ANSYS v17 Update Seminar. Presented by: CAE Associates

Transcription

1 ANSYS v17 Update Seminar Presented by: CAE Associates

2 Multiphysics Analysis using ANSYS v17

3 Demonstration of ANSYS/Multiphysics Scenario: Your company designs and manufactures gear boxes. You recently switched your gears supplier and are now experiencing an increase in field failures. The gear supplier is claiming that the failures are not their fault. You are tasked with determining the root cause of the and the modifications required to correct the problem. The issues you need to contend with are as follows: You do not have a CAD file of the gear. You use induction heating to assemble the gear and shaft. You need to determine if the resulting assembly loads are contributing to the field failures. 3

4 Demonstration of ANSYS/Multiphysics The approach will be as follows: 1. Scan the actual gear and use reverse engineering to generate CAD geometry using SpaceClaim. 2. Calculate the ohmic losses of the induction heating process of the gear using Maxwell. 3. Calculate the resulting temperature distribution in the gear using Fluent. 4. Assemble the gear/shaft and calculate the residual stress using Mechanical. 5. Add the operational load and estimate the life of the gear using the Fatigue Tool. 4

5 Demonstration of ANSYS/Multiphysics Extra credit: You have observed surface cracking on some of the gears. Determine if the cracks will propagate under load. 5

6 ANSYS SpaceClaim Direct Modeler Eric Stamper

7 ANSYS SpaceClaim Direct Modeler SpaceClaim brings 3D modeling to the desktops of engineers and analysts who work with but don t want to become experts in traditional featurebased CAD systems. ANSYS SpaceClaim Direct Modeler (ANSYS SCDM) software is a new way to manipulate CAD models and is integrated into Workbench. The model becomes completely dynamic, allowing the user to move, stretch, add and remove features with ease. All changes to the CAD model occur in real time on the screen, providing instant feedback on a design. ANSYS SCDM addresses the specific needs of the finite element analyst, including simplifying existing CAD geometry, creating detailed and complex geometry, and allowing parametric modeling. 7

8 SpaceClaim v17.0 Reverse Engineering Gear Demo

9 Overview of Reverse Engineering What is Reverse Engineering? The process by which a physical component is converted into a 3D CAD model. A faceted geometry file can be created by scanning a physical part and connecting all the point cloud measurements into triangular surfaces. The result is a faceted surface representation that can be saved in a.stl file format. The faceted geometric representation is then converted back into an analytical and manufacturable representation. ANSYS Reverse Engineering Solution: The Faceted Toolkit within ANSYS SpaceClaim Direct Modeler can be used to manipulate the surface facets and provide the user with a geometric guide from which a new CAD model can be recreated. 9

10 Overview of Demo Reverse Engineering Strategy: Use the faceted surfaces as a guide to rebuild a new CAD model. Solid geometry can be created directly from the faceted surfaces; however the resulting CAD model will typically be poorly represented. Cleaning up all the poorly represented surfaces of the CAD model is generally more difficult than dealing with the surface facets directly. Reversed Engineered STL Direct STL to CAD 10

11 Reverse Engineering Gear Demo Open: Gear_Coarse.stl Right click on the Facet Mesh object in the tree > Convert to solid > Merge Faces. The faceted surface model is now converted into a solid, however it s very faceted and poorly represents the physical part. Manual clean up will be needed to improve the geometry. The Faceted toolkit tab is designed to work with these types of surfaces before a 3D solid is created. Undo this operation! 11

12 Reverse Engineering Gear Demo Click on the World Origin in the modeling window Click the plane icon to create the 3 orthogonal global planes. 12

13 Reverse Engineering Gear Demo Click the vertical plane in this view Select Move Tool Check box Create patterns Drag green angle on triad over to create 1 plane as shown Click on Pattern in the tree Change the properties as shown 13

14 Reverse Engineering Gear Demo Click the vertical plane in this view Select Move Tool Check box Create patterns Drag green angle on triad over to create 1 plane as shown Click on Pattern in the tree Change the properties as shown 14

15 Reverse Engineering Gear Demo Facets Tab > Split Use planes to split.stl Delete unneeded features: Select anything on the yellow body and the two planes that sliced it Ctrl+H to hide them Ctrl+A to select all Delete key to delete everything shown RMB click, show all 15

