Chapter 1: An Introduction to Inventor Simulation ppt

– Translation along X and Z axes – Rotation about Y axis Point-Line – Translation along Z axis – Rotation around all axes Line-Plane – Translation along X and Z axes – Rotation ab

In Dynamic Simulation, we divide time into smaller segments also referred to as images.

chúng ta chia thời gian thành các đoạn nhỏ hơn cũng được gọi là hình ảnh

We calculate the dynamic equilibrium ( cân bằng ) of the mechanism ( cơ chế ) at each time step

GROUP together all components and assemblies with

no relative ( tương đối ) motion between them

CREATE JOINTS between components that have

relative motion between them

CREATE ENVIRONMENTAL CONDITIONS(diều kien)

Option 1 – Create subassemblies within the assembly environment.

Disadvantage – Restructuring( Tổ chức lại) your subassembly will affect ảhg your BOM database, hence you

may need to create a duplicate for simulation purposes

Option 2 – Weld components together within Simulation environment.

Advantage – This method will not alter your BOM database

STEP 2 : The process of creating joints can be broken down into two stages.

Stage 1 – Create Standard Joints.

Stage 2 – Create Nonstandard Joints.

Stage 1 – There are three options to create Standard Joints, and again, each has its own advantages and disadvantages

Option 1 – Use Automatic Convert Constraints to Standard Joints.

Advantage – This is by far the quickest way to create joints.

Disadvantages – Can be tedious to go through all joints converted for a large assembly.

– Cannot repair redundancies within the Simulation environment.

– Cannot create Standard Joints within the Simulation environment, with the exception of Spatial joint

Option 2 – Use Manual Convert Assembly Constraints.

Advantages – You can manipulate the type of joint created from constraints.

– You can create Standard Joints within the Simulation environment.

– You can repair redundancies for all Standard Joints not created from constraints Disadvantage – This method is slower than option 1

Option 3 – Create Standard Joints from scratch.

Advantages – You have complete control over how Standard Joints are created.

– You can repair redundancies for all Standard Joints created

Disadvantage – This method is the slowest.

– Does not make use of the assembly constraints

Stage 2 – Comprises of creating Nonstandard Joints that do not make use of assembly constraints and includes the following types of Joints.

– Rolling – Sliding – 2D Contact – Force

Note : Rolling Joints for Spur Gears, designed using Design Accelerator, can be created automatically.

STEP 3 : Once the appropriate joints have been created, the next step is to simulate reality This can be achieved by applying any of the following.

– Joints – Defi ne starting position.

– Joints – Apply friction to joints.

– Forces/Torque – Apply external loads.

– Imposed motion on predefi ned joints.

• Position, Velocity Acceleration (Constant values).

• Input Grapher – Create Specifi c Motions (Nonconstant values)

STEP 4 : This is the fi nal step in which you use the Output Grapher to analyze results in joints, including – Positions/ Velocity/Acceleration

– Reaction Forces – Reaction Torque – Reaction Moments – Contact Forces

The most time-consuming process when creating a Dynamic Simulation study is Step 2 –

creating joints that can be greatly affected by Step 1 – grouping components With this in

mind, I suggest you take the following approach when creating joints

OPTIMIZED WORKFLOW FOR CREATING JOINTS GROUP COMPONENTS/SUBASSEMBLIES

Are you concerned by altering the BOM

No

Restructure components into

sub-assemblies environment within the

Modify assembly constraints to remove redundancies in Standard Joints

e.g change Line–Line constraint to Point–Line constraint; this will change cylindrical joint to Point–Line joint releasing 2 degrees of freedom

Start creating Non-Standard Joints manually e.g Rolling, Sliding, 2D Contact, and Force Joints

dư thừa trong khớp

Lực – áp dụng lực bên ngoài lên một thành phần.

Moomen xoắn – áp dụng moomen xoắn lên thành phần.

Kết quả biểu đồ–Dùng để phân tích khớp bao gồm cả vị trí, vận tốc và gia tốc.

Sự chuyển động– cho phép người sử dụng kiểm tra

mô hình trước khi chạy mô phỏng toàn bộ.

