PLANAR JOINTS:
NOTE: if you are not familiar with the layout of SolidWorks, then click here to familiarize yourself with the layout. If you are unfamiliar with assemblies please see the assembly tutorial.
There are three types of Planar Joints: Pin Joint, Pin-in-Slot, and Sliding. Solidworks will allow us to study these joints in a way that a simple drawing or schematic would not allow. We will be able to actively move the joints and see the limitations of each joint type.
This tutorial uses files in the parts.zip package. Make sure you download and extract the files to your computer. The assemblies in this tutorial come from the "planar joints" directory. RED pins represent pins that are fixed from translating...each still allows rotation of the body connected to it.
The first Planar Joint is called a Pin Joint. It is one you are already familiar with since it can be seen in most mechanical systems.
It only permits two bodies to pivot relative to another.
As an example of a pin joint consider a scissors lift shown below. This mechanism, which serves to raise platform holding workers, has a series of links which are unfolded by several hydraulic cylinders. Each pair of links is connected by a pin joint which enables them to pivot with respect to each other:
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To examine a simple pin joint in solidworks, follow these steps:
1.) Goto File->Open and select "pinjoint.SLDASM" from the planar joints folder
2.) using the rotate component button 
and the move component button 
see how the pin joint moves in space. Notice the limitations of this joint:
You can see that there are actually two pin joints in this assembly. The pin in a pin-joint could be fixed in position, or it can join two parts, both of which can move.
The second Planar Joint is called a Pin-in-Slot joint. A pin-in-slot joint allows the joined bodies to pivot with respect to each other and to translate with respect to each other in one direction. However translation in the perpendicular direction is restricted.
As an example of a pin-in-slot joint, consider the motorized door opener shown. The end of one member has a pin with a roller, which rolls in a slot in the door:
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To examine a simple pin-in-slot joint in solidworks, follow these steps:
1.) Goto File->Open and select "pininslot.SLDASM" from the planar joints folder
2.) using the rotate component button and the move component button see how the pin-in-slot joint moves in space. Notice the limitations of this joint:
You can see that the link with a slot and a hole is pinned at its hole to some fixed body which is not shown, but that a second link is connected to the slot with a pin. The pin-in-slot joint is that connecting the two links.
ALSO: Notice that you can only translate the link with two holes, not rotate it. This is a limitation of Solidworks. A work around to this problem is to "fix" the link in space by right clicking on link3slide in the Feature Manager Design Tree and click "Fix":
You may get a message that the assembly cannot be solved with this mate. However, you will find that it probably works. Now the link with two holes can be both translated and rotated. You can return to the initial state in which the slotted link floats by right clicking on link3slide in the Feature Manager Design Tree and selecting "Float":
The third Planar Joint is called a sliding joint. A sliding joint prevents two bodies from rotating with respect to one other and permits the bodies to translate with respect to one another only in a single direction.
As an example of a sliding joint, consider the mechanism for adjusting the position of the back to the exercise machine. The black sleeve can only slide on the white member. Notice that the sleeve is locked into position by the spring loaded pin (with the black handle) which engages one of the holes in the white member. But when this pin is retracted, the sleeve can slide. Notice that another link is pinned to the sleeve:
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To examine a simple pin-in-slot joint in solidworks, follow these steps:
1.) Goto File->Open and select "slidingjoint.SLDASM" from the planar joints folder
2.) using the move component button see how the sliding joint moves in space. Notice the limitations of this joint:
You can see that a link with a slot and a hole is pinned at its hole to some fixed body which is not shown. A second member with a square peg engages the slot. While the link with the slot can pivot about its pin joint, the second member can only slide in one direction relative to the slotted link. The sliding joint is that connecting the two links.
Using Planar Joints to Form Mechanisms:
NOTE: if you are not familiar with the layout of SolidWorks, then click here to familiarize yourself with the layout. If you are unfamiliar with assemblies please see the assembly tutorial.
By connecting members of various shapes and sizes with planar joints, the motion (input) of one body brings about the desired (output) motion of another body. Two common input motions are: rotation of a shaft (by a motor) and translation of a body (by actuating a hydraulic or pneumatic cylinder). These are also two commonly desired output motions: pivoting a body about a point and translating a body along a line.
