In order to study the viscoelastic characteristics of asphalt mixtures in the whole-frequency range, a dynamic shearing rheometer is used to carry out dynamic frequency sweeps for asphalt mixtures, which obtains the t...In order to study the viscoelastic characteristics of asphalt mixtures in the whole-frequency range, a dynamic shearing rheometer is used to carry out dynamic frequency sweeps for asphalt mixtures, which obtains the three-dimensional relationships among G^＊, temperature and frequency. Then the time-temperature shift principle is used to translate the relationships from three dimensions to two dimensions, so master curves are obtained regarding dynamic modules changing along with the frequency over 15 amount levels. The Christensen- Anderson-Marasteanu （CAM） model, a kind of the rheological model, is used to analyze and compare rheological performances of several asphalt mixtures based on the obtained master curves. The results indicate that the dynamic theological test is an effective method for obtaining the master curve. Besides, the CAM model can describe well the viscoelastic deformation characteristics of asphalt mixtures.展开更多
The globalization and the intensive competition of th e automotive market require shortening the product development cycle, improving the quality and reducing the cost. Optimizing the product development process, b ui...The globalization and the intensive competition of th e automotive market require shortening the product development cycle, improving the quality and reducing the cost. Optimizing the product development process, b uilding product’s consistent defining model for life cycle, and realizing the in tegration of CAD/CAM/CAE and Concurrent Engineering (CE) become the means to acc ept the challenge. A new product modeling technology, Multi Model Technology (MM T), is provided in this paper to meet the needs of the challenge for automotive powertrain product development. First, the paper introduces the concept of Multi Model Technology. MMT introduce s Object-oriented Technology (OT) into product modeling process and combine OT with feature-based modeling technology. With the help of OT, MMT builds product object model to support system level management in product development. The obj ect model of the product is a Multi Model Structure. The MMS consists of finish part model level (assembly model level), rough part model level (part model leve l), function model level and basic model level. Every models in the MMS is creat ed by feature-based technology in design process. In this case, models in the M MS of product can be shared by casting mould, sand core and sand core mould. The refore, CAD engineers, CAE engineers and CAM engineers can work concurrently and the integration of CAD/CAM/CAE can be realized. Second, MMT is applied in cylinder head development. The multi model structures of cylinder head, its casting mould, sand core and sand core mould are built, an d the process-oriented feature models of every objects in the multi model struc tures are modeled, the application of different model objects in development pro cess is analyzed. The integrated modeling technology of cylinder head, its casti ng mould, sand core and sand core mould under MMT is studied. And the concurrent engineering oriented integration method of CAD/CAE and the method to realize th e integration of CAD/CAE under MMT are also discussed. Based on above, the integ ration of CAD/CAM/CAE of cylinder head is realized in automotive powertrain prod uct. The practice results shows that the modeling technology in this paper can optimi ze the development process, realize the data sharing and concurrent engineering in the product development process.展开更多
