Graphics Systems SolidNotes

VALVE DESIGN AND TORQUE CALCULATIONS USING SOLIDWORKS FLOW SIMULATION

In this article, we are going to determine Dynamic Torque generated by Water at various position of the Valve. The given value geometry is checked in SolidWorks and previewed using SolidWorks Flow Simulation "Check Geometry Options". There were no penetration/interferences in this simplified model.

Flow  Analysis - Operating Conditions:

Pressure and Velocity Plots at 23 degree open Condition:

Pressure and Velocity Plots at 67 degree open Condition:

Pressure and Velocity at Full open Condition:

 

 

 Summary of Results:

SolidWorks Configuration	Y-Component of Torque (lbf-in)	Comments
23 degree open	58254.36127	Total cells=346747, Results converged
67 degree open	3844.252027	Total cells=261074, Results converged
Full open	-0.699287861	Total cells=274276, Results converged

Conclusions & Advantages of using SolidWorks Flow Simulation :

• The single design environment of SolidWorks enables users to set-up simulations quicker, and easily correlate design changes with analysis results.
• SolidWorks has simplified the entire analysis workflow. With SolidWorks’ streamlined interface, Flow Wizard, and in-depth help, novice users are able to set up complex Analysis studies and easily interpret the results.
• Meshing is a far simpler automated process for upfront design. If the prospect has complex geometry, SolidWorks Flow will prove far more reliable in creating the mesh.
• SolidWorks Flow Simulation yields highly accurate results. SolidWorks Flow also has state of the    art technology for modeling turbulence and thin wall geometry.
   
  

MOTION..........LIKE NEVER BEFORE !!

My previous article did give you some insights about importing motion loads in Simulation 2009. Time and again solidworks Simulation has proved that its trying to make our life easy every year with new enhancements. In 2010, it has now added the Simulation Setup inside motion. Once you are all set with your required mechanism in Motion, all you need to do is go to the Simulation Setup and it will guide you through the process. You can specify the mesh density, time steps and material property during the simulation setup process.

As we click on “Calculate” to compute for our motion study, we need to go with “Calculate Simulation Study” and then obtain Stress, Factor of Safety and Displacement plots. The cool feature is that as you would visualize any normal motion study, you can also view the  Simulation plots changing in real time. It again depends on the time step that you specify during the Simulation Setup within the Motion Study.

All the above mentioned was motion analysis with respect to time.  Solidworks Simulation team has also come up with “Event based Motion” as a part of Simulation Professional in 2010 version. This could be easily explained from the fact that one event triggers another event in a sequence. This type of motion analysis is very important when we are unaware of any time factors in the motion study.

WHERE IS MY PART ? …………….I NEED MOTION LOADS

As the title describes, you may have often come across a situation where you need to import the motion loads on any one of the component/part and the moment you click on simulation-Import motion loads, you do not see any part mentioned in the “Available Assembly Components”.  This might lead you to think whether – did the motion study go through? or is it a bug in the software ? Well the answer is simple. In Simulation, you have to make sure that the components of interest has to be a single part i.e. child of the main assembly rather than being a part of a sub assembly. Any part  belonging to a subassembly will not show up in the available components list. In Simulation motion, where you have to often deal with mates, redundancies and so on, it is always better to think about the parts of interest in the beginning cause this might lead you to spend long hours in re-creating the mates while trying to dissolve the subassembly.

 

There is another work around for the above problem. This can be done by using the command “Dissolve sub assembly”. All you need to do is right click on the sub-assembly and select “Dissolve sub assembly”. This will help you to break the parts under the sub-assembly and make them the children of the main assembly. Again, as mentioned earlier, care has to be taken before proceeding with the motion study as this might leave you with all of errors in mates.

I hope, this will give you a heads up on how to proceed with a motion study and save you some time and focus more on simulation (motion and FEA) rather than re-creating the assembly mates.

It's time for "FEA - CREEP Analysis using SOLIDWORKS SIMULATION"

What is Creep?

Creep is a time varying, permanent strain due to long term application of constant or near constant stress level. Creep is observed in most engineering materials especially metals at elevated temperatures, high polymer plastics, concrete, and solid propellant in rocket motors.

Creep Analyses require detailed materail data that are dependent on duration of load and the magnitude of initial stress and temperature. Creep is not a significant concern for most metals until operating temperature reach 35% to70% of respective melting points.

Creep Curve:

Creep curve is a graph between strain versus time. Three different regimes can be distinguished in a creep curve; primary, secondary, and tertiary (see the following figure). Usually primary and secondary regimes are of interest.

 

Follow Simple and Easy Steps to Simulate Creep Study in SolidWorks Simulation:

Step_1: Define Nonlinear as a type of study 

Step_2: Define the materail properties with Creep effects

 

Step_3: Define Operating Conditions - Loads/Restraints and Mehsing 

Step_4: Properties set up, Run & Post Process the results 

 

  

Conclusion:

Based on this creep analysis study using SolidWorks Simulation (Premium Module), the model set up, meshing and analysis run was done very quickly. The challenge was to get the Creep constants for the materail along with temperature data.

