SC-Motion, a motion and dynamic simulation addin inside SpaceClaim has abilities to perform motion (kinematic) and dynamic simulation on SpaceClaim assemblies. The motion at the joint can be a rotation or a translation. These can be supplied as Equations as well, which is covered in the tutorial below (The embedded tutorial file can downloaded here )
A video with example motion equations is below. (The video can be downloaded here )
All the SpaceClaim assemblies and the corresponding motion equations can be downloaded here. The zip file further contains six zip files. Each of these contain SpaceClaim file and a .txt file with equation (for reference).
This tutorial shows how to assemble Bevel Gears (that are imported) in SpaceClaim. These are typically used to transmit motion (and power) in intersecting shafts. They are also used in differential of vehicles, for transmission of power to the wheels.
When bevel gears are imported inside SpaceClaim, we need to define Gear Condition/Constraint between them, which is done by selecting two conical surfaces. The main task is to find out these mating cones. The following diagram shows the equations of determining the apex angle (actually half the apex angle) of cones, given the ratio R1/R2 = N1/N2 (ratio of number of teeth). Once the angles are found, conical surfaces are drawn and gear condition is defined between them.
This tutorial shows how to assemble Worm Gears (that are imported) in SpaceClaim. These are typically used for very high reduction of speed in shafts (hence very high gain in torque) when the space is limited. The axes of shafts are skew and the angle between them is usually 90 degrees.
Update (July 20, 2012): Considered number of starts/threads in the worm in the equations.
When a worm gear assembly is imported inside SpaceClaim, we need to define Gear Condition/Constraint between them, which is done by selecting two cylindrical surfaces. The main task is to find out the radii of these mating cylinders (also known as Pitch Radius). The following diagram shows the equations of determining the radii Rg (Radius of gear) and Rw (Radius of worm) of the two cylinders, given the number of teeth in the gear(Ng), number of threads/starts in the worm (Nw) and the distance between the axes of the gears. We have two equations with Rg and Rw and solving for Rg and Rw is simple.
This tutorial shows how to assemble Rack and Pinion (that are imported) in SpaceClaim. These are typically used to convert the rotary motion applied to the pinion into translatory motion of the rack.
When the rack and pinion assembly is imported in SpaceClaim, we need to identify the pitch circle (or cylinder) of the pinion and the pitch line (or plane) of the rack. We then need to define “Gear Condition” between the cylinder and plane. The following diagram shows the equations for determining the pitch circle diameter of the pinion. Once it is found, a line tangent to this circle and parallel to the rack surface is the pitch line. The circle and line are then pulled to make surfaces, between which Gear Condition is defined.
This tutorial shows how to assemble gears (that are imported) in SpaceClaim. The type of gears considered is “Internal Gears”. These are typically used in planetary gears. This is in continuation of our earlier tutorial on assembling external gears in SpaceClaim. Please go through it to catch up in this tutorial.
Here, we have to find the pitch radii of the internal gear (larger number of teeth) and the external gear (lesser number of teeth). Then, Gear Condition needs to be defined between these pitch cylinders for perfect mating of the gears at hand. The following diagram shows the equations of determining the radii R1 and R2 of the two cylinders, given the number of teeth in the gears and the distance between the centers of the gears. We have two equations with R1 and R2 and solving for R1 and R2 is straight forward.
Make the internal gear as fixed component and define Tangent condition between the mating planes of the gears.
The pitch cylinders are determined in the form of surfaces (which do not add up to the mass of the components).
Gear condition is defined between them.
Edit the property of Gear condition “Reverse Rotation Direction” so that the sense of rotation for external gears and internal gears are same (as opposed to that between two external gears, where the sense of rotation is reversed).
Try to move the external gear. It does not move as required. This is because, the gear condition only makes sure that the relative rotation of the gears are as per the ratio of number of teeth [This is as of SpaceClaim 2012 version].
Define a Tangent condition between the same set of pitch cylinders. Move the external gear and it follows the desired path. This needs to be defined so that external gear and internal gear mesh perfectly.
Go to SC-Motion. Since we do not have a revolute joint to define rotation, we have defined Gravity for the assembly and let the external gear move due to the action of gravity (Dynamic Simulation)
The SpaceClaim assembly file (with Gear condition defined) can be downloaded here.
This tutorial shows how to assemble gears (that are imported) in SpaceClaim. The type of gears considered is “External Gears”. These are typically used to increase or decrease the speed of shafts. Usually, one of the gears has lesser number of teeth (higher RPM/Speed) and the other has larger number of teeth (lower RPM).
When gears are imported inside SpaceClaim, we need to define Gear Condition/Constraint between them, which is done by selecting two cylindrical surfaces. The main task boils down to finding out the radii of these mating cylinders (also known as Pitch Radius). The following diagram shows the equations of determining the radii R1 and R2 of the two cylinders, given the number of teeth in the gears and the distance between the centers of the gears. We have two equations with R1 and R2 and solving for R1 and R2 is straight forward.
GrabCAD is a very good resource to share CAD models and is a bliss for engineers like us. Most of the CAD files we deal at AR-CAD are the assembly files which have some motion in them. Of late, we have been using a lot of their models in our work. In this tutorial we do the following:
SpaceClaim has a distinct advantage that it can import and export files of almost all CAD formats. This lets us import CAD assemblies already available at websites like GrabCAD and use it in SpaceClaim. In this tutorial, we have done the following:
Imported a Solidworks assembly of Backhoe mechanism in SpaceClaim, which we got from GrabCAD.com (By Babak)
Defined Assembly Conditions/Constraints between different parts
Start SC-Motion inside SpaceClaim, which is a completely integrated addin for motion and dynamic simulation.
Brief overview of SC-Motion user interface
Set Joint Translation (Simple Harmonic Motion) to three linear actuators
Set/View Mass and Inertia properties of parts (The tutorial was recorded for SpaceClaim2011, which did not expose mass and inertia properties through its API for us. The values were entered manually. Starting from SpaceClaim 2012 version, they have been exposed. So, in SC-Motion 2012 version, these values are populated automatically, which can be modified for a manual input.
Define Gravity for dynamic simulation
Perform Dynamic Simulation and see the animation.
View and analyse plots of the forces required at the actuators to achieve this motion (This is called inverse dynamics). By doing so, we can get an idea of the maximum force that is required at each actuator and accordingly suitable actuator from the market can be used in actual.
We hope the tutorial would be useful for people to get started with Dynamic Simulation inside SpaceClaim.
Another plus point of SpaceClaim assembly is the way one can move around a particular part and see the effect of its movement on the whole assembly. This can be useful for basic kinematic analysis to determine if the assembly is working as expected or not.
Of all the tutorials(video!) we have watched, we hardly found a set of tutorials which cover creation of a simple SpaceClaim assembly from scratch. We have gone ahead and made the below three video tutorials for people to get started with Assembly modeling in SpaceClaim. The third tutorial in particular is on using SC-Motion, which is a motion and dynamic simulation addin for SpaceClaim.
1) How to model parts in SpaceClaim in an assembly, from scratch ? We have taken example of a Slider-crank mechanism.
2) How to define Assembly Conditions/Constraints between the parts ?
3) Motion and Dynamic Simulation of SpaceClaim assembly using SC-motion.
We hope that watching all the above tutorials would help people to understand the SpaceClaim assembly modeling.