation iseither concave, convex or non-joined faces. The connected edge between the faces is determined, and the included angle is calculated to determine the relation between them. The algorithm has been implemented using java programming language. Case studies have been applied for prismatic parts and successfully identified face-face relation as illustrated and shown for different faces combinations.","PeriodicalId":14565,"journal":{"name":"IOSR Journal of Mechanical and Civil Engineering","volume":"28 1","pages":"37-42"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85901062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The research goal is the study of fiber content and fiber type influences on NSC compressive and tensile strengths. fiber type[(steel, polypropylene and glass ) and fiber content were studied. A constant water/binder equals to 0.45 and aconstant binder content =400kg/m 3 were used. the percentages of nano silica[NS] that replaced cement in this research were 0 and1.5%. Polypropylene fiber [PPF] with 12mm length and 4 dosages of 0%, 0.2%,0.4% and 06.% are used. Glass fiber [GF] with 18mm length and 4 dosages of 0%, 0.2%,0.4% and 06.% are also used. Steel fiber [SF] with 50mm length,0.5mm diameter and 4 dosages of 0%, 0.4%,0.8% and 1.2% are used. The results illustrated that 1.5%NS has improvement on normal concrete compressive and tensile strengths. Increasing of SF content from 0.4% to 1.2% has significant improvement on NSC compressive and tensile strengths. PPF and GF addition caused decreasing on NSC compressive and tensile strengths.
{"title":"The Effect of Fibers Type and Content on Nano Silica Concrete [Nsc]","authors":"K. Ibrahim","doi":"10.9790/1684-1402082734","DOIUrl":"https://doi.org/10.9790/1684-1402082734","url":null,"abstract":"The research goal is the study of fiber content and fiber type influences on NSC compressive and tensile strengths. fiber type[(steel, polypropylene and glass ) and fiber content were studied. A constant water/binder equals to 0.45 and aconstant binder content =400kg/m 3 were used. the percentages of nano silica[NS] that replaced cement in this research were 0 and1.5%. Polypropylene fiber [PPF] with 12mm length and 4 dosages of 0%, 0.2%,0.4% and 06.% are used. Glass fiber [GF] with 18mm length and 4 dosages of 0%, 0.2%,0.4% and 06.% are also used. Steel fiber [SF] with 50mm length,0.5mm diameter and 4 dosages of 0%, 0.4%,0.8% and 1.2% are used. The results illustrated that 1.5%NS has improvement on normal concrete compressive and tensile strengths. Increasing of SF content from 0.4% to 1.2% has significant improvement on NSC compressive and tensile strengths. PPF and GF addition caused decreasing on NSC compressive and tensile strengths.","PeriodicalId":14565,"journal":{"name":"IOSR Journal of Mechanical and Civil Engineering","volume":"10 1","pages":"27-34"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89628971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The article concerns the analysis of the impact of distributed heat storages (accumulators) type TES (Thermal Energy Storage) on the parameters of the district heating network. The simulation results show that the heat storage has a significant impact on the functioning quality of the heating system, reduces the time delay of transport and as well as minimizes heat loss during distribution process. The comparative analysis of simulation results and the data obtained from measurements confirmed the correctness of simulation studies.
本文分析了分布式蓄热(蓄能器)式TES (Thermal Energy Storage)对区域供热网络参数的影响。仿真结果表明，蓄热对供热系统的运行质量有显著的影响，减少了运输的时间延迟，最大限度地减少了分配过程中的热损失。仿真结果与实测数据的对比分析证实了仿真研究的正确性。
{"title":"Complete Analysis of the Impact of Distributed Heat Accumulators on the Efficiency of the District Heating Networks","authors":"Małgorzata Kwestarz","doi":"10.9790/1684-1403034349","DOIUrl":"https://doi.org/10.9790/1684-1403034349","url":null,"abstract":"The article concerns the analysis of the impact of distributed heat storages (accumulators) type TES (Thermal Energy Storage) on the parameters of the district heating network. The simulation results show that the heat storage has a significant impact on the functioning quality of the heating system, reduces the time delay of transport and as well as minimizes heat loss during distribution process. The comparative analysis of simulation results and the data obtained from measurements confirmed the correctness of simulation studies.","PeriodicalId":14565,"journal":{"name":"IOSR Journal of Mechanical and Civil Engineering","volume":"36 1","pages":"34-39"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75673374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Unconfined and Perched aquifers in irrigation command are more prone to water logging and salinity problems. Solution to these complexities using mathematical models does play around the source/sink term in majority and suggesting consumptive use as remedial measures becomes more often intentional. Elsewhere many researchers have found the problem caused by topography, clogging of pores and dissolution of nutrients/fertilizers. Numerical modeling of such processes requires adaptive techniques and software application. Such an adaptation is demonstrated in the present paper for the parts of the command area of right bank canal supplying water from Dharoi reservoir built on Sabarmati River in Gujarat state of India. HSI Geo Trans code SWIFT III has been used to generate purpose driven analyses. Results of the modeling analyses encouadoption of such improved technology.