In order to run any Nonlinear Creep Analysis, Graphics Systems Simulation team request all users (designers, engineeers and program leads) to work on gathering materail stress-strain curves and creep constants inputs as a  parrallel activity to desgining the parts and assemblies. This will save tremondous time and cost in product development. SolidWorks Simulation Premium, which is integrated within SolidWorks has all features necessary to do Nonlinear and Linear Dynamic analyses.

Most of Graphics/Systems customers recovered the software investment costs within few months time!

Meshhh.......Control..........THAT WAS EASY

I am not saying that generating the mesh is very easy if thats really what you are thinking. We often use the h-adaptive or p-adaptive techniques to get a refined and acceptable mesh. Thats true for the static analysis. How about a frequency or a buckling analysis? Have you every tried using the h-adaptive and p-adaptive mesh for these two studies ? I tried too and did not succeed. However, if you complete the static analysis with the required type of adaptive technique and copy the mesh onto the frequency or buckling analysis, it would let you copy the mesh. Its true that the displacement values obtained from the mode shapes of these two respective studies do not mean much but those of you who would like to use the required adaptive technique, this is the way to go. Well, that was easy.

Another technique I want to share with you is applying the Mesh control. The way you start any study is to first define materials, apply contact conditions, apply loads, generate mesh and run the analysis. This order is very useful when you want to apply the mesh control. Consider faces between any two parts for which the contact set has been defined. If you want to apply a refined mesh control on these two faces, you would pick them one after the other, right ? Some times, this can be painful when you try to hide one part and select the face and repeat the same process for the other face selection. You can also use the "Select Other" option but that can be painful as well with too many clicks. Well, all you need to do is highlight the contact set from the Study tree and then right click on mesh and select mesh control. The faces for contact pairs have already been selected. Well, that was easy, isn't it ?

 

Tips for using Simulation with SolidWorks weldments and gussets

Sometimes using SolidWorks Simulation with weldments can be an interesting experience.  Oftentimes there are more than just structural tubes in the model; plates, made by extruding sketches, co-exist with the weldment members and are used for items such as gussets or feet.  SolidWorks Simulation allows, in a mixed mesh, for solid, shell, and beam elements.  Creating the element groups themselves is not a difficult task and falls outside of purposes of this blog.  I'd like to show you what you can do and what not to do when using mixed meshes and your SolidWorks weldments.

It is very important to understand the degrees of freedom each element type allows for.  Solid elements only permit translational DOFs while shells and beams permit rotational in addition to translational.  Having said that, when a solid and a beam or a solid and shell or a beam and a shell need to exist together, special bonding is required.  Take for example the following image of a portion of a tube frame with a foot pad and a gusset (modeled as a plate).View this photo   The gusset falls on the mid-line of the tube width and would be welded to the vertical and horizontal tubes.  When meshed, it looks like the following image.

You may be tempted to locally bond the thickness face (or midsurface edge if using shells) of the gusset to the "beam" of a structural member.  But this is not possible as beams are 1-D elements and shells and solids are not.  There is no "place" for the software to provide the bonding.  And so, for this case, the structural members will have to be meshed using solids or shells.  (local bonded contacts will still be needed for shell-to-solid meshes)

Another case, as seen in the next image, is where the plate gusset is welded to the outside faces of structural members. In this case, while you still need local bonded contacts, the FACE of the gusset can be bonded to the beam.View this photo

You can see the image of the mesh here to the right.

Lastly, as seen with the footpad solids and beams also need local bonded contacts.  Here however, instead of selecting the beam one needs to select the Joint (not the beam) and the top face of the footpad. Armed with these helpful hints, I trust you will be better equipped to tackle your next Simulation project with SolidWorks weldments and gussets.

FACTOR OF SAFETY.......PLAY IT SAFE

In this blog, I am not going to emphasize on the importance of a Factor of Safety plot as I am sure you all do and are aware of it. While doing the analysis on a single component, we usually create a single Factor of Safety plot and that serves our purpose. But what if our analysis involves an assembly with either 10/100 parts or more ?

How many FOS plots do you need for an assembly ? Yes, the answer is simple : 1 but that's true if you want to check the FOS for the whole assembly. But what about the FOS for each component or set of components only? For 100 components, would you like to create 100 FOS plots ? well, the answer is again simple : NO.

  

All you need to do is create one FOS plot for the entire assembly. Now hide all the components that you do not wish to check the FOS i.e. only those parts that are of interest to us are displayed on the graphics area. Guess what !! the FOS plot automatically gets updated. The legend scale updates and the min and max values are displayed only for the components shown on the screen.

So, the trick here is to create the regular FOS plot and hide/un-hide components to utilize this tool effectively.This is just one of those pocket size power house tools which can give you relatively more info than what it actually appears to be.

How Does One Use SolidWorks Simulation (COSMOS) Efficiently AND Effectively?

Well, in today's global economic world, product development plays key role in any engineering/consulting/manufacturing company. To do product development in time and to introduce quality products computer aided virtual engineering play key role.