16 Reverse Engineering Gear Demo Insert Tab > Extact Curves Orient normal and zoom in V then Z Click Checkmark Use front plane 16

17 Reverse Engineering Gear Demo View in 3d D Hide all but the lines to show that the x-section was extracted Orient view normal to plane Click plane, then V Repair Tab > Fit Curves Check Correct Tangency Box select curves shown Use slider to show how the curves are fixed. Go with Max. dist = 0.2mm Click green check to complete Box Select 17

18 Reverse Engineering Gear Demo Repair Tab > Fit Curves Repeat box selections to fix other locations Box Select Box Select 18

19 Reverse Engineering Gear Demo Turn on Facet Mesh to see the lines against the edges Zoom to bottom Select edge and fill f to replace curve with line Fill twice to remove chamfer to corner 19

20 Reverse Engineering Gear Demo Show just curves Fill edges shown Box select these 4 edges and fill once more to replace with single edge Select all edges and Fill to convert to surface 20

21 Reverse Engineering Gear Demo Show just the facets Facets Tab > Smooth Double click faces to select all facets in hole, top and bottom surfaces, then smooth twice 21

22 Reverse Engineering Gear Demo Double click facet in hole to select all facets in hole Then: Insert Tab > Cylinder. Pull faces just to make it a little longer and not co-planar with the facet surface 22

23 Reverse Engineering Gear Demo Show just the mesh and zoom in as shown Double click the facets to select shown as show. Use Ctrl+Double click as need to add the right facets, then Insert > Fit Spline (REPEAT) 23

24 Reverse Engineering Gear Demo The surfaces will eventually be used to cut away the teeth First trim surfaces with planes Make sure the planes are slightly off the surfaces of the mesh. Use orange facets to initially place plane Design Tab > Plane Click newly created plane and Move M Drag up slightly with z direction 24

25 Reverse Engineering Gear Demo Whilst in the move tool, hold Ctrl, and drag down a copy of the plane just off the surface of the lower gear face Show just the surfaces and planes Use Design > Combine with box select and trim away extra surfaces. 3. Click 4. Box Select 2. Box select 1. Repeat 25

26 Reverse Engineering Gear Demo Imprint all surfaces Prepare Tab > Imprint Select unused surfaces and delete 26

27 Reverse Engineering Gear Demo Create a solid from the surfaces. Select the two edges shown, Design Tab > Blend Box select edges Use fill to create solid 27

28 Reverse Engineering Gear Demo Pull edges to 0.75mm Save this value as a parameter by clicking the P, now making the blends parametric. Go to Groups Tab to see it. Show all, put axis on global z Design Tab > Axis 28

29 Reverse Engineering Gear Demo Only show surface Pull Revolve surface 360 around axis 2. Click 1. Click 3. Click Subtract hole solids Show hole body With combine. 1 st click gear, 2 nd click box select hole body, 3 rd click box select hole bodies. Click hole body in tree, delete 29

30 Reverse Engineering Gear Demo Pattern the holes with Move: Click surface 4. Use or drag yellow triad to global axis Click Use blue angle arrow to create pattern 30

31 Reverse Engineering Gear Demo Options to create the teeth: 1. Move body to create a pattern of the teeth solids and then subtract 2. Subtract 1 tooth and move faces to a pattern 3. Subtract 1 tooth and pattern faces Show OR 31

32 Reverse Engineering Gear Demo Create chamfer Select 1 edge Go to Selection and use search to find all edges on face Use Pull, and select Chamfer Pull to 2.5mm 32

33 Reverse Engineering Gear Demo Create chamfer Manually, just select a couple edges to show additional pull. Pull with Pivot Edge Matched 2. Up to 1. Direction 33

34 Summary: Reverse Engineering Gear Demo The faceted surface representation (STL file) of the gear was converted into 3D CAD model and is ready to be used in an analysis. The STL file served a guide from which surfaces and curves were extracted and used to build new features. The main tools used to reverse engineer the gear were: Pull, Move, Fill and Combine STL Reversed Engineered 34

35 Highlighted Features in SCDM V17 For detailed release information visit:

36 New Skin Surface Feature Interactively generate surfaces over faceted models Skin Surface supports: 4-sided, 3-sided, domed, and periodic patches Tightness control Direct editing of patch boundaries Connecting of neighboring patches Automated smoothing Auto-skin from planes 36

