Residual Stress Modeling in Machining Presented by by Jiann-Cherng - PowerPoint PPT Presentation

Residual Stress Modeling in Machining Presented by by Jiann-Cherng Su And Dr. Steven Liang George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology 1

Outline � Motivation � Proposed Modeling Method – Force modeling – Temperature modeling – Residual stress modeling � Questions? 2

Motivation � Residual stress affects fatigue life � Residual stress affects corrosion crack resistance � Residual stress affects part distortion � Machining induces residual stress 3

Physics-Based Modeling Plan Process Conditions Process Conditions Process Conditions Process Conditions •Speed, Feed, Depth of Cut •Speed, Feed, Depth of Cut •Speed, Feed, Depth of Cut •Speed, Feed, Depth of Cut •Cutting Tool Geometry •Cutting Tool Geometry •Cutting Tool Geometry •Cutting Tool Geometry •Workpiece Material Properties •Workpiece Material Properties •Workpiece Material Properties •Workpiece Material Properties Cutting Force Modeling Cutting Force Modeling Cutting Force Modeling Cutting Force Modeling Temperature Modeling Temperature Modeling Temperature Modeling Temperature Modeling •Chip Formation Force (Oxley) •Chip Formation Force (Oxley) •Chip Formation Force (Oxley) •Chip Formation Force (Oxley) •Moving Heat Source •Moving Heat Source •Moving Heat Source •Moving Heat Source •Ploughing Force (Waldorf, Smithey) •Ploughing Force (Waldorf, Smithey) •Ploughing Force (Waldorf, Smithey) •Ploughing Force (Waldorf, Smithey) •Stationary Heat Source •Stationary Heat Source •Stationary Heat Source •Stationary Heat Source •Tool Geometry (Huang) •Tool Geometry (Huang) •Tool Geometry (Huang) •Tool Geometry (Huang) •Experiment/Validation •Experiment/Validation •Experiment/Validation •Experiment/Validation � Experiments/Validation � Experiments/Validation 1 � Experiments/Validation � Experiments/Validation 1 Cutting Cutting Workpiece Workpiece Cutting Cutting Workpiece Workpiece Forces Forces Temperature Temperature Forces Forces Temperature Temperature Residual Stress Modeling Residual Stress Modeling Residual Stress Modeling Residual Stress Modeling • Rolling/Sliding Contact • Rolling/Sliding Contact • Rolling/Sliding Contact • Rolling/Sliding Contact • Stress Fields • Stress Fields • Stress Fields • Stress Fields • Incremental Plasticity Equations • Incremental Plasticity Equations • Incremental Plasticity Equations • Incremental Plasticity Equations • Coordinate Transformations • Coordinate Transformations • Coordinate Transformations • Coordinate Transformations • X-Ray Measurements • X-Ray Measurements • X-Ray Measurements • X-Ray Measurements • Experiment/Validation • Experiment/Validation • Experiment/Validation • Experiment/Validation 4

Predicting Cutting Forces � Sources of Cutting Forces – Chip formation forces – Ploughing forces � Classical Models Based on Orthogonal/Oblique Machining � Geometric Considerations for Non-Orthogonal Processes – Side rake angle – Back rake angle – Tool edge radius – Tool nose radius 5

Predicting Cutting Forces � Cutting Forces for Orthgonal Machining Cutting Conditions Cutting Conditions Cutting Conditions Cutting Conditions Rake angle, Cutting speed, Depth of cut, Rake angle, Cutting speed, Depth of cut, Rake angle, Cutting speed, Depth of cut, Rake angle, Cutting speed, Depth of cut, Width of Cut, Material Properties Width of Cut, Material Properties Width of Cut, Material Properties Width of Cut, Material Properties Initial Value for Shear Angle (φ) Initial Value for Shear Angle (φ) Initial Value for Shear Angle (φ) Initial Value for Shear Angle (φ) Oxley’s Cutting Force Model Oxley’s Cutting Force Model Oxley’s Cutting Force Model Oxley’s Cutting Force Model • Iterate to find T AB • Iterate to find T AB • Iterate to find T AB • Iterate to find T AB • tan θ =1+2( π /4- φ )-Cn, λ = θ - φ + α • tan θ =1+2( π /4- φ )-Cn, λ = θ - φ + α • tan θ =1+2( π /4- φ )-Cn, λ = θ - φ + α • tan θ =1+2( π /4- φ )-Cn, λ = θ - φ + α • R=F s /cos θ , F=Rsin λ , N=Rcos λ , F c =Rcos( λ−α ) • R=F s /cos θ , F=Rsin λ , N=Rcos λ , F c =Rcos( λ−α ) • R=F s /cos θ , F=Rsin λ , N=Rcos λ , F c =Rcos( λ−α ) • R=F s /cos θ , F=Rsin λ , N=Rcos λ , F c =Rcos( λ−α ) φ = φ + 0.1 o φ = φ + 0.1 o φ = φ + 0.1 o φ = φ + 0.1 o • Iterate to find T chip • Iterate to find T chip • Iterate to find T chip • Iterate to find T chip • k AB , τ int , k int • k AB , τ int , k int • k AB , τ int , k int • k AB , τ int , k int No No τ int = k int ? τ int = k int ? τ int = k int ? τ int = k int ? Yes Yes φ, k AB , F C , F T φ, k AB , F C , F T φ, k AB , F C , F T φ, k AB , F C , F T End End End End 6