Lực ẩn – dùng để xác định lực, mômen,

và lực cưởng bức Điều kiện mô phỏng.

Dấu hiệu – Dùng dấu hiệu để tính toán và đầu ra

vị trí của từng thành phần , khớp trong đầu

ra biểu đồ bao gồm vị trí, vận tốc và gia tốc

Chuyển đổi đến FEA – Toàn bộ khả năng di chuyển Phản lực tải đến khi căn môi trường phân tích

Xuất bản phim– bạn có thể cho ra chuyển động của file video.

Xuấ ra Studio – You can output your motion to inventor studio for producingcao trả lại những hoạt cảnh/..

Sự thiết đặt Mô phỏng Cung cấp Vài

những tùy chọn người sử dụng Người chơi Mô phỏng Cung cấp những công cụ để chơi sự mô phỏng

Tham số - Bảng những Tham số..

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2 Final Time – Chỉ rõ thờI gian của sự mô phỏng.

3 Simulation Time – Chỉ đọc giá trị các bước bước diễn trong thờI gian mo phỏng.

4 Percentage of realized simulation – Đọc các giá trị trình bày phần trăm của mô phỏng hoàn thành.

5 Real Time – Chỉ đọc giá trị hiển thị thời gian trôi qua trong quá trình mô phỏng thực tế

6 Filter (lọc) – Thông thường thiết lập để 1 Có thể được thay đổi đến một giá trị khác ngoài 1; nếu đặt

10, các mô phỏng sẽ bỏ qua tất cả các hình ảnh từ 1 đến 10 trong mô phỏng phát lại

7 Continuous Playback of simulation.( Phát liên tục mô phỏng)

8 Advances to end of simulation Tiến tới kết thúc của sự mô phỏng

9 Deactivate screen refresh at each time step – Ngăn chặn việc làm mới màn hình ở mỗi

bước thời gian, mà có thể giúp tăng tốc độ mô phỏng

10 Play simulation. Chơi mô phỏng

11 Stop simulation.

12 Rewind simulation to beginning. Cuốn lại sự mô phỏng để bắt đầu

13 Images – Bình thường là bậc cao Số Chính xác hơn Sự mô phỏng;

Tuy nhiên, sự mô phỏng sẽ cầm dài hơn để chạy

Thiết lập mô phỏng

9

1 Automatically Convert Constraint to Joint Nếu đánh dấu sẽ chuyển đổi tất cả các lắp ráp rang buộc đến tiêu chuẩn vàlăn khớp để thúc đẩy bánh răng duy nhất, nếu được thiết kế bằng cách sử dụng thiết kế máy gia tốc

2 Warning –Khi lắp ráp không vững các khớp, một cảnh báo sẽ được hiển thị

3 Color Mobile Groups – Gán một màu được xác định trước cho từng thành phần điện thoại di động

và / hoặc subassembly

4 AIP Stress Analysis –Sẽ chuyển tải phản ứng với stress tích Inventor môi trường

5 ANSYS Simulation –Chuẩn bị một tập tin với tất cả các kết quả tải cho ANSYS DesignSpace

6 Location of FEA File – Đây là nơi chứa file dữ liệu tải được lưu.

7 Set Initial Positions – tập hợp tất cả vị trí đến 0.

8 Reset Joint Positions – Khởi động lại toàn bộ các vị trí của khớp tại vị trí góc của nó

Thiết lập mô phỏng nhiều hơn

1 Display a copyright in AVIs – Hiển thị các thông tin bạn chỉ định tạo ra AVI

2 Input angular velocity (rpm) – Khi được chọn sẽ cho phép bạn xác định tốc độ đầu vào

trong vòng / phút

3 3D frames – Thiết lập độ dài của trục Z lắp ráp trong cửa sổ đồ họa

4 Micro-Mechanism Model –Lựa chọn này khi khối lượng hoặc quán tính lớn hơn1e-20 kg và 1e-32 kg.m2 chẳng hạn như cho phép bạn làm việc với các mô hình cơ chế vi sinh

5 Assembly Precision – Cho phép thiết lập khoảng cách tối đa giữa hai điểm tiếp xúcĐiều này chỉ áp dụng cho 2D liên hệ và các vòng khép kín

6 Solver Precision –Năng động, phương trình được tích hợp bằng cách sử dụng một năm để Runge-Kutta

.Chúng ta sẽ thảo luận chi tiết trong các phần sau.