However, the input body often cannot be attached directly to the output body. Therefore, a mechanism converts the input motion to the output motion.
To illustrate this effect, we show three mechanisms which accomplish the same purpose: pivoting a member about a point. The member could be a door pivoting about its hinge:
This tutorial uses files in the parts.zip package. Make sure you download and extract the files to your computer. The assemblies in this tutorial come from the "pivot" directory. RED pins represent pins that are fixed from translating...each still allows rotation of the body connected to it.
Method 1 (Pivot1.SLDASM)
The pivoting member (top) is acted upon by a link (middle), which is in turn driven by a second link (bottom). The bottom link is pivoted by a motor. The motor is not shown, but the shaft of the motor (shown here as a fixed pin) would engage the link causing it to turn. Besides the hinge of the top green member (which is like the hinge of a door), this method involves two pin joints. The mechanism at work here is called a four bar linkage. The "fourth" link joins the two red dots. In the four bar linkage, one link always joins the two fixed pins.
Method 2 (Pivot2.SLDASM)
The pivoting member (top) has a slot in which a pin (blue) slides. The pin is connected to an L-shaped member. The L-shaped member would be pivoted by a motor just as the bottom link above is pivoted by a motor. Besides the hinge of the top member, this method involves a pin in slot joint.
Method 3 (Pivot3.SLDASM)
The pivoting member (top) is acted upon by the piston of a hydraulic (or pneumatic) cylinder. The hydraulic cylinder case is connected to a fixed pin about which it can pivot. The piston is moved back and forth in the case by the flow of compressed fluid or air. As the cylinder extends or contracts, the top member pivots about its pin. Besides the hinge of the top member, this method involves a sliding joint and two pin joints. (The piston and case are connected by a sliding joint.) The mechanism at work here is an inverted version of the crank and slider mechanism.
MATING:
NOTE: if you are not familiar with the layout of SolidWorks, then click here to familiarize yourself with the layout
SolidWorks has a simple, yet powerful mating feature. It is used for joining parts in an assembly and simulating how they fit together and move together. The picture of the engine above shows an intricate assembly. This tutorial will cover the most basic mates that we will use to simulate simple mechanical systems. To use mates we will be working with more than one part and therefore must be in the assembly mode of SolidWorks. To enter this mode follow these steps:
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Start SolidWorks and goto file->new
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Double click the "assembly" icon:
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you will notice a new toolbar appearing to the left of the screen. This is the only noticeable difference between part mode, and assembly mode:
This tutorial uses part files from the parts.zip archive. Make sure you download and extract the files to your computer before continuing...
Concentric Mate:
The most common mate is called a concentric mate, and as the name implies, it is a mate between two concentric features. Any time you want a pinned connection or a piston cylinder type connection you will use a concentric mate. We will mate a pin to a link in the following example:
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First you will add the pin to the assembly. Goto Insert->Component->From File
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Find the "Pins" folder and double click "pin2inch.SLDPRT"
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Click anywhere on the screen to place the part near to where you want it.
NOTE: In solidworks assembly mode ,the FIRST part you insert is automatically fixed in space. This means it can not rotate or translate. Every other part you add is "floated" in space which means it can rotate and translate. For more information about fixing and floating parts please see the Planar Joints Tutorial.
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To add the link follow the same steps for adding the pin. Add "link1.SLDPRT" from the "Links" folder
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Your screen should now look similar to this:
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Select the Mate icon
from the assembly toolbar and mate options will appear. Select the inside face of the hole on the link and the outside face (circumference) of the pin. Watch this animation for clarification:
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Your assembly should now look similar to this:
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To check that the mate worked try moving the link around the screen using the move component button
. The link will remain concentric with the pin, although it can move parallel to the pin (and even off it).
