What is a 'Dyad Closure'

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

Change Dyad Closure

Icon-R10-DyadClosure32

Mechanism Local Toolbar : Change Dyad Closure icon

Command:

Mechanism menu > Change Dyad Closure

What to do:

1.Click the Green Part-Outline of a Part in a Dyad, in a kinematically-defined Chain
2.Click the Change Dyad Closure icon.
3.Click 'OK' in the Command-Manager

If a Dyad has more than two closures:

4.Do 1 to 3 again and again.

The 'dyad closures' are changed, in the sequence, until you return to the original closure.

Result:

MechDesigner changes the Closure of the Dyad.

Kinematics Tree in Element Explorer

Kinematics Tree

If necessary, use the Kinematics-Tree to identify the Dyad whose closure you want to change.

In the Kinematics-Tree:

1.Click each Solve-Mech' - which is a Kinematic-Chain - to identify the one to which the dyad belongs
2.Expand the Kinematics-Chain, as appropriate

When you click a Dyad, the Part Outlines and Joints show as Red in the graphic-area.

3.Click each dyad in the Kinematics-Chain to identify the dyad whose closure you want to change.
4.Expand the Dyad to show the five element.
5.Click one of the two Parts
6.Click the Change Dyad Closure tool in the Mechanism Local Toolbar.

Do 5 and 6 again and again until the closure of the dyad is the one you want.

What is a Dyad?

A dyad has:

Two Parts
Three Joints.

In the Kinematics-Tree, you will see dyads in Kinematics Chains. They are five different dyads: RRR, RRP, RPR, RPP, PRP, SSR, and SSP dyads.

A Dyad is NOT a:

Slider, Rocker, Motion-Point, Geared-Rocker, Pulley-Rocker.

Dyad Closure?

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

See Kinematic-Closures.

See Also:

Dyads.

tog_minusChange 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.

Then use the Change Closure Tool, Icon-R10-DyadClosure32 , at the bottom of the Mechanism Local-Toolbar.

Dyad-Clousre1

STEP 1: Click a Part-Outline in the Dyad

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

Dyad Closure2

STEP 2: Click the 'Change Dyad Closure' icon in the Mechanism Local-Toolbar.

The icon is at the bottom of the Mechanism Local-Toolbar.

STEP 3: Click 'OK' in the Command Manager

The Dyad Closure changes immediately.

Dyad-Clousre2a

Notes:

It is possible that the Dyad is in a closure that it cannot physically construct 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, do Steps 1, 2 and 3 again
In the case of the RRP Dyad, the Dyad has four(4) closures.

See below.

Dyad Closure 1- RRP

Dyad Closure 1- RRP

Dyad Closure 2 - RRP

Dyad Closure 2 - RRP

Dyad Closure 3 - RRP

Dyad Closure 3 - RRP

Dyad Closure 4 - RRP

Dyad Closure 4 - RRP

Help Files for MechDesigner and MotionDesigner 11.1 + © Machine, Mechanism, Motion and Cam Design Software by PSMotion Ltd