– Translation along X and Z axes

– Rotation about Y axis

Point-Line

– Translation along Z axis

– Rotation around all axes

Line-Plane

– Translation along X and Z axes

– Rotation about Y axis

Point-Plane

– Translation along X and Z axes

– Rotation about all axes

Spatial (không gian )

– Translation along all axes

– Rotation about all axes

Welding

– No translation

– No rotation

Lắp ráp tương đương Ràn buộc

Chèn or Trục – trục điểm – điểm Mặt – mặt trục -trục

Trục và trục or

biên và biên điểm - điểm

mặt và mặt or Tuôn ra và tuôn ra Point and Edge (or axis)

Face and Edge (mặt và mép ) (or axis)

Face and Point (also tangent constraint)

Unconstrained

( khoogn bi bắt buộc )

Fully constrained, that is, no DOF between components

DOF of joints 1

Standard joints can be automatically converted from assembly constraints by using the

Automatically Convert Constraints to Joints tool( công cụ )

With the Automatically Convert Constraints to Joints tool activated (kích hoạt ) you can continue creating ther Standard Joints by creating more Assembly Constraints within the Simulation environment

The contact remains permanent throughout the simulation

The list of equivalent assembly constraints is not exhaustive

CÁC KHỚP LĂN

Khớp mô phỏng động – There are NO equivalent ( tương đương) assembly constraints

RI Cylinder on Plane This allows ( cho phép ) motion between a cylinder and plane; for example, gear and

a rack.

RI Cylinder on Cylinder This allows motion between two primitive cylindrical components in opposite directions; for example, Spur Gears.

RI Cylinder in Cylinder This allows motion between a rotating cylinder inside another nonrotating cylinder.

RI Cylinder Curve ( đường cong ) This allows motion between a rotating cylinder and a rotating CAM.

Belt This creates motion of two cylinders with the same speed(cùng tốc độ) An option allows rotation in the same direction or as a crossed ( chéo qua) belt.

RI Cone on Plane This allows motion between a conical face and a planar face.

RI Cone on Cone This allows motion between two external(bên ngoài) conical faces; for example, Bevel gears

RI Cone in Cone This allows motion of a rotating conical component within a stationary(ở một chỗ)conical component.

Screw (Vít)This is the same as a cylindrical component but also allows you to specify pitch(xác định cao độ).

Worm Gear This allows motion between a worm gear component and a helical gear component.

Rolling Joints can be automatically created for Spur Gears designed using Design

Accelerator

The primitive(ban sơ ) surfaces are created by Design Accelerator and need to be made visible (rõ ràng) to beable to select to create Rolling Joints

There is no sliding between components and motion is 2D only

The contact remains permanent throughout the simulation

SLIDING JOINTS

Dynamic simulation joints – There are NO equivalent( tương đương ) assembly constraints

SI Cylinder on Plane This allows sliding between a nonrotating cylinder and plane.

SI Cylinder on Cylinder This allows sliding between two primitive cylindrical components in which one cylinder is nonrotating.

SI Cylinder in Cylinder This allows sliding between a nonrotating cylinder inside another nonrotating cylinder.

SI Cylinder Curve This allows motion between a nonrotating cylinder and a rotating CAM.

SI Point Curve This creates motion of a point on one component to stay on a curve, which can be defi ned by a face(s), edge(s), or sketch(es).

You can select sketches, faces, and edges to create joints

The primitive surfaces are created by Design Accelerator and need to be made visible to be

able to select to create Rolling Joints

There is no rotation between components and motion is 2D only

The contact remains permanent throughout the simulation

2D CONTACT JOINTS

Dynamic simulation joints – There are NO equivalent assembly constraints

2D Contact This allows motion between the curve of component and curve of another component.

You can select sketches, faces, and edges to create joints

The motion is 2D only

The contact can be nonpermanent throughout the simulation

FORCE

Dynamic simulation joints – There are NO equivalent assembly constraints

Spring/Damper/Jack This allows you to create springs, jacks, or dampers.