37 New Scripting (Beta Release) Automate geometry creation and cleanup IronPython based Editor in SC for script creation and execution Access to math and any Python library 37

38 v17 Update Agenda 8:30 Welcome Introduction Pass out the question cards What s new, website additions, etc. 8:45 New Product Packaging 9:15 Coupled Field Demo: Reverse Engineering Geometry Induction Heating with Maxwell 10:15 Break 10:30 Coupled Field Demo continued: Conjugate Heat Transfer using Fluent Structural Analysis using Mechanical HPC 12:00 Lunch Assembly and operational loading Estimating life with the Fatigue Module Fracture Analysis 1:00 Customer Q&A 1:30 CFD Update 2:30 New Mechanical tools Simulation for Electronic Products Model Assembly Mechanical Features Adaptive meshing 3:15 Break 3:30 Product update details ACT Topological optimization Example APDL ACP XFEM 38

39 ANSYS Electromagnetic Simulation Jim Kosloski

40 Why Do Electromagnetic Analysis? Gain a better and more detailed understanding of the response and behavior of an electromagnetic device. Virtual prototyping = Time and cost savings Safe virtual testing of dangerous operating environments. Design sensitivity studies allow efficient assessment of changes in electric loading and environmental conditions. 40

41 Example Electromagnetic Problems Capacitor Compute the electric field between and around the conducting plates. Calculate capacitance. Brakes in electric cars store energy in capacitor Motor/Generator Analyze the magnetic field in a motor due to coil windings or permanent magnets. Study fringing and field results across the air gap. Calculate flux linkage, inductance, reactance, force and torque. Solenoid Analyze the magnetic field and force generated. Induction heater Determine the electric and magnetic fields in a part induced by an alternating current in an adjacent coil. Determine the losses (heat generations) in the part due to the induced currents 41

42 Example Coupled Field Problems Torque (N) Electromagnetic calculations are often used in conjunction with other field solutions: Example: Objective: Predict Electric Motor Performance Design for real-life operating conditions with a wide variety of loads and manufacturing variability. Solution Calculate electromagnetic loss and use these results to calculate the thermal effects with CFD Look at further thermal and stress analysis in a structural analysis. Value of Simulation In this case, the actual magnet temperature was more than 30 degrees C higher than the assumed one with a corresponding big hit in performance. Including all the physics provides a more thorough understanding of how your product operate. Electromagnetic CFD Mechanical Y1 [NewtonMeter] Torque Time [ms] Time (ms) Single physics simulation, assuming a magnet temperature of 22C 3-way Multiphysics simulation shows that the actual magnet temperature: 53C 16% drop in predicted performance Curve Info Moving1.Torque Setup1 : Transient 2D Moving1.Torque_22_ Imported Moving1.Torque_2em Imported Moving1.Torque_3em Imported 42

43 ANSYS Maxwell ANSYS Maxwell is an industry leading high-performance interactive software package that uses finite element analysis (FEA) to solve electric or magnetic problems. Maxwell solves the electromagnetic field problems by solving Maxwell's equations in a finite region of space with appropriate boundary conditions excitations and initial conditions in order to obtain a solution. 43

44 Maxwell Strengths Ease of use brings usability and productivity Adaptive Mesh Technology Automatic and complete workflow setup generation for electrical machines Transient with rigid motion and circuit coupling. Multi-physics and robust design. Workbench integration (CAD integration, multiphysics, automated load transfer) Parametric variations Optimization, DOE, DFSS. Advanced material modeling Permanent magnet magnetization and demagnetization. Permanent magnet temperature dependency. Core Loss Calculation (electrical steel and ferrite) with feedback on field solution. High Performance Computing capabilities Use of multiple cores to solve frequency sweeps 44

45 Maxwell and Workbench Maxwell is integrated in Workbench environment. The main advantages of this integration for the user are: Multiphysics analysis. Maxwell is coupled to ANSYS Mechanical (thermal and stress solver) and Fluent (thermal) CAD Integration. Through Workbench, Maxwell has bi-directional link with CAD sources. Parametric variations 45