针对金刚石滚轮是一种回转体零件以及其加工制造过程中信息化集成程度低等特点,对金刚石滚轮的特征信息提取、特征加工方案决策、数控程序后置处理等关键技术进行了研究,采用了产品模型数据交换标准STEP AP 242,实现对金刚石滚轮的制造...针对金刚石滚轮是一种回转体零件以及其加工制造过程中信息化集成程度低等特点,对金刚石滚轮的特征信息提取、特征加工方案决策、数控程序后置处理等关键技术进行了研究,采用了产品模型数据交换标准STEP AP 242,实现对金刚石滚轮的制造特征信息提取,使用STEP AP 242和PDM相结合的集成方式,将金刚石滚轮三维模型作为制造加工信息的载体,并选择SolidWorks作为CAD和CAM软件,以及选择Aras Innovator作为PDM平台,使用C#编程语言和数据库技术开发了金刚石滚轮CAD/CAPP/CAM/PDM集成系统,并进行了实例验证。展开更多
Considering grinding a cam with numerical control（NC）cam grinder,a mathematical model should be estab- lished with the unified parameter based on the original cam-lobe lift data to describe the movement of wheel and...Considering grinding a cam with numerical control（NC）cam grinder,a mathematical model should be estab- lished with the unified parameter based on the original cam-lobe lift data to describe the movement of wheel and establish the relation between the wheel center coordinate,the measuring angle and workpiece’s spindle rotation angle.By analyzing,the grinding wheel can be regarded as different followers.To the planar and roller followers,different mathematical models are established, but they can be unified in Eqs.（17）of this paper with the different value of the roller radius r<sub>1</sub>.And also the model is suit for the edged follower when assuming the roller radius r<sub>1</sub>=0.Experimental verification was done with TKM120 CNC/CBN grinder with NC sets’ interpolation according to the model,which shows that high precision parts can be manufactured and this mathemat- ical model can be practically applied for NC cam grinder.展开更多
How CAD design and simulation tools can assist in developing vacuum circuit breaker （VCB） in general is demonstrated. The electric field calculation has been widely utilized for electrical insulation design of VCB. ...How CAD design and simulation tools can assist in developing vacuum circuit breaker （VCB） in general is demonstrated. The electric field calculation has been widely utilized for electrical insulation design of VCB. ADAMS is applied in dynamic simulation to fulfill the complex calculation of mechanical characteristics. Satisfactory simulation results can be obtained by iteratively refining parameters of the model, and it is shown that this scheme can be used to provide a good basis for optimum design of VCB.展开更多
【目的】采用CAD/CAM标准测试模型评价四种不同临时冠粘结剂的粘结强度。【方法】参照因牙周病拔除的完整上颌中切牙CAD/CAM40副上颌中切牙的树脂测试模型(包括预备体和带固位孔的临时冠),分为4组(氧化锌组、玻璃离子体水门汀组、磷酸...【目的】采用CAD/CAM标准测试模型评价四种不同临时冠粘结剂的粘结强度。【方法】参照因牙周病拔除的完整上颌中切牙CAD/CAM40副上颌中切牙的树脂测试模型(包括预备体和带固位孔的临时冠),分为4组(氧化锌组、玻璃离子体水门汀组、磷酸锌水门汀组和Tempo Cem NE组),每组10副模型,每组分别采用4种不同的临时冠粘结剂进行粘结。采用MTS力学测试机对每一副模型以1mm/min的速度进行粘结强度测试,测出并记录每组每一副模型的粘结强度。【结果】4组的粘结强度分别为氧化锌组(37.48±4.92)N、玻璃离子体水门汀组(52.13±9.28)N、磷酸锌水门汀组(36.16±6.13)N、Tempo Cem NE组(46.21±6.70)N;玻璃离子体水门汀组和Tempo Cem NE组的粘结强度大于氧化锌组和磷酸锌水门汀组,差异具有统计学意义(P<0.05)。【结论】采用CAD/CAM上颌中切牙的标准测试模型进行4种临时冠粘结剂粘结强度的测试,实验结果认为玻璃离子体水门汀和Tempo Cem NE的粘结效果较好,值得临床广泛应用。展开更多
基金The National Natural Science Foundation of China (No.50278037)
文摘In order to study the viscoelastic characteristics of asphalt mixtures in the whole-frequency range, a dynamic shearing rheometer is used to carry out dynamic frequency sweeps for asphalt mixtures, which obtains the three-dimensional relationships among G^＊, temperature and frequency. Then the time-temperature shift principle is used to translate the relationships from three dimensions to two dimensions, so master curves are obtained regarding dynamic modules changing along with the frequency over 15 amount levels. The Christensen- Anderson-Marasteanu （CAM） model, a kind of the rheological model, is used to analyze and compare rheological performances of several asphalt mixtures based on the obtained master curves. The results indicate that the dynamic theological test is an effective method for obtaining the master curve. Besides, the CAM model can describe well the viscoelastic deformation characteristics of asphalt mixtures.
