Evaluation of Mechanical Properties and Material Modeling for a Rocket Thrust Chamber

Transcription

1 IJSTE - Intenational Jounal of Science Technology & Engineeing Volume 3 Issue 02 August 2016 ISSN (online): X Evaluation of Mechanical Popeties and Mateial Modeling fo a Rocket Thust Chambe Reeba Jacob Gaduate Student Ma Baselios College of Engineeing Tivandum Jean Molly Simon Assistant Pofesso Ma Baselios College of Engineeing Tivandum A. K. Asaff Goup Diecto SDAG/LPSC/ISRO Tivandum Kishnajith Jayamani Enginee SDAG/LPSC/ISRO Tivandum Abstact High thust ocket engines ae employed in satellite launch vehicles deliveing heavy satellites and space-cafts. The thust chambe of such engines ae geneally of double walled constuction in which the inne wall is of a high conductivity high ductility mateial like a coppe alloy and oute wall of stainless steel. Duing engine opeation, the chambe will be subjected to themal and pessue loads. Due to sevee themal and pessue loads, inne wall opeates in the elasto-plastic condition. Repeated opeation of the engine will thus cause cyclic plastic defomations inducing low cycle fatigue. The thust chambe investigated is of double walled constuction in which fou metallic mateials ae used at diffeent zones: thee stainless steels (designated as 12X21H5T, 12X18H10T and 06X15H10T espectively which have vaying stength popeties) and a high conductivity coppe alloy which contains taces of Chomium, Ziconium and Titanium. A mateial chaacteization pogam is initiated to evaluate the monotonic tensile popeties of the above mateials at oom tempeatue, in a Univesal Testing Machine. This pape pesents the constitutive modeling of the above mateials followed by finite element modelling and themo stuctual analysis of the thust chambe. Keywods: ANSYS, Semi-Cyo, Thust Chambe, UTM, Stess Analysis I. INTRODUCTION The thust chambe consists of cylindical section whee combustion occus, a section naowing towads thoat, and a bell shaped, expanding nozzle section though which the combustion gases ae expelled. Regeneative cooling of the thust chambe is achieved by passing keosene though ectangula coolant passages milled to oute suface of the inne wall. The numbe of coolant passages vay along the length of the chambe.[1] The oute and inne walls ae attached togethe by bazing at high tempeatue in a vacuum funace. Fig.1 shows configuation of the thust chambe. Fig.2 shows a typical coss section of the same. Fig. 1: Configuation of the thust chambe [2] All ights eseved by 341

2 Fig. 2: Coss section of the thust chambe [2] II. EXPERIMENTAL INVESTIGATION Tension tests ae caied out at oom tempeatue in an INSTRON 8862 electomechanical UTM having a load ating of 100 kn. Defomation of the specimen is measued using an extensomete [3]. Both ound and flat specimens can be tested in the machine. The machine suppots testing at ambient and elevated tempeatues. The specimens ae fabicated and tested till failue as pe ASTM E-8 standads [7]. Tension Testing of 12X18H10T 12X18H10T is a medium stength stainless steel. Fig. 3 shows the engineeing stess stain gaph fo each specimen. Tension Testing of 12X21H5T 12X21H5T is a high stength stainless steel. This mateial can eadily be welded to both coppe alloy as well as 12X18H10T and hence is used as an intefacing mateial to join the inne wall coppe alloy to the 12X18H10T mateial inne wall in the divegent zone. Two flat specimens ae tested in this case and the coesponding engineeing stess stain gaphs ae shown in Fig.4. Tension Testing of 06X15H5MB 06X15H5MB is a special type high stength steel. Two ound specimens ae tested and the stess stain gaphs ae shown in Fig.5. Tension Testing of Coppe alloy using Smooth Round Specimens Two ound specimens ae tested and the coesponding stess stain gaphs ae shown in Fig.6. Fig. 3: Engineeing stess stain gaphs fo 12X18H10T Fig. 4: Engineeing stess stain gaphs fo 12X21H5T Fig. 5: Engineeing stess stain gaphs fo 06X15H5MB Fig. 6: Engineeing stess stain gaphs fo coppe alloy All ights eseved by 342

