TURBINE ENGINE LIFE MANAGEMENT App. N AIAA AIRCRAFT ENGINE DESIGN

Transcription

1 CORSO DI LAUREA SPECIALISTICA IN Ingegneria Aerospaziale PROPULSIONE AEROSPAZIALE I TURBINE ENGINE LIFE MANAGEMENT App. N AIAA AIRCRAFT ENGINE DESIGN LA DISPENSA E DISPONIBILE SU Prof. Ing. A. Ficarella antonio.ficarella@unile.it 1

2 LIFING ( LIFE -ING 2

3 the most notable advances in the shaded area finite element modeling in stress analysis improved materials engine controls testing techniques manufacturing and inspection surface treatments beneficial residual stresses Laser peening is the process of hardening or peening metal using a powerful laser. Laser peening can impart a layer of residual compressive stress on a surface that is four times deeper than that attainable from conventional shot peening treatments."[1] Laser peening is often used to improve the fatigue resistance of highly stressed critical turbine engine components, and the laser (or component) is typically manipulated by an industrial robot. data recording systems usage tracking systems 3

4 LESSONS LEARNED it is dangerous to assume defect-free structure critical parts and failure modes must be identified thermal and vibratory environments must be identified analytic stresses must be verified by testing materials and processes must be adequately characterized stress spectra must be based on the service usage design, test potential airframe/engine structural interactions closed-loop management procedures 4

5 LIFE MANAGEMENT SCOPE high-energy rotating and pressurized components maximize the use of the parts to minimize costs 5

6 the max stress range is used to enter the low cycle fatigue (LCF) min life material curve at the corresponding operating temperature to give the component min life 6

7 more rigorous thermal, stress and fatigue and fracture analysis 7

8 DAMAGE TOLERANT APPROACH the damage is present at all location and should not grove to critical size FRACTURE CRITICAL COMPONENTS whose failure would result in loss of sustained flight all major rotating structures DURABILITY CRITICAL COMPONENTS could cause significant engine damage HOT PARTS the life requirement is one-half that of cold parts COLD PARTS INITIAL FLAW DIMENSION nondestructive evaluation (NDE) RESIDUAL STRENGTH load carrying capability considering the presence of damage and accounting for the growth of the damage 8

9 INSPECTION INTERVAL FLIGHT DATA RECORDER ENGINE LIFE RECORDER CREEP deformation LOW CYCLE FATIGUE (LCF) HIGH CYCLE FATIGUE (HCF) STRESS RUPTURE LASER SHOCK PEENING L(SP) to desensitize airfoil leading edges to foreign object damage (FOD) 9

10 CRACK INITIATION LIFE component life based on the attainment of in. crack CRACK PROPAGATION LIFE life where a rack from an initial flaw size grows to a critical size (failure) 10

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12 LIFTING CONCEPTS a 150-h test was the main pass of fail criteria used to qualify a new engine design SAFE LIFE CRITERION the LCF limit exceed the required usage interval life limit usually based on min or -3 value of the material life property curve for crack initiation all like components be removed even though the components may have 10 times more life remaining 12

13 SAFETY LIFE PLUS DAMAGE TOLERANCE economically provide max product safety 13

14 successful application - supporting technologies nondestructive inspections mechanical testing structural analysis mission profile cycle tracking extensive material testing 14

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16 RETIREMENT-FOR-CAUSE retired from service when it had incurred quantifiable damage upon the ability of NDE to detect the initial flaw 16

17 INSPECTION AND POD POD = probability of detection 90% POD at 95% confidence level (CL) for initial flaw size 17

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19 FLUORESCENT PENETRANT INSPECTION small discontinuities surface defects 19

20 EDDY CURRENT INSPECTION when electrically conductive materials is exposed to an alternating magnetic field, eddy current are induced on the material surface the effect of eddy current, generating magnetic fields that interact with the magnetic fields of the transducer, can me measured used to detect surface discontinuities 20

21 can detect both surface and subsurface discontinuities can be used on ferrous and non-ferrous material more versatile than fluorescent penetrant adjustable sensitivity portable limited to electrically conductive materials reference standards and operators training difficulty in interpreting results 21

22 ULTRASONIC INSPECTION thickness check billet/forge inspection for internal defects weld examination surface defects composite inspection for delamination and porosity 22

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24 ENGINE STRUCTURAL DEVELOPMENT PLAN 24

25 DEVELOPMENT AND QUALIFICATION TESTING 150-h formal qualification test not mission oriented appreciable time at high power to ferret out hightemp creep and stress rupture some partial-throttle transient too few to drive a low cycle fatigue 25

26 ATM accelerated mission testing (Military) all the nondamaging cycles and level removed 26

27 severity analysis tools 27

28 to balance the severity of an ATM cycle by adjusting the magnitude of transients and hold time to control thermally induced stresses 28

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30 component special testing turbine/compressor over-speed 115% disk 122% max speed overtemperature 1st stage turbine 81 F 30

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32 1000 Simulated Service Cycle ( C cycle) Test (Commercial) 32