CHAPTER An Introduction to Inventor Simulation In Dynamic Simulation, we divide time into smaller segments also referred to as images chia thời gian thành đoạn nhỏ gọi hình ảnh We calculate the dynamic equilibrium ( cân ) of the mechanism ( chế ) at each time step M M A F A F mass matrix articular accelerations external forces Simulation workfl ow The process( trình ) of creating a Dynamic Simulation study involves four core steps Step GROUP together all components and assemblies with no relative ( tương đối ) motion between them Step CREATE JOINTS between components that have relative motion between them Step Step CREATE ENVIRONMENTAL CONDITIONS(diều kien) to simulate reality ANALYZE RESULTS Phân tích kết STEP : There are two options to group components together, and both have their advantages and disadvantages Option – 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 – Weld components together within Simulation environment Advantage – This method will not alter your BOM database CHAPTER An Introduction to Inventor Simulation STEP : The process of creating joints can be broken down into two stages Stage – Create Standard Joints Stage – Create Nonstandard Joints Stage – There are three options to create Standard Joints, and again, each has its own advantages and disadvantages Option – 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 – 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 Option – 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 – Comprises of creating Nonstandard Joints that 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 : 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 : 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 CHAPTER An Introduction to Inventor Simulation The most time-consuming process when creating a Dynamic Simulation study is Step – creating joints that can be greatly affected by Step – 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 Yes Restructure components into subassemblies environment within the Assembly environment Weld component and subassemblies within the Simulation environment CREATE JOINTS AUTOMATICALLY Activate the Dynamic Simulation Environment if not already activated In the Dynamic Simulation Settings dialog box activate Automatically Convert Constraints To Joints Activate Assembly Constraints dialog box by pressing C Start Creating Assembly constraints 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 degrees of freedom Start creating Non-Standard Joints manually e.g Rolling, Sliding, 2D Contact, and Force Joints CHƯƠNG Giới thiệu mô Inventor Mô giao diện người dung Mô động truy cập mơi trường lắp ráp theo đường dẫn Tab Trình duyệt mơ động Cửa sổ mô động Bảng mô động Chạy mô động CHƯƠNG Giới thiệu mơ Inventor BẢNG MƠ PHỎNG ĐỘNG Thanh mơ động Q trình làm việc Mơ tả Chèn khớp – Tạo tiêu chuẩn khớp chuẩn Chuyển đổi rang buộc – Tạo tiêu chuẩn Khớp đến Bước lựa chọn rang buộc lắp ráp hai thành phần Tình trạng chế –dùng để xác định di động and chế dư lắp ráp bao gồm sửa chữa phần dư thừa khớp Bước Lực – áp dụng lực bên lên thành phần Moomen xoắn – áp dụng moomen xoắn lên thành phần Kết biểu đồ–Dùng để phân tích khớp bao gồm vị trí, vận tốc gia tốc Sự chuyển động– cho phép người sử dụng kiểm tra mơ hình trước chạy mơ toàn Lực ẩn – dùng để xác định lực, mômen, Bước lực cưởng Điều kiện mô Dấu hiệu – Dùng dấu hiệu để tính tốn đầu vị trí thành phần , khớp đầu biểu đồ bao gồm vị trí, vận tốc gia tốc Chuyển đổi đến FEA – Toàn khả di chuyển Bước Bước Phản lực tải đến mơi trường phân tích Xuất phim– bạn cho chuyển động file video Xuấ Studio – You can output your motion to inventor studio for producing cao trả lại hoạt cảnh/ Sự thiết đặt Mô Cung cấp Vài tùy chọn người sử dụng Người chơi Mô Cung cấp công cụ để chơi mô Tham số - Bảng Tham số CHAPTER Giới thiệu mơ Inventor CHƠI MƠ PHỎNG Construction Mode – Sau mơ Có Nished, kiểu xây dựng cần chọn để tiếp tục soạn thảo mô Final Time – Chỉ rõ thờI gian mô Simulation Time – Chỉ đọc giá trị bước bước diễn thờI gian mo Percentage of realized simulation – Đọc giá trị trình bày phần trăm mơ hồn thành Real Time – Chỉ đọc giá trị hiển thị thời gian trôi qua trình mơ thực tế Filter (lọc) – Thơng thường thiết lập để Có thể thay đổi đến giá trị khác 1; đặt 10, mơ bỏ qua tất hình ảnh từ đến 10 mô phát lại Continuous Playback of simulation.( Phát liên tục mô phỏng) Advances to end of simulation Tiến tới kết thúc mô Deactivate screen refresh at each time step – Ngăn chặn việc làm hình bước thời gian, mà giúp tăng tốc độ mô 10 Play simulation Chơi mô 11 Stop simulation 12 Rewind simulation to beginning Cuốn lại mơ để bắt đầu 13 Images – Bình thường bậc cao Số Chính xác Sự mơ phỏng; Tuy nhiên, mô cầm dài để chạy CHAPTER Giới thiệu mô Inventor Thiết lập mô Automatically Convert Constraint to Joint Nếu đánh dấu chuyển đổi tất lắp ráp rang buộc đến tiêu chuẩn lăn khớp để thúc đẩy bánh nhất, thiết kế cách sử dụng thiết kế máy gia tốc Warning –Khi lắp ráp không vững khớp, cảnh báo hiển thị Color Mobile Groups – Gán màu xác định trước cho thành phần điện thoại di động / subassembly AIP Stress Analysis – Sẽ chuyển tải phản