46 Maxwell GUI 46

47 Maxwell Solvers Magnetic Solvers Magnetostatic Solver Solves Static magnetic fields caused by DC currents and permanent magnets. Can solve both Linear and nonlinear materials. Eddy Current Solver Solves sinusoidally-varying magnetic fields in frequency domain. Solves only for linear materials in 3D. Considers displacement currents. Induced fields such as skin and current proximity effects are also considered. Transient Magnetic Solves Transient magnetic fields caused by time-varying or moving electrical sources and permanent magnets in Linear or Non-linear materials. Induced fields such as skin and current proximity effects are considered. 47

48 Maxwell v17.0 Updates

49 Time Decomposition Method (TDM) New method: domain decomposition along time-axis allows to solve all time steps simultaneously instead of sequentially t0 t1 t2 t3 t4 t_end using either: a single box multiple boxes a cluster a Virtual Private Cloud 49

50 Non Linear Material in Eddy Current Saturable materials can be used in the Eddy current solver: Enter BH curve the same way as in Transient solver Maxwell will iterate the determine the equivalent operating point 50

51 Winding Support Eddy Current Solvers Winding setup is the same as transient except additional phase input New Winding Definition 51

52 Harmonic Stress Coupling With Maxwell eddy current solver 52

53 Coupled CFD Material Property Updates CFD can call on the fly Maxwell and update element by element permeability or conductivity Applications: advanced induction heating, liquid steel stirring Crucible Coils Outlet Level of conductive liquid from ANSYS Fluent losses computed by ANSYS Maxwell 53

54 Multiphysics Capabilities (*) Enable Electric Arc simulations or advanced Induction Heating simulations 54

55 Maxwell Demo Induction Heating Coil

56 Maxwell Demo Start with reverse engineered geometry from SpaceClaim. Add coil geometry in DesignModeler 56

57 Maxwell Demo Add a Maxwell 3D model to project and drag geometry onto it. Open geometry in Maxwell3D and draw a Region for air domain Coils must terminate on surface of domain Use offset o 0 in Z direction 57

58 Maxwell Demo Assign material properties to bodies Coil Copper Gear Steel_stainless 58

59 Maxwell Demo Define analysis type: Eddy current 59

60 Maxwell Demo Assign current excitations to coil face on surface Use a variable amps for current Automatically asks for definition of variable if not already defined 60

61 Maxwell Demo Assign current excitations to second coil face on surface Use same variable amps for current. Reverse direction 61

62 Maxwell Demo Add a Solution Setup. In solution setup we specify the convergence tolerance on the adaptive meshing No manual meshing required 62

63 Maxwell Demo Solution setup Specify the frequency to solve for. Can use a frequency range if desired Can use HPC to solve all frequencies in range simultaneously 63

64 Maxwell Demo Solution converges after 3 adaptive mesh refinements. Note: Stainless steel is non-magnetic (Permeability of 1.) therefore the skin depth is relatively large so a relatively coarse mesh can be used thus the solution converges in just a few adaptive remeshes. 64

65 Maxwell Demo Mesh for final adaptive pass 65

66 Maxwell Demo B field 66

67 Maxwell Demo Ohmic Losses (W/m3) 67

68 Maxwell Demo Maxwell losses transferred to Mechanical or Fluent by a simple drag and drop in Workbench 68

69 What About ANSYS EMAG? EMAG was the sole low frequency tool of ANSYS before the acquisition of Ansoft in Development efforts for EMAG were limited in recent years. Maxwell is the go-forward low-frequency electromagnetic tool All new R&D efforts for low-frequency electromagnetics are done in Maxwell. Maxwell is more efficient and is easier to use than EMAG and is now fully integrated in Workbench. 69

70 Conjugate Heat Transfer using ANSYS Fluent Mike Kuron

71 Fluent Demo Overview Conjugate Heat Transfer analysis with ANSYS Fluent Induction heat generation loads imported from Maxwell Predict transient temperature field with natural convection New overset meshing method in Fluent Updated Fluent GUI New Report Definitions for solution monitoring and post-processing 71

72 Overset Meshing Overset meshing connects overlapping mesh regions through interpolation, enabling: Part swapping Structured, flow aligned meshes around individual parts Moving mesh without remeshing or smoothing (Beta) 72

73 Overset Meshing An overset interface needs to contain: At least one background & one component mesh Each component mesh needs to have an overset BC Connectivity between meshes is established when the flow is initialized Dead cells : cells that fall outside of the domain Solve cells : where flow equations are solved Donor cells : subset of solve cells, sending data to: Receptor cells : cells receiving interpolated data Component mesh Overset BC Wall BC s Background mesh Solve cells (including Donors) 73