{"title":"Model Application for salinity in Command Area.","authors":"Hemangini Parmar, Dr.N.D. Shah, P. Majumdar","doi":"10.9790/1684-1403010111","DOIUrl":"https://doi.org/10.9790/1684-1403010111","url":null,"abstract":"Unconfined and Perched aquifers in irrigation command are more prone to water logging and salinity problems. Solution to these complexities using mathematical models does play around the source/sink term in majority and suggesting consumptive use as remedial measures becomes more often intentional. Elsewhere many researchers have found the problem caused by topography, clogging of pores and dissolution of nutrients/fertilizers. Numerical modeling of such processes requires adaptive techniques and software application. Such an adaptation is demonstrated in the present paper for the parts of the command area of right bank canal supplying water from Dharoi reservoir built on Sabarmati River in Gujarat state of India. HSI Geo Trans code SWIFT III has been used to generate purpose driven analyses. Results of the modeling analyses encouadoption of such improved technology.","PeriodicalId":14565,"journal":{"name":"IOSR Journal of Mechanical and Civil Engineering","volume":"3 1","pages":"01-11"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81748002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Experimental studies of Ambient Cured Geopolymer Concrete","authors":"Xerses N. Irani","doi":"10.9790/1684-1403014449","DOIUrl":"https://doi.org/10.9790/1684-1403014449","url":null,"abstract":"","PeriodicalId":14565,"journal":{"name":"IOSR Journal of Mechanical and Civil Engineering","volume":"25 1","pages":"44-49"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82113786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Gaur, Jyotsana Jyotsana, Anil Arya, Neelesh Singh
Modern activities in India leads to use of plastic bags in excess. Plastic being non-biodegradable material, it takes years to decompose. Plastic bags have main constituent as poly-ethylene. The poly-ethylene when combusted produces a by-product of Carbon dioxide which leads to global warming.In this,we study the efficiency of reusing plastic waste in concrete by comparing compressive strength of concrete whose fine aggregate is partially replaced by plastic(5%,10%,15%,25%) with control concrete of M20 grade. To compensate for the strength lost due to replacement, iron fibres of diameter 1-2 mm are used in fixed amount.