文摘The globalization and the intensive competition of th e automotive market require shortening the product development cycle, improving the quality and reducing the cost. Optimizing the product development process, b uilding product’s consistent defining model for life cycle, and realizing the in tegration of CAD/CAM/CAE and Concurrent Engineering (CE) become the means to acc ept the challenge. A new product modeling technology, Multi Model Technology (MM T), is provided in this paper to meet the needs of the challenge for automotive powertrain product development. First, the paper introduces the concept of Multi Model Technology. MMT introduce s Object-oriented Technology (OT) into product modeling process and combine OT with feature-based modeling technology. With the help of OT, MMT builds product object model to support system level management in product development. The obj ect model of the product is a Multi Model Structure. The MMS consists of finish part model level (assembly model level), rough part model level (part model leve l), function model level and basic model level. Every models in the MMS is creat ed by feature-based technology in design process. In this case, models in the M MS of product can be shared by casting mould, sand core and sand core mould. The refore, CAD engineers, CAE engineers and CAM engineers can work concurrently and the integration of CAD/CAM/CAE can be realized. Second, MMT is applied in cylinder head development. The multi model structures of cylinder head, its casting mould, sand core and sand core mould are built, an d the process-oriented feature models of every objects in the multi model struc tures are modeled, the application of different model objects in development pro cess is analyzed. The integrated modeling technology of cylinder head, its casti ng mould, sand core and sand core mould under MMT is studied. And the concurrent engineering oriented integration method of CAD/CAE and the method to realize th e integration of CAD/CAE under MMT are also discussed. Based on above, the integ ration of CAD/CAM/CAE of cylinder head is realized in automotive powertrain prod uct. The practice results shows that the modeling technology in this paper can optimi ze the development process, realize the data sharing and concurrent engineering in the product development process.
文摘针对金刚石滚轮是一种回转体零件以及其加工制造过程中信息化集成程度低等特点,对金刚石滚轮的特征信息提取、特征加工方案决策、数控程序后置处理等关键技术进行了研究,采用了产品模型数据交换标准STEP AP 242,实现对金刚石滚轮的制造特征信息提取,使用STEP AP 242和PDM相结合的集成方式,将金刚石滚轮三维模型作为制造加工信息的载体,并选择SolidWorks作为CAD和CAM软件,以及选择Aras Innovator作为PDM平台,使用C#编程语言和数据库技术开发了金刚石滚轮CAD/CAPP/CAM/PDM集成系统,并进行了实例验证。
文摘Considering grinding a cam with numerical control（NC）cam grinder,a mathematical model should be estab- lished with the unified parameter based on the original cam-lobe lift data to describe the movement of wheel and establish the relation between the wheel center coordinate,the measuring angle and workpiece’s spindle rotation angle.By analyzing,the grinding wheel can be regarded as different followers.To the planar and roller followers,different mathematical models are established, but they can be unified in Eqs.（17）of this paper with the different value of the roller radius r<sub>1</sub>.And also the model is suit for the edged follower when assuming the roller radius r<sub>1</sub>=0.Experimental verification was done with TKM120 CNC/CBN grinder with NC sets’ interpolation according to the model,which shows that high precision parts can be manufactured and this mathemat- ical model can be practically applied for NC cam grinder.
文摘How CAD design and simulation tools can assist in developing vacuum circuit breaker （VCB） in general is demonstrated. The electric field calculation has been widely utilized for electrical insulation design of VCB. ADAMS is applied in dynamic simulation to fulfill the complex calculation of mechanical characteristics. Satisfactory simulation results can be obtained by iteratively refining parameters of the model, and it is shown that this scheme can be used to provide a good basis for optimum design of VCB.
文摘【目的】采用CAD/CAM标准测试模型评价四种不同临时冠粘结剂的粘结强度。【方法】参照因牙周病拔除的完整上颌中切牙CAD/CAM40副上颌中切牙的树脂测试模型(包括预备体和带固位孔的临时冠),分为4组(氧化锌组、玻璃离子体水门汀组、磷酸锌水门汀组和Tempo Cem NE组),每组10副模型,每组分别采用4种不同的临时冠粘结剂进行粘结。采用MTS力学测试机对每一副模型以1mm/min的速度进行粘结强度测试,测出并记录每组每一副模型的粘结强度。【结果】4组的粘结强度分别为氧化锌组(37.48±4.92)N、玻璃离子体水门汀组(52.13±9.28)N、磷酸锌水门汀组(36.16±6.13)N、Tempo Cem NE组(46.21±6.70)N;玻璃离子体水门汀组和Tempo Cem NE组的粘结强度大于氧化锌组和磷酸锌水门汀组,差异具有统计学意义(P<0.05)。【结论】采用CAD/CAM上颌中切牙的标准测试模型进行4种临时冠粘结剂粘结强度的测试,实验结果认为玻璃离子体水门汀和Tempo Cem NE的粘结效果较好,值得临床广泛应用。