ứng với stress tích Inventor mơi trường ANSYS Simulation – Chuẩn bị tập tin với tất kết tải cho ANSYS DesignSpace Location of FEA File – Đây nơi chứa file liệu tải lưu Set Initial Positions – tập hợp tất vị trí đến Reset Joint Positions – Khởi động lại tồn vị trí khớp vị trí góc CHAPTER GiớI thiệu mô Inventor Thiết lập mô nhiều Display a copyright in AVIs – Hiển thị thông tin bạn định tạo AVI Input angular velocity (rpm) – Khi chọn cho phép bạn xác định tốc độ đầu vào vòng / phút 10 3D frames – Thiết lập độ dài trục Z lắp ráp cửa sổ đồ họa Micro-Mechanism Model – Lựa chọn khối lượng quán tính lớn 1e-20 kg 1e-32 kg.m2 chẳng hạn cho phép bạn làm việc với mơ hình chế vi sinh Assembly Precision – Cho phép thiết lập khoảng cách tối đa hai điểm tiếp xúc Điều áp dụng cho 2D liên hệ vịng khép kín Solver Precision – Năng động, phương trình tích hợp cách sử dụng năm để Runge-Kutta Đề án hội nhập Capture Velocity - Đây cú sốc va chạm cho phép bạn giới hạn số bị trả lại nhỏ trước kết liên lạc thường xuyên Giá trị qui định 1, với tối đa lượng tiêu tán Regularization Velocity – Tiếp xúc 2D, thực vi tuyến định luật ma sát dùng, tiếp xúc 3D theo nguyên tắc định luật sử dụng , để tránh siêu tĩnh SỰ ĂN KHỚP Đây có lẽ điều quan trọng vẻ bề tạo thiết lặp mô thảo luận sau : Các loại khớp Các khớp ma trận – Một ảnh chụp khớp dùng sách Qui trình tạo khớp Khớp dự phịng CHAPTER Giới thiệu mô Inventor Các kiểu khớp Mô động, Là năm loại khớp nối, bao gồm tiêu chuẩn ,lăn, trượt, lien kết 2D lực khớp nối Chúng ta thảo luận chi tiết phần sau TIÊU CHUẨN CÁC KHỚP Mô động khớp Lắp ráp tương đương Ràn buộc DOF of joints Sự xoay – không trượt – Quay quanh trục Z Chèn or Trục – trục điểm – điểm Bảng – Trượt dài trục Z – Không quay Mặt – mặt trục -trục Trụ – Trượt trục Z – Quay quanh trục Z Trục trục or biên biên Spherical – No translation – Rotation around all axes điểm - điểm Planar – Translation along X and Z axes – Rotation about Y axis mặt mặt or Tuôn tuôn Point-Line – Translation along Z axis – Rotation around all axes Point and Edge (or axis) Line-Plane Face and Edge (mặt mép ) (or axis) Face and Point (also tangent constraint) Spatial (không gian ) – Translation along all axes – Rotation about all axes Unconstrained ( khoogn bi bắt buộc ) Welding – No translation – No rotation Fully constrained, that is, no DOF between components – Translation along X and Z axes 1 11 – Rotation about Y axis Point-Plane – Translation along X and Z axes – Rotation about all axes 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 further 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 CHAPTER An Introduction to Inventor Simulation CÁC KHỚP LĂN Khớp mô 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( 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 12 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( conical component chỗ) 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 be able to select to create Rolling Joints There is no sliding between components and motion is 2D only The contact remains permanent throughout the simulation CHAPTER An Introduction to Inventor Simulation Output Grapher 81 Specialized Output Grapher Tools Trace – Allows to create traces of components and joints, both visually and numerically (displaying data in Output Grapher) Reference Frame – Gives the ability to examine results in reference to other components and user defi ned origins Export to FEA – Here you specify the component to be analyzed within the stress analysis environment by being able to identify bearing load faces Precise Events – Allows you to determine the precise time of contact or impact events Precise information about contact events is now displayed as a specifi c time step in the Output Grapher CHAPTER An Introduction to Inventor Simulation Output Grapher Tree Here, you have access to all joints data within the simulation Joint data selected here have their values displayed in the graph and time column Graphic Area The graphs of the selected joints data are displayed here Double Click in this area to set a time in the graph that is synchronized to the Time column and the display of the mechanism in the graphics window, and the simulation player You also have the following capabilities within the graphic area ■ Scroll the wheel mouse to zoom in and out of the graph ■ Keep the wheel mouse pressed to pan around the graph ■ Double Click the wheel mouse to reset the graph to its original state Time Column Contains a column for time steps and number of steps matching the time mode images in the simulation player Each of the variables selected in the tree has a column Load Transfer Column Here, you select single or multiple time steps to transfer loads to FEA Apart from simply displaying results of joints as seen in the previous example, the Output Grapher has some advanced specialized tools that will be explained next Output Grapher – Snapshot of tools used throughout the book Environmental constraints 82 Examples were used Design problems were used Traces – Output Grapher data 3,4,5 Traces – Export 4,5 Precise Events Export to FEA 8,9 New Curves/User variables