3D Contact This allows you to create contacts between two components It is based

on spring-damper( giảm chấn ) forces.

13

The 3D contact settings are very sensitive ( nhạy cảm ) to change Only change, if necessary( cần thiết ), when model isnot working.

The 3D contact only takes single components into consideration even though the subassembly is

selected So create contacts between all components that have contacts with the subassembly

Joints matrix – a snapshot of joints used throughout the book

used Design problemswere used

14

1 2 3 4 5 6 7 8 9 10

RI Cylinder on Plane

RI Cylinder on Cylinder

RI Cylinder in Cylinder

RI Cylinder Curve Belt

RI Cone on Plane

RI Cone on Cone

RI Cone in Cone Screw

All

2 & 3 4 1

All 4,5 1,3,4,5,6,7 3,4,6

3,6,7 Not used

1 2 Not used

7 Not used

2 Not used Not used

Not used Not used

7 5,7 1 3,6

Process of creating joints

The process of creating joints is probably the most time-consuming process especially

when you have a large assembly This process can be drastically enhanced by being able

to group components that have no relative motion between them There are two options to

do this

Option 1 – Restructure components into subassemblies.

Once the grouping of components has been achieved, there are three options to create

Stand-ard and some Rolling joints

Option 3 – Automatically Convert Constraints to Standard Joints.

Step 2

Option 4 – Manually Convert Constraints to Standard Joints.

Option 5 – Manually create Standard Joints.

Here , I will attempt to explain the above options of grouping components and creating

joints by using a series of examples

■ Example 1 – Newtons-Cradle – Options 1 and 2

■ Example 2 – Whitworth Quick Return Mechanism – Option 3

■ Example 3 – Slider Mechanism – Option 4

■ Example 4 – CAM Follower Mechanism – Option 5

EXAMPLE 1

Newtons-Cradle – Grouping Components Workfl ow of example 1

• Automatically convert constraints to standard joints

• Restructure parts into subassemblies

• Weld parts together

• Lock joints degree of freedoms Joints used in example 1

• Revolution

• Spherical

• 2D Contact

15

Automatically convert constraints to standard joints

1 Open Newtons-Cradle1 iam

Chúng ta sẽ thấy có 7 viên bi và 7 sợI dây Có một điểm ràng buộc giữa quả bong và sợI dây, và một điểm ràng buộc giữa sợI dây và sườn Trong toàn bộ có 3 rang buộc và mỗI cặp bong kiên kết nhau

2 Select Environments tab Dynamic Simulation

This will activate the Dynamic Simulation environment.

17

In the Dynamic Simulation browser, notice that a spherical( cầu) joint is created between the ball

and rope (Mate:1 – Point constraint), and a revolution joint is created between the rope and

frame (Mate:2 – Point constraint and Mate:3 – Axis Constraint) This is done seven times so

14 joints are created in total

To see how simulation converts constraints to joints refer to page 11 Standard Joints and see

how constraints are converted to joints (this table is not exhaustive) Also note the number

of joints created is not related to the number of constraints

Another point is that you can create rigid groups automatically by adding more constraints For

example in this case by adding a mate constraint between a plane of the ball, and one of the

ropes, we will lock all degrees of freedoms between these 2 parts Dynamic Simulation will then

create a rigid group containing the ball and the rope (as if you manually created a weldment)

For the Newtons-Cradle to work properly, the rope and ball will need to move together such

as there will be no relative motion between the ropes and balls With this in mind, we can

restructure the ball and rope components into one subassembly; this will hopefully simplify

the joints process by reducing the number of joints created

3 Close Newtons-Cradle1 iam fi le

Restructure parts into subassemblies

4 Now open Newtons-Cradle2 iam fi le

You will now see 7 subassemblies, each containing( chứa) one ball and associated rope.Additionally, there is now one point and axis constraint between the subassembly and frame

In total, there are now 2 constraints for each subassembly

5 Select Environments tab Dynamic Simulation

In the Dynamic Simulation browser notice there are now 7 joints instead of the original 14joints