74 Overset Meshing ANSYS Mesher Background mesh: Gear + Surrounding Flow Domain Component mesh: Coil + Internal Flow + External Flow Conformal meshes within both the background and component domains 74

75 Overset Meshing ANSYS Mesher Named selections for overset mesh Identify overset BC location New capped faces with section planes Easier to visualize than hollowed out parts Can be activated/deactivated in the Section Planes menu 75

76 Updated Fluent Ribbon GUI New ribbon GUI similar to SpaceClaim. Replaces pull down menus. Work left to right, hitting all important analysis steps. Outline tree still available 76

77 Overset Meshing Overset setup procedure Each domain has been meshed individually Overset boundaries have been designated using named selections 77

78 Overset Meshing Overset setup procedure Overset mesh gets created upon solution initialization Background and Component Meshes Overset Mesh Solve Cells 78

79 Maxwell Volumetric Load Mapping Volumetric heat generation rates computed by Maxwell are mapped onto the Fluent model 79

80 Report Definitions New report definitions for solution monitoring Easier to plot and write data during run time Set up multiple monitors in one place 80

81 Induction Heating Results Transient Temperature field Report definitions enable streamlined solution monitoring of the transient induction coil heat up 81

82 Summary First release of the overset mesh method in an on-going development effort. Currently supports the following physics: Steady and transient (fixed mesh), 3D and 2D planar Pressure Based coupled solver Incompressible density method Single-phase or VOF multiphase Heat transfer k-epsilon and SST k-ω turbulence models BETA: moving mesh, compressible flow, VOF with surface tension, pressurefar-field BC, Workbench support, Pressure-Based segregated algorithms Drag and drop Fluent solution cell to a Mechanical Analysis System to transfer temperatures. 82

83 Structural Analysis using ANSYS Mechanical Pat Cunningham

84 Structural Analysis of the Gear 1. Add the remaining components the gear/shaft assembly. 2. Map the CFD temperatures onto the gear body. 3. Define the load step history of the assembly: Heat up the gear Move the shaft into the gear bore Cool the gear Move in the resisting gear into position Apply a torque the shaft. 84

85 Mechanical Demo Add to the geometry the shaft and gear sections using SpaceClaim or DesignModeler. 85

86 Mechanical Demo Set the stiffness behavior of the shaft and the engaging gear. 86

87 Mechanical Demo Define frictional contact between the gear and shaft and the two gears. Note: Asymmetric contact with the contact elements on the flexible body (main gear) is required. 87

88 Mechanical Demo Define a cylindrical body to ground joint on the shaft. Cylindrical is used so that we can insert the shaft into the heated gear and then apply a torque. 88

89 Mechanical Demo A translational joint is used to move the rigid gear section into place after the main gear has cooled. 89

90 Mechanical Demo The gear mesh consists of a brick mesh with inflation layers transitioning to a tet mesh with refinement in the gear contact region. 90

91 Mechanical Demo A remote displacement is used to constrain against rigid body motion before the shaft and gear are in contact. The remote displacement is assigned to a Remote Point attach to the main gear with a deformable connection to allow for free thermal growth. The remote displacement is deactivated when the gear is cooled and contacts the shaft. 91

92 Mechanical Demo A cylindrical joint limits the shaft to axial and rotational degrees of freedom. Joint loads are used to insert the shaft into the heated gear and apply a torque after it has returned to the reference temperature. 92

93 Mechanical Demo A translational body to ground joint moves the engagement gear rigid body into contact with the main. This joint resists the moment applied to the shaft cylindrical joint through the contact region between the two gears.. 93

94 Mechanical Demo Temperatures from the conjugate CFD analysis are mapped onto to the gear body in the first load step. The temperature load is deactivated after the shaft is inserted into the expanded gear. 94

95 Mechanical Demo The contact tracker is used to monitor progress as the gear is thermal expansion is removed. Note: Contact Trackers at v17 can be added and modified while the solution is ongoing. 95

