Project 1
Aim : Meshing and Mid-surfacing of Dashboard using ANSA pre-processor.
Objectives :
For the given component (Dashboard), checking for the geometrical errors and meshing with the given element Quality criteria. After meshing the component the thickness has to be assigned.
1) To clean up the topological errors.
2) To clean the geometry using different set of tools.
3) Running diagnostic check.
4) Use of Boolean operations for better visuality of the geometry.
5) Create mid-surface depending on the type of geometry.
5) Assigning length and meshing the whole geometry.
6) Compressing the geometry after rectifying all the errors in it.
Introduction :
A dashboard (also called dash, instrument panel (IP) is a control panel usually located directly ahead of a vehicle's driver, displaying instrumentation and controls for the vehicle's operation. Where the dashboard originally included an array of simple controls (e.g., the steering wheel) and instrumentation to show speed, fuel level and oil pressure, the modern dashboard may accommodate a broad array of gauges, and controls as well as information, climate control and entertainment systems. Contemporary dashboards may include the speedometer, tachometer, odometer, engine coolant temperature gauge, and fuel gauge, turn indicators, gearshift position indicator, seat belt warning light, parking-brake warning light, and engine-malfunction lights. Other features may include a gauge for alternator voltage, indicators for low fuel, low oil pressure, low tire pressure and faults in the airbag (SRS) systems, glove compartment, ashtray and a cigarette lighter or power outlet as well as heating and ventilation systems, lighting controls, safety systems, entertainment equipment and information systems e.g., navigation systems.
Dashboards are generally made of polyvinyl chloride, invented in the early 1920s and now used in everything from water pipes to shower curtains. PVC can be rock hard or cloth flexible. ABS plastic (Acrylonitrile Butadiene Styrene) Steering wheel covers and dashboards are often made of ABS plastic. It's also well-suited to heavy-duty applications, so it can be used for automotive body parts, too.
Features in dashboard is given as follows :
Quality Criteria :
Mesh parameters :
Procedure :
1) Basic procedure follows with cleaning up the geometry by identifying the geometrical errors listed under the check manager such as single cons, triple cons, unchecked faces, Collapsed cons, Needle faces, Overlap faces, Cracks and penetration errors which should be avoided to proceed further, if we clean up most of the geometry there will be least possibility in error while meshing.
Most of the Errors can be fixed by using Auto Fix option in the check manager menu others can be fixed by manually.
2) For manual fixation of errors in the geometry, there are several approach we can use. Topo tool can be used to paste all the single cons (Red cons) in the geometry into double cons (Yellow color). But in some cases there is extra entity in between which causes the operation to turn it into triple cons (Cyan color). In this case we can follow the procedure below
Release tool under CONs in the TOPO module is used to release the surrounding selected cons so we're able to delete the extra face in CAD geometry.
We found that the error face deleted was not enough to fix the issue so we delete the entity beside it to close the surface geometry. To create a new face we use New options in FACES and select the Face type, in this case we have chose FITTED option which was perfect fit for this type face.
In the below picture we can see that the face is fixed
3) Now, again we run check manager and look for any error, we there is no error than we can proceed onto the further step.
4) Measuring thickness of all the parts in the geometry for Mid-surfacing and thickness assignment
Measuring the thickness of the base frame of the dashboard
Measuring the ribs and fixtures on the base frame of the dashboard. Here we can see that there is varying thickness in the geometry for ribs and fixture attached to base.
4) Mid-surface is extracted using offset method. Mid-surfacing depends on the type of geometry, if the thickness is varying across the geometry then manual mid-surface extraction method should be used. For example for the picture shown below the thickness of that particular part is 0.6mm, we achieve this using measuring tool to get the distance from node to node. Now using offset method for mid surface extraction we can use feature angle option by defining an angle to certain extent for which it can select the faces upto given that angle. After this, selecting the surfaces by giving the offset value, since we want middle surface it is written in half of the measured value which is -0.6/2mm and negative sign because the vector is in opposite direction to that of the surface.
5) For some faces we can use middle option for mid-surfacing such as ribs. We need not measure the thickness of a particular part, by just selecting the surfaces it will extract the mid surface. This option is only useful when the two surfaces are of same shape or identical surface on each side.
6) Extend tool under 'Faces' option in the 'TOPO' module is used to connect the the single midsurface parts which are left hanging are pasted to the base geometry to achieve proper midsurface of the whole geometry. First selecting the cons followed by middle click mouse confirmation than select the surface on which the cons should be extended.
7) After Mid surfacing all the part in the geometry, the mid-plane geometry is checked for any errors in the check manager, as we can see below.
When all the errors are fixed in the mid plane we can proceed to next step
8) After extracting mid surface for each part, we have to assign thickness in the Property id menu where different properties can be assigned to that particular part. Here, since we have varying thickness throughout the geometry, thickness will be different for each part. Thickness is given as 'T' in the Properties menu.
Thus setting up Pids for rest of the parts as shown in the below picture :
9) Meshing of the geometry is done by using 'Batch' mesh option under 'Mesh Generation'. What Batch mesh option does is, the geometry to be mesh is first feeded in the meshing scenario, the information given in the mesh parameters and the quality criteria to give the best possible results which are significant to the meshing of geometry.
Running the batch mesh option, the time take by Batch Mesh Manager to generate depends on element length and the type of element used.
10) The desired mesh quality is achieved by elminating the OFF elements which do not fit under the quality criteria.
We can see that, there are still some OFF elements which batch mesh couldn't fix even after feeding the quality criteria and mesh parameters; therefore we have to identify and fix them manually.
Using Swap and Split tools for fixing the errors or some times combination of both under Elements in the MESH module. Uncut option can be used but the actual mesh mid-plane geometry should not be affected by it.
Automatic options also can be used such as Reconstruction, Smoothening, Fix Quality, Shape etc. In this case we have used Fix Quality tool to get rid of the OFF elements in the present geometry.
11) After getting rid of all OFF elements, 'Draw shell as solid elements' in the Presentation parameter enables to view the thickness which we assigned for the whole geometry.
Conclusion :
Successful completion of the given geometry was done step by step. Mid-surfacing of critical parts in the sub system as well as satisfying the given mesh parameters and quality criteria was achieved