To further restrict our pin we will want to do a second mate:
Coincident Mate:
A coincident mate, like the name sounds, is a mate between two features that you want to coincide with each other. Generally we use it for making two planes parallel and coincident. In this tutorial we will use it to mount the link onto the pin so that it cannot fall off of it. When we do this, the link will spin around the pin, but it will not be able to slide up and down the pin. Follow these steps to achieve this mate:
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Click the mate button
on the assembly toolbar -
Select the top face of the link and the top face of the pin. If you can't easily select the surfaces, use the zoom
and move buttons 
to navigate around the object until you can clearly see the features. Watch the following animation for clarification:
[NOTE: you can also use the middle mouse scroll button to zoom and rotate]
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Your assembly should now look similar to this:
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To check that the mate worked try moving the link around the screen using the "Move Component" button
. The movement of the link movement should be restricted to be concentric with the pin and parallel with the top of the pin.
you are now ready to try mating exercise 1
Try to create the following assembly for more practice:
Troubleshooting:
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it is always a good idea to position the part close to its final mated position before you set up the mate. You can move the part using the move component button
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If you mess up badly, you can always edit->undo. Likewise, if you want to go back to a certain point, you can use the undo list
to see your undo options. If this does not work, Solidworks keeps a record of all mates in the Feature Manager Design Tree under 'MateGroup#' If you expand this list, you can manually delete any mates you have made by selecting the mate and then hitting Delete on the keyboard. Likewise, you can right click and select delete:
MODIFYING PARTS:
NOTE: if you are not familiar with the layout of SolidWorks, then click here to familiarize yourself with the layout
This tutorial will use "link3slide.SLDPRT" from the parts.zip file. You can use these techniques on any part though. The steps in this tutorial are similar to the steps in the dimensioning tutorial. The more you understand solidworks the more you realize that even the most complex parts are made and changed in a similar fashion to the steps in these tutorials.
1.) Use file->open and browse to the links folder. Select "link3slide.SLDPRT" and click open:
2.) You can only add features in sketch mode. To enter sketch mode you must first decide where you want to add the feature. You can add a feature to any plane. You can usually find the sketch under an "extrude" in the feature manager design tree. You will have to click the
to reveal the sketch:
3.) Right click on the sketch and select ‘edit sketch.’ You will notice that the rest of the part disappears or becomes transparent. Do not worry if some of the features of the part become transparent or disappear. They have NOT been deleted. They have simply been removed to simplify the screen and highlight the sketch you are currently working with. See the advanced dimensioning tutorial for an example of "disappearing" parts:
4.) You will now be in sketch mode and can use all the buttons on the right of the screen (picture rotated to save space):
5.) If your view of the part is skewed, click the front view on the standard view menu to rotate the sketch (view->toolbars->standard view):
6.) Your window should now look like this:
7.) To add another hole to the link select "draw circle" from the sketch toolbar:
8.) The cursor changes and you can now draw a circle on the link:
9.) to edit the radius of the circle either follow the steps in the dimensioning tutorial or modify the radius in the feature manager design tree:
10.) Exit sketch mode by clicking the purple arrow in the top, right hand corner:
11.) The new hole will be cut out of the link and your link should now look like this:
12.) To remove the hole you re-enter edit sketch mode. Do this by right clicking on the sketch and selecting edit sketch:
13.) Select the hole you just created by clicking on it with your mouse and hit the delete key on your keyboard. The hole will disappear. Exit sketch mode by clicking on the purple arrow:
You are now ready to try Modification Exercise 1
If you want to modify any extrusion follow this example:
1.) Use file->open and browse to the links folder. Select "link3slide.SLDPRT" and click open:
2.) Right click on "Base-Extrude" in the Feature Manager Design tree and click "Edit Definition":
3.) You will be presented with extrusion options. In this example change the Depth dimension from 1.00in to 3.00in and click the green check mark:
4.) The link will now be three times thicker:
You are now ready to try Modification Exercise 2
for more practice try adding a square hole to the same link:
starting with "linkwithsquareboss.SLDPRT" stretch the boss to 2 inches:
NOTE: make sure you are familiar with the dimensioning tutorial
Troubleshooting:
● If you mess up badly, you can always edit->undo. Likewise, if you want to go back to a certain point, you can use the undo list
CREATING A SIMPLE PART FROM SCRATCH:
The purpose of this tutorial is to create a simple bracket from scratch. Every new part in solidworks begins with a sketch. If you notice this bracket is just a 2d shape that has been extruded to create a 3d object. So to create this part we will create a 2d sketch and extrude it.
