**7. Application of CAE systems**

The Computer Aided Engineering (CAE) systems were developed to simulate real applications, and enabling auxiliary steps of projects and manufacturing. There exists CAE

Advanced Free Form Manufacturing by Computer Aided Systems – Cax 585

(a) (b)

temperature, among other information that composed the simulation.

injection of the product, and the pressure of injection.

Fig. 27. Simulation results of the injection process

efficiency of each proposal.

**8. Application of CAI systems** 

and non-equilateral triangles; open mesh

Fig. 26. Finite elements mesh with problems. a) Product CAD; b) Mesh. Plans not oriented

In cases of problems in the automatic construction of the finite elements mesh, the user should interact with the software in order to provide an adequate mesh. The dimensions of the elements that compose the mesh can be defined by the user and will have repercussions in the precision of the calculation. Still in the pre-processing, all the conditions of contour should be supplied, such as: mechanical stresses, strength of the product material,

The results, in general, are presented in the form of multicoloured graphics, according to the analysis requested. Figure 27 illustrates the result of the simulation of the injection of a plastic product, having like variables in the temperature injection necessary, the time of

(a) Temperature (b) Cycle time (c) Pressure of injection

In this case it is also possible to simulate the cooling systems of the mould and the degree of

The Computer-Aided Inspection (CAI) represents the final integration of manufacturing processes, this step is performed as a comparison between the geometric model constructed in the CAD, which represents the theoretical form of the design geometry without dimensional errors, with the product manufactured, which has so errors arising from

mechanical limitations of both machine tool and manufacturing process.

software specifically for each application. The software SigmaSoft® and Moldflow® are examples of CAE to simulate the transformation of plastic and none metallic products. The software Ansys® and Nastran® are more specific for simulations of mechanical demands dynamic statistics.

Simulations of products and processes have been highly desired for the last decade for various applications. Secure results of these simulations can prevent accidents, reduce manufacturing costs, optimise products behind for example the reduction of the thickness, how to help in the substitution of materials, collecting materials, and making processes and products more efficient.

The CAE systems make sophisticated mathematical algorithms to perform calculations. The quality of a simulation involves a degree of approximation between the results obtained and the real situation. This relation of the mathematical algorithm employed for the generation of the finite elements mesh and for the calculations asked for. This way the information entered, such as the geometry, mechanical demands and materials.

Information about the process to be simulated must be attributed to the CAE system to make the calculations. This information is called entrance variables. Both variables are specifically defined in function of the process and/or the product studied.

To carry out the simulation calculations, CAE uses finite technical elements. The geometry originating from CAD can be used to analyse the primitive elements, such as triangles. Therefore the software generates a geometry dominated by a finite elements mesh, which represents an object or a process to be simulated. Finite elements and methods are widely employed by CAE systems.

The working procedures to carry out simulations with CAE systems can be divided in three main phases: pre-processing (generation of the sweater of finite elements and variables of entrance), processing (calculation of the demands) and post-processing (evaluation and interpretation of the answer of the software), approached with more property in the sequence.

In the pre-processing the modelling of the product is supplied by the CAD system. In case it cannot be integrated with the systems CAD/CAE, the geometry should be exported by the CAD through a standard interface (IGES, by example) and imported in the CAE system. After importing the geometry, the CAE system should calculate the finite elements mesh. This is a crucial step for the quality of simulation, because the nodes of the finite elements mesh are used as the basis for all calculations performed in CAE applications.

The quality of the finite elements mesh generated by the software is attributed mainly by the homogeneity of the elements that it composes. The best condition will be generated by software that contains the largest number of elements and dimensions equilateral homogeneous. The mesh calculated by the software can at times be unstable, having repercussions in future simulations. In these cases the user should be qualified to identify and correct such limitations of software, which can be related with the complexity of the surface, rank of refinement of the mesh, quality of the surface imported of the CAD via communication patterns, beyond the mathematical limitations made for generation of the mesh. Figure 26 (a) illustrates the CAD model, (b) example of mesh with none equilateral regions containing elements and a fault of connection between the elements, which represents errors or impossibilities of calculation.