{"title":"Use of Plastic as Partial Replacement of Fine Aggregate in Fibre Reinforced Concrete","authors":"K. Gaur, Jyotsana Jyotsana, Anil Arya, Neelesh Singh","doi":"10.9790/1684-1403037174","DOIUrl":"https://doi.org/10.9790/1684-1403037174","url":null,"abstract":"Modern activities in India leads to use of plastic bags in excess. Plastic being non-biodegradable material, it takes years to decompose. Plastic bags have main constituent as poly-ethylene. The poly-ethylene when combusted produces a by-product of Carbon dioxide which leads to global warming.In this,we study the efficiency of reusing plastic waste in concrete by comparing compressive strength of concrete whose fine aggregate is partially replaced by plastic(5%,10%,15%,25%) with control concrete of M20 grade. To compensate for the strength lost due to replacement, iron fibres of diameter 1-2 mm are used in fixed amount.","PeriodicalId":14565,"journal":{"name":"IOSR Journal of Mechanical and Civil Engineering","volume":"32 1","pages":"71-74"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85155793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The occurrence and characteristics by the configuration of the Process planning on the fabrication, which can have assignment comprising a broad range of activities to design and develop an appropriate fabrication process for producing a fragment. Interpretation of the part design, selection of fabrication processes, definition of operations, process sequences, machining datum’s, geometrical dimensions and tolerances are some common activities associated with the assignment. Process planning is also “the association between product design and fabrication” with the supplementary commission to upkeep design of competitive products. Process planning is of a complex and dynamic nature, often managed by a skilled person with uncommon or no explicit methods to solve the task. This paper has comprehensive aim of finding methods that cover essential activities for process planning, together with abilities to predict the outcome of a proposed fabrication process. This is recognized by gathering supporting methods appropriate to manage both qualitative and quantitative characterisation and analyses of a fabrication process
{"title":"Prediction of Process Planning By Reorganised Machining Operation Timing of LHB Bogie","authors":"L. Rajak, Novel Kumar Sahu","doi":"10.9790/1684-1402084046","DOIUrl":"https://doi.org/10.9790/1684-1402084046","url":null,"abstract":"The occurrence and characteristics by the configuration of the Process planning on the fabrication, which can have assignment comprising a broad range of activities to design and develop an appropriate fabrication process for producing a fragment. Interpretation of the part design, selection of fabrication processes, definition of operations, process sequences, machining datum’s, geometrical dimensions and tolerances are some common activities associated with the assignment. Process planning is also “the association between product design and fabrication” with the supplementary commission to upkeep design of competitive products. Process planning is of a complex and dynamic nature, often managed by a skilled person with uncommon or no explicit methods to solve the task. This paper has comprehensive aim of finding methods that cover essential activities for process planning, together with abilities to predict the outcome of a proposed fabrication process. This is recognized by gathering supporting methods appropriate to manage both qualitative and quantitative characterisation and analyses of a fabrication process","PeriodicalId":14565,"journal":{"name":"IOSR Journal of Mechanical and Civil Engineering","volume":"14 1","pages":"40-46"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89679521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Karimov J.A, Prof.Habibov I.A, Ass.Prof. Malikov R.Kh.
It is known that the strength and precision factors are the most important indicators of the quality for plastic parts. At the same time, the precision depends on the magnitude of shrinkage strain. Тherefore, it is possible to establish a direct analytical relationship between quality, strength and shrinkage strain factors, which is a function of the difference between the thermal stresses and other physical process. Currently, the difference in thermal stresses (residual stress) is not controlled due to the lack of reliable methods to determine and control their magnitude and direction. However, the magnitude of the volumetric or linear strain of finished products can be controlled by manipulating other quality factors.Determination of the link between volumetric strain and strength is possible by controlling the cooling process of the polymer components under normal operating conditions. Then it’s possible to analytically find the change in volumetric strain of the parts and the change in the difference of thermal stresses during cooling.Thus, the volumetric strain is a linear thermal shrinkage, i.e. the change of dimension and geometric shapes in all three directions (x, y, z) and is controlled by the quality criterion.On the other hand, the cooling process of plastic parts due to their low thermal conductivity is characterized by the cooling gradient of cross section. This leads to the formation of thermo-elastic stresses. The greater the temperature difference between the center and the surface layers, the more stress should be expected. For each infinitesimal layer the difference in the free thermal and total shrinkage rate will be compensated by a different strain.At first, the cooling rate of the outer layers despite the poor thermal conductivity greater than the internal. Further cooling results in a state where the cooling rate of the inner regions is greater than that of the outer. As a result, of this more intensive volume reduction begins in parts of the inner layers. The outer layers prevent this kind of decrease. The resistance of some layers of plastic parts to the shrinkage than that of the others causes thermal stresses, which at high temperatures can cause destruction of the components, if the value of any stress exceeds the tensile strength of the material.After cooling tangential compressive stresses are fixed in the outer layers of plastics and in the internal – tensile. Residual stresses are the greater, the greater the temperature difference over the cross section, the higher the rate of cooling and the lower part of the stresses succeed to relax, the greater are be residual stresses.Therefore, more detailed look shall be given to the distribution patterns of the thermal stresses drop for cylindrical plastic parts when they are cooled (fig.1).