96 Fatigue Simulation Mike Bak

97 Fatigue Tool Capabilities The Fatigue Tool provides fatigue life prediction capability within Mechanical. Now included with Mechanical Enterprise license. The main features include: Stress life (high cycle fatigue) and strain life (low cycle fatigue) approaches. Fatigue data defined in Engineering Data. Mean stress theory to account for non-zero mean stress cyclic loading. Constant amplitude, history data, or non-proportional loading. 97

98 Procedure for Gear Shaft Fatigue In the current demonstration of the gear shaft, the following assumptions are used for the fatigue calculation: The cyclic stress occurs once per revolution: A point on the gear sees the maximum stress state near the gear contact location with the mating gear (load step 4 results). As it travels to the opposite side, the stress state is assumed to be equal to the residual stress state (load step 3 results). Min Max 98

99 Procedure for Gear Shaft Fatigue The fatigue tool allows for three different types of cyclic loading: Constant amplitude. User identifies one result step that defines the maximum condition in the cyclic loading. User defines the R-ratio for this loading that defines the ratio of the minimum stress divided by the maximum stress. A fully-reversed loading is an R-ratio of -1. History data. User supplies an external file that contains a series of scale factors that are used to scale one load set to define a complex load history. The fatigue calculation will extract the cyclic information using rainflow calculations. Non-proportional loading. The user specifies two load sets that represent the minimum and maximum load conditions. This approach is used in this application to define the cyclic loading. 99

100 Procedure for Gear Shaft Fatigue Strain life fatigue behavior used. Using Workbench structural steel built-in strain life data. 100

101 Procedure for Gear Shaft Fatigue Stress life fatigue models high cycle fatigue. Assumes stresses below yield stress. Cycles from 100,000 to millions of cycles before failure. Defined using S-N data (stress range vs. cycles to failure). 101

102 Procedure for Gear Shaft Fatigue Strain life fatigue models both low cycle and high cycle fatigue. Assumes that localized behavior could include plastic strains. A plot of the strain range versus cycles is a combination of the elastic and plastic portions of the response. Strain life also needs information on the cyclic hysteresis behavior, defined using the cyclic stress-strain data. Strain life curve Cyclic stress strain behavior 102

103 Procedure for Gear Shaft Fatigue The cyclic loading is defined by two load steps. The maximum cyclic load condition is the applied torque response in Load Step 4. The minimum cyclic load condition is the residual stress state in Load Step 3. Two separate load conditions can be used to define the cyclic load using the non-proportional loading type. First, add a Solution Combination. Define the results from Load Steps 3 and 4 within the Solution Combination Worksheet. 103

104 Procedure for Gear Shaft Fatigue Add the Fatigue Tool under the Solution Combination. Assign the Analysis Type = Strain Life Assign the Loading Type = Non-Proportional 104

105 Procedure for Gear Shaft Fatigue Additional fatigue settings: Fatigue Strength Factor: A reduction factor used to adjust for a real world environment for surface finish, fatigue data scatter, smaller probability of failure, etc. Will use a factor of Mean Stress Theory: Typical fatigue data is generated under fully-reversed loading (i.e. mean stress = 0). This situation is rarely encountered in real world problems. The mean stress theory will adjust the strain amplitude in the cyclic loading to account for non-zero mean stress. Will use the Morrow option. 105

106 Procedure for Gear Shaft Fatigue Insert Life under the Fatigue Tool. Scope to the critical region of the gear (ignore gear tooth region). The fatigue life contour shows a minimum life of 13,411,000 cycles. At 100 RPM, and assuming continual operation, the predicted fatigue life is 2235 hours of operation. 106

107 Fatigue Summary Fatigue analysis predicts the life of a structure under cycle loading conditions. The Fatigue Tool in ANSYS Mechanical performs fatigue analysis using Stress Life or Strain Life approaches. Now included in the ANSYS Mechanical Enterprise licensing. Various cyclic load definitions are available: Constant amplitude History data Non-proportional Additional fatigue settings are available. Fatigue data defined in Engineering Data. 107

108 Fracture Simulation Mike Bak

109 New Fracture Enhancements in V17.0 The following fracture enhancements are available in Release 17.0: Arbitrary cracks: Previously, could model a semi-elliptical crack, or a pre-meshed crack. Arbitrary cracks can be planar or non-planar arbitrary shapes. Use a surface body to define the crack surface. Meshed with tetrahedron elements. Supported by Static Structural and Transient Structural analyses. Support SIFS, J-Integral, VCCT, Material Force, T-Stress, and C*-Integral fracture parameters. Tetrahedron crack meshes are now supported for all crack types. Material Force, T-Stress and C*-Integral fracture parameters are now available for all crack definitions. 109

