What is a 'Dyad Closure'

When it is possible to physically assemble the two parts of a dyad in different ways, such that their motion becomes different, then the dyad has two or more 'Closures'.

Dyads are also called Assur Groups [but not in this help].

See Dyads

Change Dyad Closure

Change Dyad Closure icon

Kinematic Elements Toolbar : Change Dyad Closure icon [<<left of graphics-area]

Menu:

Add menu > Mechanism sub-menu > Change Dyad Closure

What to do:

The dyad must be a kinematically-defined chain [default green Part-Outlines].

In the Graphic-Area

1.Click the Part-Outline of a Part in a dyad whose closure you want to change
2.Click Kinematic Elements Toolbar > Change Dyad Closure.
3.Click OK-tiny-11-15 in the Command-Manager

The dyad re-assembles to a different closure.

4.Do 1 to 3 again to to change the closure again. .
RRR Dyad 2 Parts, 3 Pin-Joints

RRR Dyad
2 Parts, 3 Pin-Joints

in the Kinematics-Tree

In the Kinematics-Tree, find the Dyad whose closure you want to change.

1.Click the Kinematic-Chain that includes the Dyad whose closure you want to change.
2.Click the dyad to confirm it is the dyad whose closure you want to change [the Parts and Joints become Red in the graphic-area].
3.Click a Part in the Dyad
4.Click Kinematic Elements Toolbar > Change Dyad Closure.
5.Click OK-tiny-11-15 in the Command-Manager

Do 1-5 again to find the Closure that you want to use in your model.

tog_plusExample: Change the Closure of the RRP Dyad

Use the Kinematics-Tree to identify the Kinematic-Chain and the Dyad that is in a closure you want to change.

GA-ClosureRRP1

STEP 1: Click a Part-Outline in the Dyad

I have clicked the Part-Outline of the 'Connecting Rod' in an RRP Dyad.

Change Dyad Closure icon

STEP 2: Click Kinematic-elements toolbar > Change Dyad Closure
STEP 3: Click OK-tiny-11-15 in the Command Manager

GA-ClosureRRP2

RRP-4Closures-schematic

The Closure changes immediately.

Notes:

It is possible that the Dyad is in a closure that cannot physically connect the Joints. In this case, when you cycle the mechanism, the Joints will 'brake'. In this case, do Steps 1, 2 and 3 again to find if the joints can assemble.
If after you change the closure of a Dyad it is still not in the correct closure, Change Dyad Closure again.
The RRR Dyad has 2 closures.
The 'offset' RRP Dyad has 4 closures. [see above for schematic]

Tutorial and Reference Help Files for MechDesigner and MotionDesigner 13.2 + © Machine, Mechanism, Motion and Cam Design Software by PSMotion Ltd