1.) Select 'File' -> 'New'' and double click 'Part':
2.) On the main toolbar click 'Sketch' to enter sketch mode. Then click the 'Sketch' button to the right to enter sketch mode:
A set of planes will now appear. Select the plane labeled Front to start your sketch on that plane:
3.) Draw a rectangle starting at the origin. [click once on the origin and a second time at any arbitrary point in the 1st quadrant] :
4.) Click 'Smart Dimension' on the main toolbar and then change the height to .08m and the length to .32m:
For help on dimensioning click here
5.) Now select the 'Circle Tool' and draw a circle similar to the one in the picture below:
6.) Click the circumference of the circle and enter the following values into the panel on the right side of the screen:
These numbers correspond to the absolute location of the circle's midpoint, and the radius of the circle. Namely, the midpoint of the circle is located at (0.25,0.04) and its radius is 0.03m.
7.) Click the little arrow next to the Features button on the main toolbar to bring up the following screen. Then click 'Extruded Boss/Base':
8.) In the pane that appears to the left, enter 0.01m in the box and click the green arrow:
9.) Your model will now look like this:
10.) To create the boss on the surface, you need to start a new sketch on the face of the model. To do this, select the face of the model and click the 'Sketch' button on the main toolbar:
11.) Change to a front view of the model and draw a rectangle using the Rectangle button:
12.) Dimension the rectangle using the 'Smart Dimension' button to be 0.06 m square:
13.) To locate the rectangle in the proper place, use the 'Smart Dimension' tool and select the left edge of the boss, and the left end of the goldish rectangle underneath. Enter 0.01m as the distance:
14.) Repeat this for the gap between the top edge of the boss, and the top edge of the goldish rectangle:
15.) Click the little arrow next to the Features button on the main toolbar to bring up the following screen. Then click 'Extruded Boss/Base':
16.) Enter 0.02m in the D1 box, click the green check mark, and you will get the following model:
CREATING A TRUSS STRUCTURE FROM SCRATCH:
The purpose of this tutorial is to create a truss-like bracket from scratch. Every new part in solidworks begins with a sketch. If you notice this bracket is just a 2d shape that has been extruded to create a 3d object. So to create this part we will create a 2d sketch and extrude it.
before you begin this tutorial make sure you have the 'sketch' , 'sketch tools' , and 'features' toolbars open. Make sure the base units are Meters. Optionally, you may want to turn on the drawing grid. Click here if you don't know how to add these options.
1.) Select 'File' -> 'New'' and double click 'Part':
2.) On the sketch toolbar click 'Sketch' to enter sketch mode. Then click the 'Rectangle' tool:
3.) Draw a rectangle starting at the origin. [click on the origin and drag the mouse to another point and click again] :
4.) Dimension the rectangle using the 'Dimension Tool' and by clicking on two edge's. Change the height to 0.08m and the length to 0.32m:
For more help on dimensioning click here
5.) Select the 'Line Tool' and draw a triangle on the part:
6.) In order to place the triangle exactly where you want it and make it the proper size you must use the 'Dimension Tool.' First you should line adjust the spacing around the triangle. In this example we will change the spacing to 0.01m:
For more help on dimensioning click here
7.) Next you should adjust the length of the triangle's base. Notice the height is already defined. In this example we will the base and height are 0.06m:
8.) Draw and dimension the upper triangle in the same way as the lower triangle. Notice the vertical and horizontal spacing between the two triangles is set to 0.005m:
9.) The sharp corners in the triangles will lead to very high stress concentrations. Fillets are used to lower the stresses in the corners. Use a fillet radius of 0.003m on each corner. To add a fillet, click the 'Fillet Tool,' enter the fillet radius, then click the two lines that create the corner you want to fillet:
10.) Instead of drawing each triangle again, you should use the 'Linear sketch and repeat tool' to add more triangles along the length of the bracket. Using this tool is simple. First select the 2 triangles you want to repeat. Then click the button, choose the number of copies you want, and the spacing between the copies. It will dynamically preview any changes you make. In this example we have 4 triangles, with a spacing of 0.08m.:
7.) Click the purple arrow
to exit sketch mode.
8.) Click the extrude button on the 'Features' toolbar and enter .01m in the d1 text box:
If you want to import this file into ANSYS for analysis, you must save it in the IGES file format. For instructions on how to do this, click here.
