AC 33.70-5 APPENDIX A. MA NUFACTURING-INDUCED ANOMALY CALIBRATION TEST CASE FOR
AXIAL BLADE SLOTS A.1 Introduction.
A.1.1 Purpose of the Test Case.
This appendix provides instructions for calibrating a probabilistic risk assessment methodology for manufacturing-induced anomalies in axial blade attachment slots. This includes damage associated with blade insertion and removal during assembly and overhaul. It does not specifically include damage in terms of size or frequency unique to the service operation of the engine.
A.1.2 Scope of Input Data.
This appendix includes all the input data required to complete the test case, such as analysis guidelines, component geometry, boundary conditions, material property data, and inspection efficacy. The input data should be used to compute the POF of a feature within the defined cyclic life interval. An applicant must demonstrate the acceptability of their probabilistic process by meeting the POF criteria defined in table A-8.
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AC 33.70-5 A.2 Test Case Input Data.
A.2.1 Problem Description and Geometry.
The test case geometry, shown in figure A-1, consists of two components: a turbine disk and a blade. Both parts are made from a nickel-based superalloy, with the blade assumed to be solid and isotropic. The blade applies centripetal forces to the disk, but no aerodynamic or pressure loads are applied. In the finite element analysis, the blade should be constrained to prevent axial movement out of the attachment slot.
Figure A-1. Representation of Test Case Blade and Disk Geometry A–2
Figure A-2. Test Case Geometry Definition: Isometric View of 5 Degree Sector Showing Disk and Blade AC 33.70-5 A.2.2 Test Case G eometry Details.
An isometric view and drawings of the disk and blade are shown in figures A-2 through A-8. Dimensions are provided in both Imperial and International System of Units (SI units). The disk features a two-lobe firtree, with 72 equally spaced slots.
A.2.2.1 Figure A-2 provides an isometric view of a 5-degree sector of the test case geometry, showing the disk and blade for the component under assessment.
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AC 33.70-5 A.2.2.2 Figure A-3 provides an axisymmetric profile view of the disk, with dimensions specified in both inches and millimeters.
1.000 -(25.40) 51*22 - 72 SLOTS EQ SP
- 93) ฿18.000
(457.20) @16.300 _R .250
(414.02) (6.34)
•0"13'9" 305
(7.75) ฿12.055
(306.20) . 250
(6.35 ) R 2.000 (50,80) ฿5.994
(152.25) #3.996
1.500 (101.50)
(38.10)
ALL DIM APPLY BOTH SIDES UOS Figure A-3. Test Case Geometry Definition: Disk Axisymmetric Profile in Inches and (Millimeters) A-4
AC 33.70-5 A.2.2.3 Figure A-4 shows a radially inward view of the test case geometry, highlighting an 8-degree broach angle. This view provides critical details of the angular orientation, ensuring a precise understanding of the broaching direction for axial blade slot geometry shown in figure A-5.
Figure A-4. Test Case Geometry Definition: View Looking Radially Inward Showing 8.0 Degree Broach Angle A–5
AC 33.70-5 A.2.2.4 Figure A-5 presents the A -A view of the disk broach slot profile, displaying key dimensions in inches and millimeters.
Figure A-5. Test Case Geometry Definition: View A-A of Disk Broach Slot Profile in Inches and (Millimeters) Not to Scale A–6
AC 33.70-5 A.2.2.5 Figure A-6 illustrates the axisymmetric view of the blade, providing key height and width dimensions in inches and millimeters.
Figure A-6. Test Case Geometry Definition: Axisymmetric View of Blade Showing Height and Width in Inches and (Millimeters) A–7
AC 33.70-5 A.2.2.6 Figure A-7 provides a radially inward view of the blade, illustrating the broach angle and blade thickness in inches and millimeters.
Figure A-7. Test Case Geometry Definition: View of Blade Looking Radially Inward Showing Broach Angle and Blade Thickness in Inches and (Millimeters) A–8
AC 33.70-5 A.2.2.7 Figure A-8 displays the blade attachment profile (View B -B), illustrating the dimensions in both inches and millimeters.
Figure A-8. Test Case Geometry Definition: View B-B Showing Blade Attachment Profile in Inches and (Millimeters) Not to Scale A–9
AC 33.70-5 A.2.3 Mission Profile Definition.
