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To have access to this software, it was necessaryto transfer the CATTB FEM model to the Cray Supercomputer. Toaccomplish this, the CATTB FEM model, which was built using IRMSoftware on the Intergraph CAD System, had to be transferred tothe prime computer and had to be translated into PATRAN and theninto NISA. Then it had be brought back to the Cray foranalysis.This tedious procedure proved to be useful, due tothe amazing speed at which the analysis could be performed onthe Cray supercomputer.4.4.1Dynamic Effects of Terrain ForcesIn the dynamic analysis of CATTB (section 4.3), the forcesin the roadwheel attachment points were found to be timedependent and were maximum at roadwheels 3 and 4, as shown inFig (117).In the static FEM analysis (section 4.2), theseforces were calculated as support reactions and were maximum atroadwheels 1 and 7 (Fig.
124).To reconciliate between the tworesults, the roadwheel attachment points had to be allowed tohave relative movement to each other so that the correctedsupport reactions in the Static FEM analysis would equal thosefound in the dynamic analysis.153The relative movement for all roadwheels attachment pointscreated additional stress in the chassis which had to be addedto static FEM analysis stresses (Fig 125 shows the chassisstresses due to vertical movement of 0.10 inches at first leftroadwheel).To maximize the effects of Terrain Dynamic Forces,the forces in the roadarms attachment points obtained from DADSanalysis were chosen in such a way that they caused maximumbending in the chassis. Two cases for these terrain forces wereconsidered; the ftrst case yielded maximum bending at firstroadwheel, whereas the second assumed maximum bending at thefourth roadwheel.
The dynamic effects of the terrain forcescould easily be visualized by comparing the results of thestatic FEM analysis (Fig 123) and the results of Dynamic FEManalysis (Fig 126 & 127)Total VON Mise stresses for the two terrain cases areshown in Fig (128 & 129) and Fig (130 & 131)4.4.2respectively.Dynamic Effects of Firing Load:In the previous FEM analysis (section 3.2) the firing loadwas considered static. To account for its dynamic nature, adynamic load factor of 2 was used as a multiplier. To study thedynamic nature of the gun firing load, a transient dynamicanalysis was required.
The first step in this type of analysiswas the modal analysis or EIGEN VAWE and EIGEN VECTOR analysis(natural frequency and vibrated shape).This was accomplished, and the results were satisfactory(Table 6 - 8).However, the binary files, which will be used inthe transient dynamic analysis, could not be properly translatedfrom analysis results. Further studies in this area can beresumed when future software revision enables correcttranslation of the binary files.154'TvM M'vuV-NrmwG)CuC'Mm)vOLAVuNriV-t-V-V-Ir1qNt')NVA-LILUU)00HHUE)W0I-.O1I-Uot(3:'E-1U)EJ*IUO1550cizG:E-+HS)U)++0:(0)+U~0)+oo+-+Lor'-[a~r'apa(0003H:oQ001156QIJJO91n +0limr- o r7 m Ilctr.co-1La)t a)) m44'(ACoU)...4.,14E1-41=rj'rHd00U)LIHU")1Nwwp0. .