110 Procedure for Gear Shaft Fracture In the current demonstration of the gear shaft, the following assumptions are used for the fracture analysis: An arbitrary crack on the inside surface of a hole is modeled using a Static Structural analysis. Since a finer mesh in the crack vicinity is required, submodeling technique is used to isolate the crack region. Boundary conditions on the cut boundaries are taken from the full gear shaft analysis using the automated submodeling technique. The stress intensity factor distribution along the crack front is sought. Can compare to the material fracture toughness to determine if the crack will propagate due to the static loading. The fracture toughness is assumed to be equal to 180 ksi-in 1/2. 110

111 Procedure for Gear Shaft Fracture The procedure for the fracture analysis using the following steps: On the Project Page: Duplicate the Static Structural analysis of the gear shaft to create the submodel analysis. Connect the original model Solution to the submodel Setup. In DesignModeler: Add a surface body that defines the arbitrary crack. Slice the model to obtain the submodel region. Suppress all geometry outside of the submodel region. 111

112 Procedure for Gear Shaft Fracture The submodeling procedure in Mechanical: Under the Imported Load (from connecting to the full model), insert a Cut Boundary Condition. Set the Source Time = 3 s (residual stress state). Scope to the three surfaces of the cut boundaries. Generate to obtain the submodeling boundary conditions. Temperature mapping is not required since the submodel is using the residual condition load step in which the gear has cooled. 112

113 Procedure for Gear Shaft Fracture Solving without a crack, the submodel solution should predict similar results to the global model: Global Principal Stress Submodel Principal Stress 113

114 Procedure for Gear Shaft Fracture Of interest is the direction of the maximum principal stress: Note that an existing crack in the hole will tend to propagate perpendicular to the maximum principal stress direction. 114

115 Procedure for Gear Shaft Fracture The crack procedure in Mechanical: Under Geometry of the Surface Body, change the Behavior to Construction Body. This indicates to Mechanical that this body is not a structural body to be meshed and analyzed, but will be used to define the crack. Generate the base mesh. Must be a tetrahedron mesh in the crack region. Don t need to mesh the crack region differently this will be done during fracture meshing. 115

116 Procedure for Gear Shaft Fracture The crack procedure in Mechanical: Under Model, insert Fracture. Under Fracture, insert an Arbitrary Crack. Scope crack to the gear solid body. Change the Coordinate System to the local crack system (X-axis must point inward toward crack). Identify the Surface Body to define the crack. Set Largest Contour Radius to 0.05 in. Generate the fracture crack. 116

117 Procedure for Gear Shaft Fracture Fracture mesh included in base tetrahedron mesh. 117

118 Procedure for Gear Shaft Fracture Run analysis: Apply any other boundary conditions or loading (reapply frictionless support). Include submodeling cut boundary conditions. Generate the solution. Post-process the fracture analysis: Insert Fracture under Solution, and insert SIFS Result under Fracture. Select the arbitrary crack. Generate the stress intensity factor distribution along the crack front. 118

119 Procedure for Gear Shaft Fracture The stress intensity factor distribution is calculated at six continually larger contours about the crack front. The results should converge within a few contours. Contour plot of the 6 th contour is shown. Plot of all contour solutions is also shown. Maximum value of 12.5 ksi-in 1/2 is much less than the fracture toughness of 180 ksi-in 1/2, so this crack would not be predicted to propagate under the given loading. 119

120 Fracture Summary ANSYS Mechanical has updated its fracture capability in V17.0 to include an arbitrary crack definition. Like the planar semi-elliptical crack, the crack is not defined in the CAD geometry, and the initial mesh does not include the crack. The arbitrary crack can be planar or non-planar, and is defined using a Surface Body. The fracture procedure will automatically insert the defined crack into the uncracked body, performing the local meshing based on supplied settings. The distribution of the stress intensity factor along the crack front can be obtained from the Fracture Tool under Solution. Fatigue crack propagation analysis could be performed to determine if and how the crack would grow in the cyclic loading environment. Will address this type of analysis procedure using XFEM in a later presentation. 120