The work deals with the application of Cad active parametric/variational model in the mechanisms’ modeling in “physically based design” field of research. The term “active Cad model” means a parametric/variational Cad model, geometric one, whose dimensions can vary according to the Physical laws, that describe their original mechanical behavior. For example, if the specimen is subjected to a traction stress and a moving law is imposed to one of its ends, it must not only be able to stretch indefinitely, but it will have to show the same physical phenomena happening in the real test (elastic extension, strain and plasticization till the break point). Such model can be obtained imposing the characteristics of the material to the model under the feature of CAD’s parameters, that will be used to refresh dimensions and shape of the own model. Modern CAD systems offer to users several programming tools that can be used to manage the model. In particular it is possible to impose on a model a whole series of geometrical and dimensional constraints, that allow us to manage the shape, modifying the parameters’ values. Such constraints are managed through functions opportunely defined. In the active model, the function depends also on the parameters representing the mechanical characteristic of the simulated materials. The aim of this work is to show the use and the versatility of the active models in different applications. It has been realized an active model of a cylindrical spring and it has been applied in two mechanisms, different for typology and for backlash loads. The first example is a dynamometer in which the cylindrical spring is loaded by traction forces, while the second example is made up from a pressure valve in which the cylindrical-conic spring works under compression. The imposition of the loads in both cases, has allowed us to evaluate the model of the mechanism in different working conditions, also in assembly environment.
CAD ACTIVE MODELS: AN INNOVATIVE METHOD IN ASSEMBLY ENVIRONMENT.
NADDEO, ALESSANDRO;CAPPETTI, Nicola;PAPPALARDO, Michele
2010-01-01
Abstract
The work deals with the application of Cad active parametric/variational model in the mechanisms’ modeling in “physically based design” field of research. The term “active Cad model” means a parametric/variational Cad model, geometric one, whose dimensions can vary according to the Physical laws, that describe their original mechanical behavior. For example, if the specimen is subjected to a traction stress and a moving law is imposed to one of its ends, it must not only be able to stretch indefinitely, but it will have to show the same physical phenomena happening in the real test (elastic extension, strain and plasticization till the break point). Such model can be obtained imposing the characteristics of the material to the model under the feature of CAD’s parameters, that will be used to refresh dimensions and shape of the own model. Modern CAD systems offer to users several programming tools that can be used to manage the model. In particular it is possible to impose on a model a whole series of geometrical and dimensional constraints, that allow us to manage the shape, modifying the parameters’ values. Such constraints are managed through functions opportunely defined. In the active model, the function depends also on the parameters representing the mechanical characteristic of the simulated materials. The aim of this work is to show the use and the versatility of the active models in different applications. It has been realized an active model of a cylindrical spring and it has been applied in two mechanisms, different for typology and for backlash loads. The first example is a dynamometer in which the cylindrical spring is loaded by traction forces, while the second example is made up from a pressure valve in which the cylindrical-conic spring works under compression. The imposition of the loads in both cases, has allowed us to evaluate the model of the mechanism in different working conditions, also in assembly environment.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