software specifically for each application. The software SigmaSoft® and Moldflow® are examples of CAE to simulate the transformation of plastic and none metallic products. The software Ansys® and Nastran® are more specific for simulations of mechanical demands

Simulations of products and processes have been highly desired for the last decade for various applications. Secure results of these simulations can prevent accidents, reduce manufacturing costs, optimise products behind for example the reduction of the thickness, how to help in the substitution of materials, collecting materials, and making processes and

The CAE systems make sophisticated mathematical algorithms to perform calculations. The quality of a simulation involves a degree of approximation between the results obtained and the real situation. This relation of the mathematical algorithm employed for the generation of the finite elements mesh and for the calculations asked for. This way the information

Information about the process to be simulated must be attributed to the CAE system to make the calculations. This information is called entrance variables. Both variables are

To carry out the simulation calculations, CAE uses finite technical elements. The geometry originating from CAD can be used to analyse the primitive elements, such as triangles. Therefore the software generates a geometry dominated by a finite elements mesh, which represents an object or a process to be simulated. Finite elements and methods are widely

The working procedures to carry out simulations with CAE systems can be divided in three main phases: pre-processing (generation of the sweater of finite elements and variables of entrance), processing (calculation of the demands) and post-processing (evaluation and interpretation of the answer of the software), approached with more property in the

In the pre-processing the modelling of the product is supplied by the CAD system. In case it cannot be integrated with the systems CAD/CAE, the geometry should be exported by the CAD through a standard interface (IGES, by example) and imported in the CAE system. After importing the geometry, the CAE system should calculate the finite elements mesh. This is a crucial step for the quality of simulation, because the nodes of the finite elements

The quality of the finite elements mesh generated by the software is attributed mainly by the homogeneity of the elements that it composes. The best condition will be generated by software that contains the largest number of elements and dimensions equilateral homogeneous. The mesh calculated by the software can at times be unstable, having repercussions in future simulations. In these cases the user should be qualified to identify and correct such limitations of software, which can be related with the complexity of the surface, rank of refinement of the mesh, quality of the surface imported of the CAD via communication patterns, beyond the mathematical limitations made for generation of the mesh. Figure 26 (a) illustrates the CAD model, (b) example of mesh with none equilateral regions containing elements and a fault of connection between the elements, which

mesh are used as the basis for all calculations performed in CAE applications.

represents errors or impossibilities of calculation.

entered, such as the geometry, mechanical demands and materials.

specifically defined in function of the process and/or the product studied.

dynamic statistics.

products more efficient.

employed by CAE systems.

sequence.

Fig. 26. Finite elements mesh with problems. a) Product CAD; b) Mesh. Plans not oriented and non-equilateral triangles; open mesh

In cases of problems in the automatic construction of the finite elements mesh, the user should interact with the software in order to provide an adequate mesh. The dimensions of the elements that compose the mesh can be defined by the user and will have repercussions in the precision of the calculation. Still in the pre-processing, all the conditions of contour should be supplied, such as: mechanical stresses, strength of the product material, temperature, among other information that composed the simulation.

The results, in general, are presented in the form of multicoloured graphics, according to the analysis requested. Figure 27 illustrates the result of the simulation of the injection of a plastic product, having like variables in the temperature injection necessary, the time of injection of the product, and the pressure of injection.

Fig. 27. Simulation results of the injection process

In this case it is also possible to simulate the cooling systems of the mould and the degree of efficiency of each proposal.

#### **8. Application of CAI systems**

The Computer-Aided Inspection (CAI) represents the final integration of manufacturing processes, this step is performed as a comparison between the geometric model constructed in the CAD, which represents the theoretical form of the design geometry without dimensional errors, with the product manufactured, which has so errors arising from mechanical limitations of both machine tool and manufacturing process.

**Part 5** 

**New Approaches for Mechanical Engineering** 

**Education and Organization Systems** 

At this stage, the CAI software receives the geometric information of CAD and information representing the final product, obtained by a coordinate measuring machine, through a cloud of points. CAI compares the geometric errors between the real object with the CAD design and report on the regions with the geometrical deviations, considering the tolerances specified in the project (Figure 28).

Fig. 28. Integration of CAD/CAI/MMC