Restructuring ( sắp xếp lại) your components into subassemblies, like this, will affect your bill of materialsdatabase as now instead of having 7 balls and 7 ropes it will have 7 subassemblies If you do

not want to affect your bill of materials or want to create another assembly for simulation

purposes, the only alternative(xoay chiều) is to weld components together within the simulation environment before you create the joints, automatically or manually

6 Close Newtons-Cradle2 iam fi le

Weld parts together

7 Now open Newtons-Cradle3 iam fi le

8 Select Environments tab Dynamic Simulation

All components are now grounded as no joints have been defi ned between them, and the

Automatically Convert Constraints to Standard Joints button is deactivated This is important

because you cannot weld components together that have joints already defi ned between them

9 Select NC-Ball:1 and NC-Rope1:1 Right Click and select Weld parts 19

Now notice that both components are welded together as one This is the same as restructuring components together as subassemblies but without affecting the Bill of Materials database

You cannot use Automatically Convert Constraints to Joints, as this will not take into account

that you have manually welded components together So, now you will need to convert the

joints manually, either by converting constraints to joints or by using the Insert joint tool We

will use the former method, and this is further used in Example 3 – Slider mechanism

10 Select Convert Constraints

This will enable( kích hoạt) you to create joints from existing Assembly Constraints manually

11 Select the 1st Rope and Frame as the two components that need their constraintsconverted to joints

In the Convert Assembly Constraints dialog, the two constraints, between the new welded

component and the frame, are converted to a revolution joint, as expected

You will need to repeat steps 9–11 six more times to complete the standard joints process for

all components

We had to create two assembly constraints between each subassembly (or welded group) and

the frame, to achieve the desired revolution joint We can achieve this same effect by only using

one point constraint between the subassembly and frame, thus eliminating the time needed to

create extra constraints This is outlined below

12 Close Newtons-Cradle3 iam

Lock joints degree of freedoms

13 Open Newtons-Cradle4 iam

You will see that there are still 7 balls and ropes subassemblies But the difference now is that

there is only one point constraint between each subassembly and frame In total, there are

now 7 constraints rather than 14 as in the previous example

14 Select Environments tab Dynamic Simulation

21

You will now see that 7 spherical(cầu) joints are automatically created, instead(thay thế) of a revolutionjoint This is because we only used the point constraint between the two components

We will now alter these spherical joints to behave like revolution joints without need to

cre-ate more assembly constraints

15 Select all Spherical Joints Right Click and select Properties

16 Select dof 2 (R) Tab in the Joints dialog box Lock the position as shown

We have just locked the rotation about this degree(bậc) of freedom (tự do)

We will further discuss joints properties later within the Environmental Constraints Section

17 Select dof 1 (R) Tab Lock the position as shown

We have just locked another rotation of the spherical joint This will now make the spherical

joint behave like a revolution joint

18 Click OK

All joints now have a # symbol assigned to them, meaning the joints have locked degrees

of freedom

Now , I hope you can appreciate (đánh giá ) that by simply restructuring the components into

subassem-blies and welding components together can have signifi cant impact on the number of joints

created We will now discuss how to create joints in more detail

19 Close Newtons-Cradle4 iam

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EXAMPLE 2 Whitworth Quick Return Mechanism – Automatic Joints

• Automatically convert Standard Joints and • Revolution

• Create other Nonstandard Joints • Point-Line

• Rolling – Cylinder on Cylinder

Note : The only Rolling Joints that can be converted • Sliding – Cylinder on Plane automatically are between Spur Gears that have been

created using Design Accelerator.

Automatically convert standard joints and rolling joints

Here , we will create automatic joints from assembly constraints and attempt to analyze how

Dynamic Simulation creates joints

1 Open Whitworth Quick Return iam

In the Assembly browser, notice that four parts are grounded and the remaining( còn lại) four

components are constrained predominantly(mạnh hơn) using the insert constraint (equivalent joint

is revolution) You may need to expand the components to see the constraints

In the Dynamic Simulation browser, notice that the components grounded in the assembly

environment remain grounded within Dynamic Simulation The rest (cột, đứng yên) of the components

including Spur Gear subassembly become part of the mobile group; this is because the

assembly constraints between these components have been converted automatically to