3 III. CONSTITUTIVE MODELLING Fom the engineeing stess-stain data, the tue stess-stain elationship is evaluated and the data expessed in the fom: (1) Whee, K = stength coefficient, n = stain hadening exponent. Tue stesses and stains beyond specimen necking ae calculated using the methodology outlined by Royland [5]. Mateial model used is the Multilinea Isotopic hadening (MISO) plasticity model available in ANSYS [2]. Constitutive modelling of 12X18H10T Table-1 shows stength coefficient and stain hadening exponent fitted to the tue stess-stain data fo the 3 specimens. Tue stess-stain gaphs ae shown in Fig.7. The mateial exhibited stain hadening beyond yielding. All the specimens showed nealy same behaviou. Constitutive modelling of 12X21H5T Table-2 shows stength coefficient and stain hadening exponent fo the specimens. Tue stess-stain gaphs ae shown in Fig.8. The mateial exhibited elastic-pefectly plastic behaviou. All the specimens showed same tend. Constitutive Modelling of 06X15H5MB Table-3 shows stength coefficient and stain hadening exponent fo the specimens. Tue stess-stain gaphs ae shown in Fig.9. The mateial exhibited elastic-pefectly plastic behaviou. All specimens showed simila tend. Constitutive Modelling of Coppe Alloy Table-4 shows stength coefficient and stain hadening exponent fo the specimens. Tue stess-stain gaphs ae shown in Fig. 10. The mateial exhibited stain hadening beyond yielding. All specimens showed simila behaviou. Table - 1 Results of tue stess stain modelling of 12X18H10T Specimen # Stength coefficient, K (MPa) Stain hadening exponent, n Table - 2 Results of tue stess stain modelling of 12X21H5T Specimen # Stength coefficient, K (MPa) Stain hadening exponent, n Table - 3 Results of tue stess stain modelling of 06X15H5MB Specimen # Stength coefficient, K (MPa) Stain hadening exponent, n Table - 4 Results of tue stess stain modelling of coppe alloy Specimen # Stength coefficient, K (MPa) Stain hadening exponent, n Fig. 7: Mateial model fo12x18h10t Fig. 8.Mateial model fo 12X21H5T Fig.9.Mateial model fo 06X15H5MB All ights eseved by 343

4 Fig. 10: Mateial model fo coppe alloy IV. STRESS ANALYSIS OF THRUST CHAMBER Stuctual behaviou of thust chambe is studied using axi-symmetic model by supplying Multilinea isotopic hadening mateial model paametes. Themal expansion secant coefficient and themal conductivity at diffeent tempeatues obtained fom liteatue ae given fo inne and oute wall mateials. Fo modelling ibs, othotopic mateial popeties ae used[4]. The stuctue has been analyzed fo the opeating condition. Since coolant channels ae milled in a helical patten the ibs ae idealized as an othotopic mateial with diffeent Young s modulus, Poisson s atio and shea modulus in the hoop, meidional and axial diections. Mechanical popeties at highe tempeatues fo the above mateials ae taken fom intenal design documents. The top nodes of the chambe ae suppoted in the axial diection. Combined mateial and geometic nonlinea stess analysis is done using ANSYS (Vesion 15.0). Detemination of Othotopic Popeties of RIBS The othotopic popeties of the helical ibs ae detemined by the following fomulae : Modulus of elasticity in adial diection w (2) Modulus of elasticity in axial diection Modulus of elasticity in hoop diection E E a E h w w c w 2 (3) cos w w c w 2 sin (4) w w c Shea modulus E x (5) G xy 2 1 xy Whee, w is the width of ib, w c is the width of coolant channel, is the helix angle with espect to vetical axis and is the Poisson's atio Loads Acting on Thust Chambe Duing combustion, the chambe will be loaded by intenal pessue and themal loads which will diectly act on the inne wall. The double walled constuction pemits the fuel to be passed though the space between the inne and oute walls fo enhanced cooling of the inne wall [4]. Due to sevee themal and pessue loads, it is obseved that the inne wall opeates in elastoplastic condition. Pessue loads The pessue inside the chambe is known as gas pessue while that in the coolant passages is called coolant pessue. Both these loads vay along the length of the chambe. Themal Loads Vaying themal loads ae applied to each and evey sections of chambe as pe the actual condition at which the chambe opeates. Themo Stuctual Analysis Both themal loads and pessue loads applied togethe and themo stuctual analysis done fo the peak loads. Fig. 11 shows the defomed shape of the thust chambe fo this condition. All ights eseved by 344