Before importing a SolidWorks part into ANSYS, while still in SolidWorks you must export the part in the IGES file format. Click here if you have not done that yet.
MODEL:
START ANSYS AND IMPORT FILE:
Open ANSYS: on cmu cluster machines its under math & stats:
From the file menu select Import>IGES... and select the following options:
Locate your IGS file using the browse button. When you find the file it should look something like this:
Your screen wll now look like this (notice the axis directions):
MATERIAL PROPERTIES:
In order for ansys to do a Fine Element Analysis [FEA] we need to specify what kind of element we want to use. For this 3d solid we will be using a 10 node tetrahedron shaped element[solid187]. To set this click on Preprocessor>Element Type>Add/Edit/Delete:
Click 'Add' on the next window(Elements Type) and then find 'Tet 10 node' under 'Structural Mass' -> 'Solids':
click OK and then click Close on the 'Elements Type' window
Now we must specify what type of material this solid is. The problem specifies the bracket is to be made of aluminum. To enter material data click on Preprocessor>Material Props>Material Models:
Select Structural>Elastic>Isotropic and enter the following numbers into the window that appears:
EX refers to Young Modulus, which is 7e10 Pa for aluminum
PRXY refers to poisson ratio, which is .33 for aluminum
click OK, then close the Define Material Model Behavior' window
MESHING:
To mesh the volume into individual elements, go to Proprocessor>Meshing>MeshTool:
The MeshTool window will pop-up on the right side of your screen. Select the following options and click 'Mesh':
Select the bracket and click ok:
NOTE: If ANSYS gives you an error about going over the maximum number of elements, you must adjust the Smart Size slider to a number higher than 6. The reason for this error is because the educational version limits the maximum number of elements.
Your mesh should look something like this:
While not necessary to solve the problem, for more accurate results it is often a good idea to add more elements in certain areas of interest. This is called Refining the Mesh and can be done by selecting Preprocessor>Meshing>Modify Mesh>Refine at>Areas:
We are concerned with stresses in the holes so add more elements around the holes by selecting the areas that makes up the 2 holes (4 areas in all).
in the next window select 3 and click ok:
Your mesh will now look like this. Notice there are approximatly three times the elements around the circles:
this picture better illustrates the new elements:
BOUNDARY CONDITIONS:
Now we have to apply the loadings to our meshed volume. This problem has 1 mounted area and 1 force.
Before we apply forces you should familiarize yourself with the pan/zoom/rotate tool. You can find it under PlotCtrls:
It has the basic engineering views as well as buttons for rotating about each axis, and buttons for zooming in and zooming out:
Once you are familiar with this tool, you can continue on to apply forces
Since the left side of the bracket is mounted it will not displace in any direction. To set this choose Preprocessor>Loads>Define Loads>Apply>Structural>Displacement>On Areas, select the mounted face and click OK (NOTE: you will have to rotate your view so you can easily select this area):
on the window that pops-up select All DOF and enter a Displacement of 0...the click OK:
To apply the force select Define Loads>Structural>Force/Moment>On Nodes:
You will apply the forces at the end of the bracket, at the two corners. This will make the loading symmetric about the center plane of the bracket. Select the two nodes near the end of the bar (NOTE: select 'iso' on the 'pan/zoom/rotate' tool and zoom in a little to easily select these nodes):
A window will appear asking for the force data. To have a net force of 1200 N, you will need to apply 600 N to each of the nodes you have chosen. Enter the values shown below: Notice a downward force is -600 because the positive y direction points up.
Your bracket should now look like this:
SOLVE:
To run the FEA on the bracket select Solution>Solve>Current LS:
and your bracket will look like this:
POSTPROCESSING:
To see the deformed shape of the bracket select General Postproc>Plot Results>Deformed Shape click OK on the window that appears and your bracket should look something like this:
To get various results for the bracket select General Postproc>Plot Results>Contour Plot>Nodal Solu:
To see the stress in the X direction select the following:
use the 'Pan/Zoom/Rotate' tool to see the 3d stresses. Notice MX and MN locate maximum and minimum stresses
or stress in the Y direction:
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