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m)4x LLJwiCL~LI J DH Cw Z00004xUH.a)00cLo~00 rm0..N A0puL-JCc)I-1ia_*1J84U)UU)H0E-14HE-104C854.2.19SPONSONS, SKIRTS, AND OUTRIGGERSA separate finite element model was built exclusively tostudy the stress behaviour of the sponsons and skirts and tostudy the interaction between them and the outriggers. Sponsonand skirt model consist of 720 plate elements (eight noded quadand 6 noded triangle), were used to model the outriggers, and142 beam elements were used. Total number of the FEM activenodes for the whole model is 1136.
Each node has six Degrees offreedom-three rotations and three translations. Thickness ofthe sponson plates are 0.50 in., whereas the skirts and thevarious bulkhead are 0.31 in. thick. The various outriggersconsist of 1.5 in. Dia tube. The sponsons are constrained atthe nodes coinciding with the location of the main side plates.The load on the sponsons bottom plate consist of the weightof six batteries and the weight of the NBC unit and the variouscontrol boxes.
This load is 800 lbs. and distributed over anarea of 25 x 60 sq in. which represent a uniform pressure of 0.2lb/in. To study the effect of acceleration effects, a massdensity of 0.000732 slug/in, was used.The finite element model was analyzed using IFEM availableat the intergraph work station, because IRM is no longerTo account for the variousavailable ou the vax computer.forces acting on the sponsons and skirts, a combined case ofacceleration load of 12 G2 6 G, and 3 G in the longitudinal,vertical and lateral direction respectively was used.86Fig. (70) shows the finite element model includingsponsons covers.
The stress for the 1 G lateral case is13,500 PSI, as shown in Fig. (71). The lateral displacementis 0.3 in., as shown in Fig. (72). The stress due to thecompound acceleration is 122,500 PSI Fig. (73). Lateral andvertical deformations are in the range 3 to 4 in. as shown inFig. (74 and 75).The deformed shape is shown in Fig.
(76).It is obvious that stresses and deformations are excessive andthe skirts had to be reinforced, this was accomplished byadding a 1.5 in. tube (3/16 in. thick) at the location of thefirst outrigger. Fig. (77 and 78) show the FEM model withoutthe sponson cover plates. This model was analyzed under thesame loading conditions; stresses and deformations werereduced substantially.
For the 1 G lateral the stress isreduced to 13,400 PSI and the deflection to 0.4 in. as shownin Fig. (79 and 80).In the case of the combined acceleration,the stress is reduced to 41,000 PSI Fig. (81), and thedeformations to 0.5 - 1.2 in. as shown in Fig. (82 and 3);the defcrmed shape is shown in Fig. (6)By comparison,adding the strut, the stresses and deformations were reducedby more than 70%.Forces in the outriggers are maximum in the attachmentbolt at rear skirt element no. 13 in Fig.
(85) from whichmaximum stresses can be easily obtained as follows:87fFx+MzA-+S9zMyS9yWherefMaximum StressFxAxial Force (ibs)ASy, SzIy, IzMy, MzCross Section AreaSection Modulus About y and z axisMoment of Inertia About y and z axisBending Moments About y and z axis(PSI)Applying above equation yieldsf=72+0.7890+92,6305770.050.5+57,690+<3485.050.534,850Fy100,000 P5I88D14E-10N,CL,891-+F-.-4--- -- 1--4-1---.. 4MAI,-ALn004FE-F-NF-6-A1)'i9061')L'Jt6rj5'DIr-) t') c NJcJLJIIfC~*EIIIII*LsI.-L-"rnn4oo1 1H-914-C~-:-t---4G1-=M44-4-44-!01<-'ZL~tLiC%.Jr-lClI- C0Ile) qU-=rn)CD))0y-~V/)LLcyiVIn0092t.:-q£%F...oLX -rLCJU"' Ubn~'0A04z'r'4L/93-D3-CII.riZANKLLi""NO94!ZICl0UD4zU_C'Ar/95Z0il0U---0/\IH..,,%.Cr)%Ii0/\ ,4,U,:950ci.'zEoU)OLIxtp.960~_0WU1FWed~ ~Fr~0_0~.AF..FF~FF.FF.Fl*F~~.9F+ lyri-H----------i--tE-4-E-0....024..0H0rnW~98~72t72V1a-CN.ag-,E41;It IL994r-VAH-I--I----I--1- 4--c_3z r--- 2rFn c=~-t _2j1--FCr-+L~-.,DEA4H0~~E.-4'U)(ll UU )HcoaZ0Hpq<1.goz1aquR) U.~~LfrrIM.,no3ION-~wII54,RJ 4rNdny4loC) co~ C30(ar-ZC inU.C>C C))C0Co~rI-- In~ 13 ti)cM---Le'J oni N"rz~r a, U) t&)( c o (NJ Cf.)~I'- (,- (,ej z~'LLc4:*,~r-.-r 'I~Ir--IIICCC.IIlMAU)~ 0(C;.-JH UHZH10vH0F->Fjr~101A7-Iz csW.C400I-~~~/z4010(500(0II~~103Co CSX, I4 ..w4.l0wC)..~.4 .f.