5 Fig. 11: Defomed shape of the thust chambe at peak load V. CONCLUSIONS The 12X18H10T stainless steel exhibited medium stength (yield = 290 N/sq.mm, ultimate = 624 N/sq.mm). Mode of failue of all specimens is found to be ductile. 12X21H5T stainless steel exhibited high stength (yield = 1148 N/sq.mm, ultimate = 1305 N/sq.mm) and low ductility. Similaly, 06X15H5MB also exhibited high stength (yield = 1091 N/sq.mm, ultimate = 1267 N/sq.mm) and low ductility. The coppe alloy exhibited low stength (yield = 86 N/sq.mm, ultimate = 217 N/sq.mm) but high ductility. Consistent test esults ae obtained fo the specimens tested in each lot. All the manifolds ae found to be in the elastic condition, maximum equivalent stess being 339 N/sq.mm which has a magin of safety of 0.98 against yielding. Maximum plastic stain of 2% is found to occu at the 12X18H10T to coppe alloy weld egion nea to the thoat. ACKNOWLEDGMENT The fist autho gatefully acknowledges the Diecto, LPSC/ ISRO and D. R. Muthukuma, Deputy Diecto, MDA/ LPSC fo pemitting to use the ceep test facility and computational esouces fo this wok. REFERENCES [1] Asaff A. K., Sunil S., Muthukuma R., and Ramanathan T. J., New Concepts in Stuctual Analysis and Design of Double Walled LPRE Thust Chambes, Poceedings of 42nd AIAA/ASME/SAE/ASEE Joint Populsion Confeence, 2006, pp [2] A.K.Asaff, S.Sheela, Kishnajith Jayamani, S.Saath Chandan Nai and R.Muthukuma, "Mateial chaacteisation and constitutive modelling of a coppe alloy and stainless steel at cyogenic and elevated tempeatues", Mateials Science Foum, [3] A. K. Asaff, Anju Paul, Ansu Mathew, S. Sheela, S. Savithi, Cyclic Stess Analysis Of A Rocket Engine Thust Chambe Using Chaboche, Voce And Ceep Constitutive models, Confeence poceedings, 7th Intenational Confeence on Ceep, Fatigue and Ceep-Fatigue Inteaction, IGCAR, Kalpakkam, [4] Aneena Babu, Asaff A. K., and Philip N., Fatigue Life Pediction of a Rocket Combustion Chambe, IOSR Jounal of Mechanical and Civil Engineeing, Vol. 11, No. 5, 2014, pp [5] David Roylance, Stess-stain Cuves, Depatment of Mateials Science and Engineeing, Massachusetts Institute of Technology, Cambidge, [6] Anonymous, ANSYS-Engineeing Analysis System, Release 11.0, Theoitical pocedues and element efeence manuals, [7] ASTM-E8, Tensile testing of metals, Ameican Society fo Testing and Mateials, Philadelphia, USA, 2008, pp All ights eseved by 345