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Hi, can anyone help to please identify the orientation i.e. X, Y, Z, RX, RY, RZ directions of the compliant universal joint in the images attached? - (joint is as per front lower control arm unv joint from multilink template)

Image1 shows the joint definition and coordinate orientation and how it is oriented via two axes.

I've sketched three orthogonal directions and the joint is selected in the image -

1) one along the direction of the control arm to the knuckle hard point --> (is this X direction?)

2) one along the bushing axial direction (mentioned in image2), perpendicular to the 1) direction --> (is this Z direction?)

3) one that is vertical --> (is this Y direction?)

This is to ensure the bush stiffness is applied appropriately in the model

The joint definition is as per front lower control arm universal joint from multilink template

Thank you!

LCA_front_compliant_joint_bush_orientation.PNG

LCA_front_compliant_joint_bush_orientation2.PNG

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English

MotionView/MotionSolve

v2021.1

Accepted answers

GTT Adam

Hi Tahsin,

The orientation of the compliant universal joint is shown in your images, but may be clearer when viewing the same assembly in the new interface (v2023.1):

The directions for X, Y, and Z are clearly displayed, so the Kx, Ky, and Kz stiffness and damping values should follow the displayed orientation markers.

Hope this helps!

Adam Reid

All comments

GTT Adam

Hi Tahsin,

The orientation of the compliant universal joint is shown in your images, but may be clearer when viewing the same assembly in the new interface (v2023.1):

The directions for X, Y, and Z are clearly displayed, so the Kx, Ky, and Kz stiffness and damping values should follow the displayed orientation markers.

Hope this helps!

Adam Reid

Praful

Hi Tahsin - It looks like there are other markers at the same location in your model that makes it unclear on the directions. Deactivating those temporarily might help you visualize better the universal joint marker direction.

Praful

Tahsin Chowdhury_21670

Hi Tahsin,

The orientation of the compliant universal joint is shown in your images, but may be clearer when viewing the same assembly in the new interface (v2023.1):

The directions for X, Y, and Z are clearly displayed, so the Kx, Ky, and Kz stiffness and damping values should follow the displayed orientation markers.

Hope this helps!

Adam Reid

Thank you so much!! I will need to use the latest interface!

Tahsin Chowdhury_21670

Hi Tahsin - It looks like there are other markers at the same location in your model that makes it unclear on the directions. Deactivating those temporarily might help you visualize better the universal joint marker direction.

Praful

Yes! Thank you so much!

GTT Adam

Thank you so much!! I will need to use the latest interface!

Hi Tahsin,

If this solved your issue, please mark the comment as Correct so that future Users can search efficiently for the answer.

Thanks,

Adam Reid

Tahsin Chowdhury_21670

Hi, thank you to both! I do now know the orientation of the LCA joints but still slight confusion as to how it is defined with regard to the plane definition. So to make sure no confusion I had a follow up question regarding the upper shock bush compliant joint as well -- the 00 image shows the confusion in the graphics.

There are other markers from the jounce and rebound marker at the upr shk point which makes it difficult to see/understand the actual orientation but I have hidden them now after Praful's suggestion - (02 image) and understood the coordinate orientation of the upper shock bushing as per the image as follows:

1) X-axis is along the axis of the shock to the shock lower bushing

2) Z-axis is along the line to the ax point (and XZ plane defined)

3) Y-axis orthogonal to the XZ plane and coordinate vector from shk upr point as shown in image

Am I interpreting the definition of this compliant joint correctly?

GTT Adam

Hi, thank you to both! I do now know the orientation of the LCA joints but still slight confusion as to how it is defined with regard to the plane definition. So to make sure no confusion I had a follow up question regarding the upper shock bush compliant joint as well -- the 00 image shows the confusion in the graphics.

There are other markers from the jounce and rebound marker at the upr shk point which makes it difficult to see/understand the actual orientation but I have hidden them now after Praful's suggestion - (02 image) and understood the coordinate orientation of the upper shock bushing as per the image as follows:

1) X-axis is along the axis of the shock to the shock lower bushing

2) Z-axis is along the line to the ax point (and XZ plane defined)

3) Y-axis orthogonal to the XZ plane and coordinate vector from shk upr point as shown in image

Am I interpreting the definition of this compliant joint correctly?

Hi Tahsin,

If I highlight the joints in the multilink suspension model, I do not see an upper shock bushing:

If we look at a macpherson assembly instead, we can see the following upper shock bushing compliant joint has its Z axis pointing to the lower strut rod point:

How it is aligned is shown in the Entity Editor, where only 1-axis (Z axis) is aligned. The remaining X and Y axis are arbitrarily aligned. However, you can change the type to 2-axis to also align a specified plane:

Hope this helps!

Adam Reid

Praful

Hi, thank you to both! I do now know the orientation of the LCA joints but still slight confusion as to how it is defined with regard to the plane definition. So to make sure no confusion I had a follow up question regarding the upper shock bush compliant joint as well -- the 00 image shows the confusion in the graphics.

There are other markers from the jounce and rebound marker at the upr shk point which makes it difficult to see/understand the actual orientation but I have hidden them now after Praful's suggestion - (02 image) and understood the coordinate orientation of the upper shock bushing as per the image as follows:

1) X-axis is along the axis of the shock to the shock lower bushing

2) Z-axis is along the line to the ax point (and XZ plane defined)

3) Y-axis orthogonal to the XZ plane and coordinate vector from shk upr point as shown in image

Am I interpreting the definition of this compliant joint correctly?

I do not see the images that you refer to here. But your interpretation is almost correct.

Minor corrections is on 2) Z axis & 3) Y axis.

The Z axis will be oriented such that a) the point or vector that it is referring to (in this case the ax point) lies in the selected plane (in this case XZ plane) and orthogonal to X axis.

3) Y axis will be orthogonal to XZ plane following the right hand rule for coordinate systems.

Just for learning, you can understand this better if you move the lower shock point or ax point arbitrarily from the default.