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To accomplish this, it is necessary to torquethe load mounting bolt so that the total pretension in them canresist the rebound recoil force. This pretension force is acompressive force applied at the perimeter of each mounting-bolthole. A pretension load of 3200 lbs per bolt was used. Thiswill give a 50,000-lb resistance or about 14% of the recoilforce.4.2.7Trunnion Analysis ResultsThe maximum VON mises stress is 57,000 PSI, and it occursjust below the surface of the inner face of the trunnion at theedge of the slot for mounting the gun block (Fig 30).Adetailed stress plot for this area is shown in (rig 31).Themaximum stress due to pretension load of 3200 lb/bolt is in therange of 4000-5000 PSI, as shown in (Fig 32).Maximumhorizontal deformation is 0.022 inches, as shown in (Fig 33).To keep stresses and deformations at their current level.
Thedistance between slot and trunnion edges had to be increasedfrom 3.0 to 3.75 inches, and trunnion thickness was increasedfrom 4.5 to 5.5 inches as a result of this analysis.40~~~*~iillT.-a~aalle.i.'paalliititrr.la'1'~~~~~~~~.... a~~~ta~~atu...r0..lrRua.Pr.2"lPalAIOSO.Iwa to < al7-7~fn OiitWIR-la;ll-- a-ItA2*..-TR[UNNIONFF'M MODET,42~IvjC.i'7H... .............. ............ ...........
... .......C..... .THH...... ... .3UNIX IHIH'-!1:4:FIlijl'HHhV00LH--0-70butIi'VMm4.2.8Turret and Hull CastingsThe turret and hull casting, are complicated parts and theirinteraction through the race ring deserves a separate study byitself. To represent turret and hull casting in this study inthe best possible way some simplifications were necessary. Theturret race ring was replaced in the FEM Model with a stifftruncated cone (2.5 inches thick).This allowed the forces tobe transferred from the turret to the hull with minimumdeformations. The hull casting configurations in the finiteelement model were obtained in such a way that the hull castingFEM model has the same mass properties obtained for the 3D solidmodel available on the Intergraph CAD System and obtainedutilizing EMS.4.2.9Casting Analysis ResultsStresses and deformation for the turret and hull castingswere extracted from the total chassis results for the followingtwo cases:4.2.9.1Gun Firing At 0 degrees HorizontalMaximum VON mises stress in the turret and hull casting isin the range of 30,000 PSI as shown in Fig (34 - 36).Stressesin these casting around the trunnion area are shown in Fig (37 &38).Vertical deformation plots are shown in Fig (39).4.2.9.2Gun Firing at 90 degrees HorizontalMax VON mises stress is 36,000 P31I as shown in Fig (40 &41).Lateral displacement are shown in Fig (42).Stresses intrunnion and hull casting and around road where no 3 are shownin Fig (43).47L)a)V)0Ou wa)a'Mcoso AT)LdWco.iU)ina!inzLw-wrutU)LO"fllItm.M~0N(sNi-toNNru\~a1(x mx>inww-03~3~KD0.CC1-4C.r_a-JJC-:FIG 34STRESS IN TYRRET AND HULL CASTINGS-GUN48FIRING AT U4En V)OU-uwIflWDW44H(~UczLEDOZh~:0oro(n.'J0-,I~laUSTRESI TURETANDHUL'LACASTINGS-GUN49!eIRING AT 0f)NIHIA NAfl-SDNI.LSVo) 'Pifl'IV9FQNVlaailn ISSadTsDidLrm'nMH0I-u-omr(n(n0*0a03CC;aC(A(.()Lnm;uM03) F~rd-4rkaN03nxf-iLnCDUl1n4co0WaMm0c,03(Am+a)co ((ajGVfl) 4s (VaU)-LlU)(Uco(D)Lb(Dco4U-in-Tco vL ocu0runj'TcWTC)0n \X)0: 0.j a~,0 CccC0HLcioIdJ&"rFIG0-S').RESSAD CURETHLL CSTINS-GNFIINGAT0 IV Dmi'daRnD-SDN4ISVO 'vinii GNV Itiali XTssR.*.s000Hrn-D0co00CCL-(0atn&nN-(3)\oI'XDC~ H-.3 -JCi)fli-CCOD-*(Aw 3 G3)DWlWuFff,AU(0_0wAm+0(n(11.40~ 4Wi-.oOr(1r(nl0303n*3a)O'w.(0(ofllA)4.cflfc)ZOTJV ONINIIANflD)-SONIISVO'1'fl14 UNV00vn E: 0 m* t'w UuJLgI)Ifll NI SNOIIVWN1OAH(runUUl(U0IwL)u-0m.Cw0)w'm1,1ur0'IVVI.104(X>NXNLU0uCLPI*I'1Nn0iZU)Ir00U)0LLJLCDD0oLLULVf7006IV O)NI-8I.A NflO)-SD)NlISVlOf? DiA1'flB tINV .L3M.T.
NTcm0m2rri3Z-2~(C4Z5 U CO& (D Ed0Ill-XiIn!1.fu110M-ru10(ro0(I-fT)MvrdCDCDDcil (fSS3HIIS06 IV D94I21IAN~ Ax JAhAflD-VSfDMI.SVDTVDad-J- 0) C CJaUV))(Y),4U)toUNY(VCN U )CU4(U(oMI19,M1nMRlfl-(pI)VUW"T1oSaNLLSrwjctr'D0(n)00a-yCc:tL=0 ccaC~LU0m:06 IV DNIEIA NflD-SO)NIISVO)aco-u-Ilqfll4 GNV IH'd~fllLDRDU)itcu(UI)aa(nI~CCD0LI)C)LiL00.0.LI-iiIL:cc w-0.Z) I-a:L)toaootAUAJwI~La.La0cc(Z~mI0w w(D(m HDicc~'IJH11-4w_w__oll,__00LnLCLSTES0URTADHLCSIG-FIG 43GNFRN57~T91Hull Model4.2.10The MIAI hull will be used and modified where necessary toassure strength and space utilization. The hull finite elementmodel was created using IRM software in similar fashion to turretFEM model.