.SNI.'..ww~-- i tnI- InIc0C5.w,.4w*4w4 wW~M,m'r-,(.--to(,--.4.0 ..u)m,-4.-to.-qa)-,t"(D-4T(T,.pqor. 0 ..><k-4-u I-d00....-- A -----Y.--,--m0wm-S-0cK0.C0 50000(Y)Y(,rm4-,Lo5 cocCD m ozc~0r,\0c.-0.*0W0-- I -A50m(DC?ov-,o s o-:--*44 .4L-S--r-00vcA r-, -45 *.Y) 0-- j6DIy.:coSS 0D-Lo....SlDau-I(.4 .+40)a)(0(.6.L-- A 0 0 --5jco I-Sf,m-4mAc.-40+)(r-,..-4)--icf.--01-1cD..+aCD CD wme4 -4*t (']--0*m 0-) LoL)L'1C.r-0..4 .4 ....
.4-4o0-4-t4"*()-.01-r-,Lp0:oc.)L).4..o-()-toda)C.)a 5,)C: CD 4"D0-4CO (D---..55"t.W.00o0SDr,()s...IOD *4pQSy 0t0Da I.)(,-,iunaa:Mct U-104L0Z4.3Dynamic AnalysisThe desire to determine the CATTB geometric arid operatingcharacteristics, such as gun, breach displacement, velocity andacceleration, chassis roll and pitch angle and suspension effectson the CATTB chassis due to terrain and firing loads, allnecessitate conducting a dynamic analysis for the CATTB.
Thiswas accomplished by building a dynamic model and analyzing it,using the DADS program on the Cray supercomputer. This studysupplements a concurrent simulation, study prepared by anotherTACOM directorate, since it mainly deals with the effect of thevarious dynamic forces on the CATTB Chassis.4.3.1DADS ModelTo create a DADS model, the geometry of the CATTB chassishad to be established. Road arms, idler and sprocket positionsmust be established with regard to Chassis CG. This is shown inFigures (86 - 88). The mass properties are established fromCATTB solid models (section 3.2) and summarized in Table 5.
TheDADS model consists of 17 rigid bodies, guns, turret, hull and 14road wheels. These bodies are connected by 16 joints, trunnion,ring, and 14 roadwheel attachment points, as shown in Fig (89).The track and suspension and terrain characteristics are imposedon this model, as shown in Fig (90).Suspension stiffness anddamping curves utilized where those of Teledyne 3870 ESS Seriesas shown in Fig (91 & 92).105These two curves are transformed into torque versusangular displacement and torque versus angular velocity by usingthe following formulas:T = FR cos 0A = R sin 0WHERE:TRFA0:::::(lb - in)TorqueRoad Arm Length (17 inches)(lbs)Force(inches)Wheel TravelRoad Arm Angle From horizontal position.TheThe resulting curves are shown in Fig (93 & 94).inFig(95).isshowngunusedimpulse curve for the lightweight(96).Figinshownisprofile4whoseAPGThe terrain used wasA more drastic custom-made profile with a series of bumps andholes (spaced to maximize terrain effects on the Chassis), canThe CATTB DADS model was driven at abe used in Fig (97).constant speed (30 mph), and the acceleration and forces atvarious location were calculated.
It is worthwhile to mentionthat the hydroneumatic suspension model runs on DADS were notsuccessful. In lieu of waiting for the DADS code to be fixed,In thean MI suspension was used on the CATTB DADS model.future, when the DADS code is fixed, a follow-up study can beperformed with minimum efforts. A detailed input file for theDADS model is attached in Appendix D.4.3.2.DADS ResultsA DADS model was analyzed under two separate load cases sothat they could be combined at any time step and with anyproportion desired.
The first load case is ABG4 terrain effectson the CATTB. This can be presented in the form oftime-dependent curves for the following parameters:4.3.3Terrain EffectsPitch and Roll AnglesFig 98Vertical Acceleration of Chassis at C.GFig 99Vertical Acceleration of First RoadFig 99Vertical Forces in Road Wheels 1,4 and 7Fig 100Vertical Forces in Road Wheels 2,3,5 and 6Fig 101Maximum Vertical Chassis AccelerationFig 102Maximum Chassis Angular AccelerationFig 103106Maximum Vertical Forces in roadwheels (Case 1):LI, L4 and L7Fig 104L2, L3, L5 and L6Fig 105RI, R7 and R7Fig 106R2, R3, R5 and R6Fig 107Maximum Vertical Forces in roadwheels (Case 2):LI, L4 and L7Fig 108L2, L3, L5 and L6Fig 109RI, R4 and R7Fig 110R2, R3, R5 and R6Fig 111Case (i) assumed maximum bending to cocur under firstroadwheel and it occurred at 23.8 seconds.
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