众所周知，强度和精度因素是塑料件质量最重要的指标。同时，精度取决于收缩应变的大小。Тherefore，可以建立质量，强度和收缩应变因素之间的直接分析关系，这是热应力和其他物理过程之间差异的函数。目前，由于缺乏确定和控制其大小和方向的可靠方法，热应力(残余应力)的差异无法得到控制。然而，成品的体积或线性应变的大小可以通过操纵其他质量因素来控制。通过在正常操作条件下控制聚合物组分的冷却过程，可以确定体积应变和强度之间的联系。这样就可以解析出零件在冷却过程中体积应变的变化和热应力差的变化。因此，体积应变是线性热收缩，即尺寸和几何形状在所有三个方向(x, y, z)上的变化，并受质量标准控制。另一方面，由于塑料部件导热系数低，其冷却过程以截面的冷却梯度为特征。这导致热弹性应力的形成。中心层和表层之间的温差越大，预期的应力就越大。对于每一个无限小的层，自由热收缩率和总收缩率的差异将由不同的应变来补偿。首先，尽管外层导热性差，但其冷却速率大于内部。进一步冷却导致内部区域的冷却速率大于外部区域的冷却速率的状态。因此，这种更密集的体积缩小开始于内层的部分。外层防止了这种减少。某些层的塑料部件比其他层的塑料部件对收缩的抵抗力会引起热应力，如果任何应力的值超过材料的抗拉强度，热应力在高温下会导致部件的破坏。冷却后切向压应力固定在塑料的外层和内部的拉伸层。残余应力越大，截面温差越大，冷却速度越快，应力松弛的下部越大，残余应力越大。因此，对于圆柱形塑料件冷却时的热应力降分布规律(图1)应给予更详细的观察。
{"title":"Mathematical Description Design Process of Plastic Details","authors":"Karimov J.A, Prof.Habibov I.A, Ass.Prof. Malikov R.Kh.","doi":"10.9790/1684-1403050103","DOIUrl":"https://doi.org/10.9790/1684-1403050103","url":null,"abstract":"It is known that the strength and precision factors are the most important indicators of the quality for plastic parts. At the same time, the precision depends on the magnitude of shrinkage strain. Тherefore, it is possible to establish a direct analytical relationship between quality, strength and shrinkage strain factors, which is a function of the difference between the thermal stresses and other physical process. Currently, the difference in thermal stresses (residual stress) is not controlled due to the lack of reliable methods to determine and control their magnitude and direction. However, the magnitude of the volumetric or linear strain of finished products can be controlled by manipulating other quality factors.Determination of the link between volumetric strain and strength is possible by controlling the cooling process of the polymer components under normal operating conditions. Then it’s possible to analytically find the change in volumetric strain of the parts and the change in the difference of thermal stresses during cooling.Thus, the volumetric strain is a linear thermal shrinkage, i.e. the change of dimension and geometric shapes in all three directions (x, y, z) and is controlled by the quality criterion.On the other hand, the cooling process of plastic parts due to their low thermal conductivity is characterized by the cooling gradient of cross section. This leads to the formation of thermo-elastic stresses. The greater the temperature difference between the center and the surface layers, the more stress should be expected. For each infinitesimal layer the difference in the free thermal and total shrinkage rate will be compensated by a different strain.At first, the cooling rate of the outer layers despite the poor thermal conductivity greater than the internal. Further cooling results in a state where the cooling rate of the inner regions is greater than that of the outer. As a result, of this more intensive volume reduction begins in parts of the inner layers. The outer layers prevent this kind of decrease. The resistance of some layers of plastic parts to the shrinkage than that of the others causes thermal stresses, which at high temperatures can cause destruction of the components, if the value of any stress exceeds the tensile strength of the material.After cooling tangential compressive stresses are fixed in the outer layers of plastics and in the internal – tensile. Residual stresses are the greater, the greater the temperature difference over the cross section, the higher the rate of cooling and the lower part of the stresses succeed to relax, the greater are be residual stresses.Therefore, more detailed look shall be given to the distribution patterns of the thermal stresses drop for cylindrical plastic parts when they are cooled (fig.1).","PeriodicalId":14565,"journal":{"name":"IOSR Journal of Mechanical and Civil Engineering","volume":"2 1","pages":"01-03"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90389461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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