A wire frame was created from a 3D solid modelavailable on the Intergraph CAD System. Then this wire frame wastranslated to IGDS and transferred to the VAX computer to serve asa skeleton for the finite element model Fig (44).Thickness of thevarious plates are shown in Fig (45).The hull was constrained inthe vertical direction at all roadwheel attachment points. In thehorizontal direction, the hull was constrained at the attachmentpoints of the roadwheels 1 and 7, to maximize the bending effectsin the chassis due to lateral loads.Hull Loads4.2.11The reaction forces in the 48 mounting bolts found in the FEMturret analysis (Appendix C) was applied on the hull model andanalyzed.
The results indicated high stress (130,000 PSI) in thehull top plate around the trunnion area. In this preliminaryanalysis, the interaction between the turret and hull was notconsidered, resulting in high stress. To represent the realsituation, this interaction must be considered. For this, it wasnecessary to merge turret FEM model with hull FEM model resulting,in chassis FEM model Fig (46 & 47).This model will be analyzed asone entity.4.2.12Hull Analysis ResultsGun-firing load was applied to the chassis FEM model, and theresults are as follow:4.2.13.1Gun Firing at 0 degrees HorizontalStresses in the hull are in the range of 60,00U PSI, as shownin Fig (48).4.2.12.2Gun Firing at 90 degrees HorizontalTo investigate this case, another CATTB FEM model had to becreated by rotating the turret 90 degrees as shown in Fig (49).This model was analyzed, and the hull stresses are in the range of(95,000 - 130,000) PSI Fig (50 & 51).Depending on the number ofroadwheel attachment points constrained in the lateral direction (7and 2 respectively), the hull lateral deformation for these tworanges from 0.16 - 0.25 inches, as shown in Fig (52).The hull'sdeformed shape are shown is Fig (53).tton ote that shear stress if, the hull (36,000PSI) is closer to its yield limit (50,000 PSI) than bending stress(65,000 PSI) to its yield limit (100,000 PSI).This is due to thedominant shear behavior in the trunnion, turret, and hull castingnear the trunnion area.
Chassis deformed shapes are shown in Fig(68 & 69).i584.2.13Hull Modification (1)Hull stresses and deformations were excessive, and the hullhad to be strengthened. This was accomplished by eliminating theblow-off panel in floor plate and by reducing the size of theopening in the middle bulkhead as shown in Fig (54).4.2.14Hull Analysis ResultsAfter these modifications, the chassis was analyzed again.The stresses were reduced to (70,000 - 90,000) PSI Fig (55 & 56),and the lateral deflection were reduced to 0.15 - 0.2 inches Fig(57 & 58) for the two cases of roadwheel attachment pointsconstraints mentioned previously.4.2.15Hull Modification (2)Stresses and deformations are still reasonably high. Thehull had to strengthened in the lateral direction.
This wasaccomplished by extending the hull casting plate between the twoside-plates as shown in Fig (54).4.2.16Hull Analysis ResultsStresses were reduced to the 45,000 PSI range andThese values aredeformation to 0.10 inches Fig (59 & 60).over-estimated due to the simplicity of contraints assumption.In reality, all seven roadwheels resisted lateral displacement toa varied degree. To understand this behavior, a dynamic analysisis required when the turret is rotated 90 degrees.4.2.17Hull Modifications (3)It was found necessary to reduce the height of the rearThebulkhead, in order to be able to install the Auto Loader.rear bulkhead contribute to hull's lateral strength.
To studythe effects of the bulkhead height on the chassis strength andstiffness, the bulkhead height was varied (from 33 to 20 & 13inches).4.2.18Hull Analysis ResultsStresses in the hull were observed and are shown tn Fig (61 Deformations are shown in Fig (64 - 67). The results63, & 67).indicated that the rear bulkhead height could be reduced to halfof its original height before any significant reductionin 1 ,,llo4-....^-nd st lffness could Le observed.59FIG 41,LIU",[- FEM MO1DE'60a;iA4c.4.X2-jjc'J1ccm0(JL.-AtdrL4EMER-OE614ri-------' i........as.: ...,--------..~ii...........4=-44C4.4....
4 ........4r432.......... 4~-4j:.-;F1.14.~4 -.;~1134yf', 1U,-a.~.. .........------------.4=.~~~'~.4~a-.--44.4.---------;.4~~~~~ ~ ~ ~ ~ 24444...;~ ~ ~ ~ ~ ~ ... ...~~ ~ ~~%4.4".4..4..,..444'4..4N . .. ........4.' f- 4 -:".........11:iK4.4....-44..''j..... '..-444.-------4'.C.1...----- - ------~ ~~ ~ ~-4.4''...~ ~ ~I"'2"4."IEl*~..4 .~...46''FIG,,T 4H4.........46B..4'I2FEMODE.. ....4YIG 47CATTR CHASSIS iVZM MODE..63.1E-4U)E-E'-Q~zU)NH....Ei+!,LU.--LO..... ................ .
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