Standard and Rolling Joints

For Dynamic Simulation to convert Spur Gear (created by Design Accelerator) constraints to

Rolling Joints, do not alter (sử đổI) the hierarchy(trật tự ) of the subfolders (danh mục con ) created by Design Accelerator The reasons (ráp lại)why constraints are created automatically to joints is because automatically

convert constraints to standard joints is activated()kích hoạt ) within the dynamic simulation settings We

will check this in the following steps

3 Select Simulation Settings

Within the Dynamic Simulation Settings dialog box, we can see Automatically Convert

Constraints to Standard Joints is activated

4 Click Cancel Now , we will attempt ( gọI lạI )to analyze the joints converted from Assembly Constraints

■ Revolution:3 Joint – Indicates (chỉ rõ )result as predicted (dự báo )

welded joint between both components as if they were welded together in reality

■ Pointed-line:4 Joint – Not as predicted – Expecting a revolution joint – Insteadcreated a point-line joint creating extra three degrees of freedom ( bặc tư do ) between the twocomponents

The only explanation for this is to avoid creating redundant( siêu tĩnh) joints (joints

overcon-strained) dynamic simulation has created the joints and welded bodies as illustrated ( minh họa ) below bên dưới

Redundant Joints are discussed in detail( bộ phận) later ( chậm hơn )in the chapter

The only way to alter the converted joints is to modify the assembly constraints and this

process (chế tạo )can become tedious( chán), especially for a large assembly with redundant joints

Another option is to manually convert constraints, but this option is disabled (mất tác dụng) when the

Automatic Conversion of Constraints is activated as shown below This option gives you

more control on how joints are created and this process will be illustrated in Example 3

For now, we will continue with Example 2 to create more nonstandard joints

27

Create other nonstandard joints

Here , we will create one more sliding joint to complete the mechanism

5 Select Insert Joint

6 Select Sliding Cylinder on Plane joint from the list

7 To define Plane select edge of Slot-Case:1

8 Select Cylinder button of Component 2 Select Edge of Spur Gear 1 to complete the joint

9 Click OK The following sliding joint will be created

10 Close Whitworth Quick Return iam

EXAMPLE 3

Slider Mechanism – Manually (thủ công )Convert Constraints

• Manually convert Standard Joints from • Revolution

• Repair redundant joints • Prismatic

29

Manually convert Standard Joints from Assembly Constraints

Here , we will create joints manually by converting existing Assembly Constraints

1 Open Slider-mechanism.iam

2 Select Environments tab Dynamic Simulation

In the Dynamic Simulation browser, notice that all components are grounded because matic (hạn chế ) conversion of constraints is switched off within Dynamic Simulation

auto-3 Select Convert Constraints

4 In the Convert Assembly Constraints dialog ( hộp thoại ) box, select Bracket and Arm 1

In the Convert Assembly Constraints dialog box, the Insert assembly constraint appears (xuất hiện ) that

was used to constrain the two parts in the Assembly environment

Dynamic Simulation has suggested (đề xuất )an equivalent revolution joint

31

5 Click Apply Clicking Apply instead of OK leaves the dialog box open so you can continue

converting constraints

That Revolution:1 (Bracket:1, Arm1:1) joint is created under Standard Joints as illustratedbelow This joint creation process has also made Arm1:1 mobile The reason why Arm1:1component is made mobile is because Bracket:1 component is grounded from the Assemblyenvironment and hence remains grounded, within the Simulation environment

6 Select Arm1:1 and Arm2:1 components to create a 2nd joint between the selectedcomponents

Dynamic Simulation has automatically detected two constraints between these componentsand as a result has suggested a revolution joint

7 Now deselect Mate:2 constraint and see how the joint created now changes to a

Cylindrical Joint

The reason( nguyên nhân) for this is because Mate:1 (Arm1:1, Arm2:1) is an axis-axis constraint that allowsrotation about, and translation along, the edge/axis