Unknown Force Process of using the specialized tools within the Output Grapher Here again I will try to explain the different tools available to create environmental conditions using the same examples we used in the joints creation process ■ Example – CAM Design Create and Export Trace ❏ Create CAM shape based on trace ❏ ■ Example – Ball and Staircase Precise motion ❏ Export to FEA function is discussed in Chapter CHAPTER An Introduction to Inventor Simulation EXAMPLE CAM Design – Output Trace Workfl ow of Example • • • • Create Trace Export Trace Create CAM – From export trace Play Simulation based on new CAM Extra Joints used in Example • Sliding-Cylinder Curve 83 Create Trace Open CAM3 iam Select Environments tab Dynamic Simulation Select Output Grapher from the Simulation Panel Select Add Trace from within the Output Grapher CHAPTER An Introduction to Inventor Simulation In the Trace dialog box, select the edge of the follower (to specify the origin of the trace) Select CAM Rotating Shaft:1 as the reference geometry to be used to create the trace Click OK Minimize Output Grapher Change the view of the Assembly as shown 84 Play the simulation CHAPTER An Introduction to Inventor Simulation Note that the trace will go up and down This is because we have not specifi ed any rotation of the shaft Select Construction Mode 10 Select dof (R) Tab value box Right Click Revolution:1 joint Enable imposed motion Select Properties Type in 360 deg/s in Velocity 11 Click OK and change view of the Assembly as shown 85 Export Trace 12 Play simulation You should now see the trace of the follower as shown 13 Maximize Output Grapher CHAPTER An Introduction to Inventor Simulation 14 Right Click Trace:1 and select Export to Sketch 15 Select CAM Rotating Shaft as shown 86 16 Close Output Grapher Select Construction mode Create CAM – From export trace 17 Double Click CAM Rotating Shaft This will go into part environment CHAPTER An Introduction to Inventor Simulation 18 Right Click Sketch Select edit sketch sketch Select Finish Sketch Create an Offset of mm of the exported 19 Extrude the sketch by mm as shown 87 20 Click Return to go back to Dynamic Simulation environment 21 Play Simulation You can further refi ne the Input Grapher by adding more points to defi ne a more detailed graph, hence a smoother CAM profi le will be created Alternatively, you can import predefi ned data (in txt format) using the spline law CHAPTER An Introduction to Inventor Simulation Now , as we have designed the CAM we can use this new CAM profi le to drive the follower and hence open and close the valve accordingly Play simulation based on new CAM 22 Select Construction Mode 23 Double Click Cylindrical:3 joint and deselect Imposed Motion Click OK 88 24 Select Insert Joint and select Sliding: Cylinder Curve joint 25 For curve, select edge of new CAM as shown CHAPTER An Introduction to Inventor Simulation 26 Select Cylinder button 27 For Cylinder, select edge of Follower as shown Click OK 28 Play Simulation and after a while, the following warning appears 89 The reason this warning appeared is because the follower misaligned and rotated as shown below If we can stop the follower rotating, we may be able to get simulation to work 29 Click OK Select Construction Mode CHAPTER An Introduction to Inventor Simulation 30 Double Click Cylinder:4 joint and select dof 1(R) Lock Position as shown 31 Click OK Accept warning message 32 Play Simulation 90 Note : Here, the CAM now drives the opening and closing of the valve 33 Close fi le EXAMPLE Ball and Staircase – Precise Events Workfl ow of Example • View impact position of ball • Set precise motion and view results CHAPTER An Introduction to Inventor Simulation View Impact Position of Ball Open ball-stair iam Select Environments tab Dynamic Simulation Play Simulation Select Output Grapher 91 The Precise Events button is selected by default and we can see kinks in the graphs representing the precise motion at contacts Also the timing is not uniformly split CHAPTER An Introduction to Inventor Simulation Deselect the Precise Events button and notice the difference in the curve 92 Now select Force_max variable under Force Joints CHAPTER An Introduction to Inventor Simulation The graph does not display impact forces as the Precise Events button is deselected Set precise motion and view results Select the Precise Events button and see how the graph now shows impact forces at each contact event between the ball and stair Close fi le 93 ... Plane CHAPTER An Introduction to Inventor Simulation Automatically convert standard joints and rolling joints Here , we will create automatic joints from assembly constraints and attempt to analyze... you cannot weld components together that have joints already defi ned between them Select NC-Ball:1 and NC-Rope1:1 Right Click and select Weld parts 19 CHAPTER An Introduction to Inventor Simulation. .. revolution) You may need to expand the components to see the constraints Select Environments tab Dynamic Simulation 25 CHAPTER An Introduction to Inventor Simulation In the Dynamic Simulation browser,