Predicting Cutting Forces � Geometric Transformation for Tool Nose Radius (Wang & Mathew) � Equivalent oblique transformation = α + α * * F K A cos K A sin cs n c n f c n = α − α * * F K A cos K A sin ts f c n n c n ( ) − α η − α η * * * * * * F sin i cos i sin tan F cos tan = cs n c ts n c F α η + R * * * * sin i sin tan cos i n c � Force components for non-zero side cutting angle = P F 1 cs = + P F cos C F sin C 2 ts S R S = − P F sin C F cos C 3 ts S R S 7

Ploughing Force Prediction � Ploughing Effects – Force contribution due to cutting edge roundness – Produces a size effect � Slip-line field modeling (Waldorf 1999) ( ) ( ) ⎡ η φ − γ + η + ⎤ cos 2 cos = ⋅ ⋅ ⎢ P k w ⎥ CA ( ( ) ) ( ) + θ + γ + η φ − γ + η cut ⎦ ⎣ 1 2 2 sin 2 sin ( ) ( ) ⎡ − η φ − γ + η + ⎤ cos 2 sin = ⋅ ⋅ ⎢ P k w ) CA ⎥ ( ( ) ) ( + θ + γ + η φ − γ + η thrust ⎦ ⎣ 1 2 2 sin 2 cos δ = CA ( ) η sin 8

Research Plan Process Conditions Process Conditions Process Conditions Process Conditions •Speed, Feed, Depth of Cut •Speed, Feed, Depth of Cut •Speed, Feed, Depth of Cut •Speed, Feed, Depth of Cut •Cutting Tool Geometry •Cutting Tool Geometry •Cutting Tool Geometry •Cutting Tool Geometry •Workpiece Material Properties •Workpiece Material Properties •Workpiece Material Properties •Workpiece Material Properties Cutting Force Modeling Cutting Force Modeling Cutting Force Modeling Cutting Force Modeling Temperature Modeling Temperature Modeling Temperature Modeling Temperature Modeling •Chip Formation Force (Oxley) •Chip Formation Force (Oxley) •Chip Formation Force (Oxley) •Chip Formation Force (Oxley) •Moving Heat Source •Moving Heat Source •Moving Heat Source •Moving Heat Source •Ploughing Force (Waldorf, Smithey) •Ploughing Force (Waldorf, Smithey) •Ploughing Force (Waldorf, Smithey) •Ploughing Force (Waldorf, Smithey) •Stationary Heat Source •Stationary Heat Source •Stationary Heat Source •Stationary Heat Source •Tool Geometry (Huang) •Tool Geometry (Huang) •Tool Geometry (Huang) •Tool Geometry (Huang) •Experiment/Validation •Experiment/Validation •Experiment/Validation •Experiment/Validation 2 � Experiments/Validation � Experiments/Validation 1 2 � Experiments/Validation � Experiments/Validation 1 Cutting Cutting Workpiece Workpiece Cutting Cutting Workpiece Workpiece Forces Forces Temperature Temperature Forces Forces Temperature Temperature Residual Stress Modeling Residual Stress Modeling Residual Stress Modeling Residual Stress Modeling • Rolling/Sliding Contact • Rolling/Sliding Contact • Rolling/Sliding Contact • Rolling/Sliding Contact • Stress Fields • Stress Fields • Stress Fields • Stress Fields • Incremental Plasticity Equations • Incremental Plasticity Equations • Incremental Plasticity Equations • Incremental Plasticity Equations • Coordinate Transformations • Coordinate Transformations • Coordinate Transformations • Coordinate Transformations • X-Ray Measurements • X-Ray Measurements • X-Ray Measurements • X-Ray Measurements • Experiment/Validation • Experiment/Validation • Experiment/Validation • Experiment/Validation 9

Thermal Modeling � Thermal Effects – Thermal strain – Material properties – Potential phase change � Sources of Heat – Shear zone – Tool edge rubbing � Previous Research – Jaeger’s moving heat source – Komanduri metal cutting modeling 10