The stresses and corresponding life capability at the disk's slot bottom are primarily driven by the disk's rotational speed but also from the rotor thermal gradient. This test case simulates multiple phases of a typical commercial revenue service operation, capturing changes in disk rotational speed and rotor stress due to thermal contributions through the mission profile. The mission profile is defined by 11 unique time points. A time and disk speed history profile defining these mission points is shown in figure A-9 and table A-1.
Test Case Mission Speed Profile Test Case Mission Temperature Profile 14000 1200 1100 • 600 12000 1000 - 550 900 - 500 Temperature (deg F) 800 - 450 8000 700 Disk Spee 6000 400 4000 300 2000 200 •Disk Slot Bottom 100 *Disk Bore 2000 4000 6000 8000 10000 12000 14000 1600 5000 10000 15000 Mission Time (sec) Mission Time (sec) Figure A-9. Disk Speed and Temperature over Test Case Flight Profile Table A-1. Tabulated Disk Speeds and Temperatures for Test Case Flight Profile Disk Bore Disk Slot Bottom Disk Bore Disk Slot Bottom Rotational Time Temperature Temperature Temperature Temperature Speed Radius = 2.0 in Radius = 8.38 in Radius = 50.8 mm Radius = 212.77 mm sec deg F deg F deg C deg C RPM
42.8 42.8 6.0 6.0 0.0 18 42.8 42.8 6.0 6.0 2708.8 60 64.4 120.2 18.0 49.0 9029.5 608 73.4 208.2 23.0 97.9 9211.1 642 446.0 1,112.0 230.0 600.0 9504.1 1689 975.2 1,050.8 524.0 566.0 12512.6 2008 1,014.8 987.8 546.0 531.0 12182.3 4127 807.8 892.2 431.0 477.9 12158.6 14127 807.8 892.2 431.0 477.9 12046.4 14517 807.8 426.7 431.0 219.3 12042.0 15947 334.4 392.0 168.0 200.0 0.0 A-10
AC 33.70-5 A.2.4 Thermal Gradients and Mission Points.
A unique linear radial thermal gradient is used for each mission point. Temperatures at two different radial points (disk bore and slot bottom) are provided as a reference;
temperatures at all other radial stations vary linearly, proportional to the radius of interest. No axial or circumferential thermal gradients are assumed. An example of this radial temperature gradient is shown in figure A-10 for time point t = 642 seconds.
Temperature 274 ¡Temperature min: 446.
max: 1332.5 min: 230.
Note: 249 max: 722.51 1350.
1250. Contour plot to the left shows 732.22 1150. dimensions in inches and 224 676.67 X2 1050. 621.11
950. temperatures in degrees 565.56
850. Fahrenheit. 510.
750. 454.44
550. 650. Contour plot to the right shows 174.. 398.89 343.33
450. dimensions in millimeters and 287.78 1350. temperatures in degrees Celsius 232.22 149 176.67 (Tz-T1) T(x)= (×-×1) +T1 _124 (×2-×1) 30 Figure A-10. Example of Test Case Linear Thermal Gradient at t-642s A-11
AC 33.70-5 A.2.5 Material and Crack Growth Data.
A.2.5.1 Material Properties Overview.
The stress analysis for this test case requires material properties for the disk and blade.
Both components use the same alloy. Relevant material properties include Young’s modulus of elasticity (E), material density (ρ), coefficient of thermal expansion (α), and Poisson’s ratio (ν). Except for density, all properties vary with temperature. The reference temperature for zero thermal expansion is 68°F (20°C). See table A-2.
Table A-2. Test Case Physical Material Properties A.2.5.2 Material Properties.
The material density is defined as 0.29 lbm/in3 (8027 kg/m3). These material properties are representative of a commonly used alloy, but they have been modified specifically for this test case. These properties should not be used for detailed engineering design or certification.
A.2.5.3 Cyclic Crack Growth Data.
In addition to the physical data, cyclic fatigue crack growth properties necessary for crack growth calculations are provided. The crack growth assessments are based solely on cyclic crack growth without considering time-dependent effects or load interactions. The crack growth rates per cycle, as a function of the change in stress intensity (da/dN vs dK), are given using temperature-dependent constants fitted in the form of the sigmoidal model shown in equation A-1. Applicants may convert the provided model into an equivalent format suitable for their own analysis tools, such as:
• Tabular Input
• Hyperbolic Sine
• Nasgro equation
• Simple Paris law (if cyclic threshold is not considered).
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