 

In order to bring your clay/studio model, which is generally shows RED performance in Virtual Engineering Analysis to GREEN performance level in production version of your product each and every product needs to be checked for following performance criteria in above mentioned product design cycle stages.

·         Component and Assembly level Motion Analysis (Kinematics and Dynamics) for checking Dynamic Interferences and extract loads for Structural Analyses

·         Component and Assembly level Structural Finite Element Analysis(FEA) for checking Stress, Deformation, Fatigue and Buckling Analyses

·         Integration level Vibration / Noise Finite Element Analysis(FEA) for checking Resonant Frequencies and Noise related issues and fixing them

·         Integration level Impact Analysis Finite Element Analysis(FEA) for Checking Nonlinear (Static and Dynamic) performance of the product to get 5 STAR rating for your product

·         Integration level Computation Fluid Dynamics Flow Analysis (CFD) for Flow rate, Drag calculations to improve the efficiency of your product

·         Component and Assembly level Heat Transfer Analysis using FEA and CFD, which helping reducing the heat transfer and balance the energy between the subsystems of the product.

Repeat these analysis for at least twenty five proposed design releases and Optimized the design before the launch of the product.

The SolidWorks Integrated FEA/CFD Code: SolidWorks Simulation (COSMOS) can help your designers and design release engineers can release the integrated parts on time in each stage of your product and reduce the prototype and testing costs for your validation engineers. Thus the chief engineer of the product(s) along with management team will allocate more budgets for doing MORE VIRTUAL ENGINEERING by investing intelligently into Software and Computers and related hardware.

Conclusion:

Thus, by doing a simple product development plan in the product design will enable the organizations to do designs using SolidWorks on time and evaluate the models in very efficient and effective way. Finally, your customer will be spending very less money on warranty issues.

 

Indeed, Its a Dynamic Analysis...

WHAT is it:

Dynamic Analysis constitutes Harmonic, Transient, and Random Vibrations.

WHEN to use:

If an external load depends on the frequency, varies with time or if its non deterministic i.e random.

WHY do we need:

Static Analysis gives us a rough idea of the behavior of the structure. However we shouldn’t neglect the fact that all structures are exposed to operating conditions that are dynamic in nature. The stress level obtained in a dynamic loading is much smaller and closer to the actual stress undergone by the structure in the real time application. Dynamic analysis is of extreme importance when the excitation frequency of the applied load coincides with the natural frequency of the structure to avoid Resonance. Response of the system when subjected to impulsive  load/random vibrations can be carefully evaluated. If a non-linear material is used in such an analysis, it leads to Non-linear Dynamic Analysis. After an excellent description of non-linear analysis in the previous tech blog entry, we will focus on Linear Dynamic Analysis.

HOW to apply:

HARMONIC ANALYSIS

1. Define Material Properties.
2. Specify Restraints (Operating Conditions).
   
3. Apply Harmonic Analysis properties as shown below.
4. Run the Analysis.
5. Predict the results.
   

IMPACT LOADING

1. Define Material Properties.
2. Specify Restraints (Operating Conditions).
   
3. Apply Impact load properties as shown below.
4. Run the Analysis.
5. Predict the results.

RANDOM LOADING

1. Define Material Properties.
2. Specify Restraints (Operating Conditions).
   
3. Apply PSD data as shown below.
4. Run the Analysis.
5. Predict the results.

SUMMARY:

To get the results of any type of analysis is like half battle won. The real challenge is to analyze and interpret the results correctly and correlating to physical test or to its application in the real world. Never expect an even distribution of stress across a symmetrical structure under dynamic loading. The first few natural frequencies are of primary concern and a careful study should be done by plotting the results with the response plot. Avoid resonance by varying the frequency either by adding or removing the material from the structure. Never forget to plug in the damping in the system else the results have little value. Mass Participation factor is also critical for the validity of the results.

Why Nonlinear Analysis Using SolidWorks Simulation Premium?

When to perform Nonlinear Analysis?

Linear Analysis	Nonlinear Analysis
When the material is linear elastic, where the geometry will return to original shape	Linear approximation is fast and efficient solution for many engineering problems. However, most of the real life problems in engineering world are nonlinear
Deformations are small	In many cases, simply understanding the effects of nonlinearity can enable the design engineer to make sound design decisions based on linear results
Loads and restraints are constantly applied to the model, without change in magnitude or direction	Even though nonlinear solution runs take longer time, it replicates the actual physical system being analyzed and the test results will correlate very accurately.

Types of Nonlinearity:

·         Geometric Nonlinearity

·         Contact Nonlinearity

·         Material Nonlinearity

Above types of Nonlinearity exists typically in any assembly made up of any plastic or rubber parts.

Symptoms for Nonlinearity:

•      Stress levels approach the yield point

•      Coupled displacements are restrained

•      Large Displacements are expected

•      Unreasonably High Deflections are observed

•      Two surfaces or curves penetrate

Follow Standard Analysis Workflow:

Stage_1: Assign Material Properties for given parts / assembly connected by correct type of  bonding

Stage_2: Set up operating conditions

Stage_3: Set up Nonlinear Analysis Properties.