8 Now reselect Mate:2 and deselect Mate:1 and see how the joint has now created

changes to a Planar Joint

33

The reason for this is the Second Mate:2 (Arm2:1, Arm1:1) is a face-face constraint, which

allows movement ( hành trình) along a 2D plane only

By selecting both constraints we are further restricting( thu hẹp) the motion of the components, such

as reducing the degrees of freedom of the selected components

9 Reselect both constraints Click Apply

10 Select Arm 2 and Slider Click Apply

Reason why a cylindrical joint is suggested is because Mate:4 is an axis-axis constraint

11 Finally, select the Bracket and Slider components Click OK

Mate :3 is an edge-edge constraint and Flush:1 is a face-face constraint; hence Dynamic

Simulation suggests a prismatic joint

12 Click OK to accept the Dynamic Simulation warning

That Prismatic:4 joint is created under Standard Joints as illustrated below In total,

4 joints have been created

By accepting the above warning, Cylindrical:3 joint has now become a redundant joint

This means the joint is overconstrained by two degrees of freedom as mentioned in the

warning

The redundancy phenomenon will be discussed later, but in the meantime, we will

deter-mine how we can remove redundancy from this joint

Repair redundant joints

To resolve Cylindrical:3 (Arm2:1, Slider:1) joint you can either

a Alter ( thay đổi )the joint/constraint to allow for more degrees of freedom ( tự do );

b Alter any of the other joints; or

c Use repair redundancies( độ dôi) button( chốt) to automatically resolve the issue( phát hành )

We will use option a, as option c is not available as we have created joints from assembly

constraints

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13 Select Mechanism Status

14 Click on the exclamation mark to determine possible solutions

15 Click OK twice

As soon as you click on the exclamation mark, the warning appears suggesting that the jointcannot be automatically repaired as it is a translated joint and can only be repaired by edit-ing the constraints It also suggests that by using a Point-Line Joint the model will have noredundancies A Point-line constraint is basically a spherical joint with one translationaldegree of freedom

16 Select Mate:4 Right Click and select Edit

You may need to expand the Cylindrical:3 joint to see Mate:4 constraint

17 In the Edit Constraint dialog box, Click on 2nd selection Select the edge of the

Slider (Red) Click OK

Cylindrical:3 (Arm2:1, Slider:1) redundant joint has changed to: Point-Line:3 (Arm2:1,

Slider:1) nonredundant joint as illustrated below

18 Close fi le

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EXAMPLE 4 CAM Design – Manually(bằng tay) Create Joints

Manually create standard joints

Workfl ow of Example 4

• Manually create Standard Joints

• Weld components together

• Continue manually creating joints Joints used in Example 4

2 Select Environments tab Dynamic Simulation

All of the parts are shown under the Grounded node because no joints have been applied or

created

3 Select Insert Joint from the Dynamic Simulation Panel

In the Insert Joint dialog box, the Revolution joint will be the default joint

4 Select CAM Rotating Shaft as shown for Component 1 Selection

By selecting the component as shown, the origin of the joint is in the middle of the shaft If

we want to maintain the position of the shaft, we also need to specify(ghi rõ) the origin(góc) of the joint

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5 Click on Workplane as shown to defi ne the origin of the joint axis for Component 1

6 Select the Component 2 button and select the top face of the bracket as shown

7 Select the edge of the bracket to defi ne the origin of the axes for Component 2

Both axes have the same origin but Z axes are in the opposite directions We need to fl ip thedirection of the Z axis for Component 2, otherwise the components will not maintain theiroriginal position

8 Select the Flip Z axis button as shown to fl ip the direction of the Z axis Click OK

Revolution:1 joint is created under Standard Joints as illustrated below

9 Click on Insert Joint tool again to create a revolution joint

10 For Component 1 Z axis defi nition, Click on the edge of Component 1 as shown

11 Select the Component 2 button and select the edge of the Component 2 as shown

The axis origin and the Z axes align correctly Selecting the edge of a component also defi nes

the origin

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12 Click Apply

Revolution:2 joint is created under Standard Joints as illustrated above

13 In the Insert Joint dialog box, select Cylindrical Joint from the pull down menu asshown below

14 Select Camshaft face as shown to defi ne Z axis of Component 1

As the Camshaft is in the close position, we also need to defi ne the origin so Component 1does not move

15 Select the work plane as shown to defi ne the origin of the joint