. ...I-G:015LUIL--Vv++++++V" 0r~-V00CXu 00C00+ISCULA1-U)V-C600+++++MmM 00M(.0 V CU Cr)CUr(1-(IIIII++++U)Wr-CrW-IlI(Y1LA1:U)00LAIW0c0H-0ILHU))ILUcll-cr158o~(r)wwSNLD-(DCDL)cuV*Lbw(Um1TNUw0"CC4f-0Ao00N40N0-Dw14-4000U-.C01L59V)mJr0~~fU))D(r4coChniIL(7)00i-(S0000U)04 H.c JOmCLIE-41I46uiILnE-u160eIIIIllLUIW0If)c,LiiI 13cMnCZ>coLb4*ammINX>-wwIwzcoIN1--LOLLOiU..-+1-w-U-U.1161-O4~~~~.dto)dJMLI>CL~49HP54-~.~EH1=LCUC)o ccl'-wLab(D~N~ Wuf~i-r~m~Lb~r.-vu0iI-cu'CNaIMICo0wOLIIx4000coxtowwLO4=163E-4-w0HmK41)I-(McioNwwmwwmmrmCom~mi w-mmSwwwwwcm0mwm00mmmEk4+.4w+++++1++1+wwwwwwwwi+wiw+W+wi+wi+W+W+W+Lvi4LL.+wLLmwm+wmm+Wmm++w+ww+wwww+++Ew165*D*O++N)CDCD0000oC')cV*rI*CfoPINConLUl~NH0CoLO000N'-4'-40+E-4L00C0000NCO0nN000DE-1ccz0DLUCocc>>o*0p-4+++0*oI0IInw0DLULULUOmU+CococInN0+LULU04rco00in cc00o0coNV-1NN NCo'o-'03 HLUIs.0>-+ZocowS mAWZwnLUT-Nw1-40*-+LUU))*0N+LUNw-N4mCE-8m)0-a)4CD0LU+LUw0M-*w1665.Conclusions:5.1 Turret Design - The new locations of the turret side-platessignificantly increased turret strength and kept stress at itscurrent level.
Whereas locating these side-plates in similarfashion to the MI Turret could have resulted in higher stressesand deformations, due to the reduced turret strength.5.2 Trunnion Design - It is recommended that the size of thebolts in the gun-mounting block not exceed 3/8" to minimize theloss of the resisting area, and the pretension load in thesebolts should not exceed 6000 - 8000 lb/bolts, because it willcreate additional stress in the trunnion in the range of (9,000- 12,000) PSI.5.3 Casting - Hull casting reinforcement is needed.
It can beachieved by extending the casting plate to the chassisside-plates and should not be compromised.5.4 Power Pack Mounting - From stress analysis results, it isclear that the power pack will not cause excessive stress in thehull floor plate. But the current analysis did not consider therigidity of the power-pack, which is more than enough totransfer its weight to hull side-plates. In this case, thefloor mounting will not only be ineffective but it might be anuisance, since the floor plates are not stiff, and it mighttransmit unnecessary vibration to the power-pack components.For this reason, it is better to utilize side-plate mounting forall major CATTB components, such as the auto-loader and thepower-pack.
This will allow effective optimization for floorplates.5.5 Design Optimization - It is recommended to optimize thedesign (when optimization software becomes available) to reducethe percentage of CATTB basic structure weight (currently it isabout 30%).1676.2 Recommendations:This study was conducted under extraordinarily difficultcircumstances due to the relatively recent software utilized(EMS, IGDS, IRM, IFEM, PATRAN, NISA), which is under continuousrevision, not to mention the operating difficulties encounteredon the VAX computer.
All this combined complicated and hinderedthe interface between various design stages, and it did notallow this study to be concluded to the extent intended.Therefore, the following recommendations are directed towardimproving the operating system.6.1 It is beneficial to obtain a translator from intergraph FEMsoftware (IFEM) to analysis software ABAQUS. This translatormust provide complete translation for FEM Model (Load, Materialand Element Properties etc.) and it must be available in theCray supercomputer.6.2 It will be beneficial to obtain a translator from futureanalysis software ABAQUS to DADS software.
This will makebuilding a DADS model for dynamic analysis much easier, and itwill allow an iteration process between Dynamic Analysis andFinite Element Analysis, which is essential for designoptimization.6.3 It will be beneficial to obtain optimization software towork closely with analysis software ABAQUS.6.4 The implementation of the various software and hardwarerevisions should be made coincidently and not more than once ayear to allow smoother transition between design stages of longproject.6.5 DADS program (Tracked Super Element) should be enhanced sothat it can handle hydroneumatic suspensions and DADS softwaremust be debugged thoroughly.16844cO+CC)U,C-I- C I C.)40xN-Ir4-'_..Lcot:)•~S0o~ 0 ~~Cc",-'1,(U4-41-COL0::(4-J(0I-I*0I:+----:40 -.NN rcO1CJ- -cp.- COSI--H0a-20g '.-Q-=D(00.O=+ILLr= W Qw W -W $ 4-I>-.+-e1 ::'rww.i::I)4+-aN* C)cI -40C" W fC CD N* .,W'-4CMCOL.
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