TSU F.E ANALYSISTSU F.E ANALYSIS

YAIR SOFFAIR

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Dynamic Response Calculation Temperature Distribution LOS Retention due to TemperaturesDesign Recommendations

Model DescriptionModel Description

TSU Casting and CoverOptical BenchHoodPCB’sMirror, Flexures, Optical Elements, MassesBolts and Thermal Resistances

The Optical Module and The Optical Module and Mirror AssemblyMirror Assembly

Loads and RunsLoads and Runs

Operating (68W) in 52 C Ambient Natural Frequencies15 g/11msec Shock on 3 Directions24 g Static EnvelopeRandom Vibrations on 3 Directions

Structural Analysis - Boundary Structural Analysis - Boundary ConditionsConditions

Thermal Analysis Boundary Thermal Analysis Boundary ConditionsConditions

The Ambient Temperature outside was set to 52 C

Convection Coefficients were calculculated and entered

The Temperatures inside were calculated during the Analysis

MMaterialsaterials

Casting - Al 356 Mil-A-21180 Class 11Flexure -Al 7075 T 7351Flexure - 17-4 PH H 1025 SteelMirror - RG 715Adhesive - Ablebond 724 - 14CLenses - SFL 6PCB’s - Polymide+Copper layers

ResultsResultsNatural Frequencies118 Hz - Supply card Bending126 Hz - Optical Module Bending136 Hz - Video card Bending155 Hz - CPU card Bending166 Hz - Supply card Bending189 Hz - Video card Bending202 Hz - TSU Twisting+legs&CPU Bending204 Hz - CPU Bending227 Hz - Optical Module & Flexures Bending

Second Natural Frequency - 126 HzSecond Natural Frequency - 126 Hz

Seventh Natural Frequency - 202 HzSeventh Natural Frequency - 202 Hz

The Maximum Accelerations during The Maximum Accelerations during 15g/11msec Shock in X direction15g/11msec Shock in X direction

Element Acceleration(g)R 17Lenses 1-4 15.3CRT C.G 16.4CRT Optical center 15.3Mirror 15.9Antenna 15.3

The Maximum Accelerations during The Maximum Accelerations during 15g/11msec Shock in Y direction15g/11msec Shock in Y direction

Element Acceleration(g)

R 15.1Lenses 1-4 15CRT C.G 14.9CRT Optical center 15.1Mirror 17.3Antenna 15.2

The Maximum Accelerations during The Maximum Accelerations during 15g/11msec Shock in Z direction15g/11msec Shock in Z direction

Element Acceleration(g)

R 14.9Lenses 1-4 15.6CRT C.G 15.1CRT Optical center 15.3Mirror 23Antenna 15.1

The Accelerations on several The Accelerations on several components during Z Shockcomponents during Z Shock

Maximum Accelerations and Maximum Accelerations and Displacements on PCB’s - Z ShockDisplacements on PCB’s - Z Shock

PCB Acceleration(g)

Displacement(mm)

CPU 22.6 0.3

SUPPLY 26.6 0.59

VIDEO 24.5 0.41

Checking the PCB’s - Steinberg Checking the PCB’s - Steinberg Criteria during Z ShockCriteria during Z Shock

The critical PCB is the Supply PCBThe Displacement on the critical

component is 0.53 mmThe allowed Displacement for such

component according to Steinberg criteria is 1.41 mm

The displacements on Supply while The displacements on Supply while subjected to 24g static load - Zsubjected to 24g static load - Z

The Maximum Stresses during The Maximum Stresses during 24g static envelope - X direction24g static envelope - X direction

Component Stress(Kg/mm^2)

M.S

TSU casting 1.8 10.5Optical Module 1.8 10.5Al Flexure 4.5 8.1Steel Flexure 8.5 10.8Adhesive 1.07 1.36Mirror 0.98 1

The Maximum Stresses during The Maximum Stresses during 24g static envelope - Y direction24g static envelope - Y direction

Component Stress(Kg/mm^2)

M.S

TSU casting 4.7 4.0Optical Module 2.8 6.8Al Flexure 6.3 5.8Steel Flexure 9.7 9.4Adhesive 1.35 1.08Mirror 1.23 0.81

Principal Stresses on the Mirror, 24g Principal Stresses on the Mirror, 24g static envelope, Y directionstatic envelope, Y direction

The Maximum Stresses during The Maximum Stresses during 24g static envelope - Z direction24g static envelope - Z direction

Component Stress(Kg/mm^2)

M.S

TSU casting 3.7 5.1Optical Module 4.4 4.3Al Flexure 16.4 2.2Steel Flexure 12.8 7.1Adhesive 2.65 0.19Mirror 2.42 0.41

Von Mises Stresses on the Optical Von Mises Stresses on the Optical Module, 24g static, Z directionModule, 24g static, Z direction

Von Mises Stresses on the Al Von Mises Stresses on the Al Flexure, 24g static envelope, Z Flexure, 24g static envelope, Z directiondirection

Design ImprovementsDesign Improvements

Adhesive thickness is increased to 0.35 mm.Three flexures and two ribs were added to

the Optical Module in order to increase the second natural frequency and reducethe gains.

The Mirror thickness was reduced from 13 mm to 11 mm.

The new bonding configuration The new bonding configuration

The Maximum Stresses during The Maximum Stresses during 17g static envelope - Z direction17g static envelope - Z direction

Component Stress(Kg/mm^2)

M.S

TSU casting 2.7 7Optical Module 1.2 15.8Al Flexure 7.2 5.1Steel Flexure 4.3 21.2Adhesive 0.34 1.48Mirror 0.34 2.94

Tensile Stresses on the Adhesive, Tensile Stresses on the Adhesive, 17g static envelope, Z direction17g static envelope, Z direction

Random Endurance Vibration XRandom Endurance Vibration X

Random Endurance Vibration YRandom Endurance Vibration Y

Random Endurance Vibration ZRandom Endurance Vibration Z

The RMS Accelerations during The RMS Accelerations during Random Vibration, X directionRandom Vibration, X direction

Element Acceleration(g)

R 2.11Lenses 1-4 2.16CRT C.G 2.33CRT Optical center 2.02Mirror 2.5Antenna 2.06

The RMS Stresses during The RMS Stresses during Random Vibration - X directionRandom Vibration - X direction

Component Stress(Kg/mm^2)

M.S

TSU casting 0.09 HIGHOptical Module 0.29 HIGHAl Flexure 0.63 HIGHSteel Flexure 1.14 HIGHAdhesive 0.03 HIGHMirror 0.03 HIGH

The RMS Accelerations during The RMS Accelerations during Random Vibration, Y directionRandom Vibration, Y direction

Element Acceleration(g)

R 2.94Lenses 1-4 3.05CRT C.G 2.83CRT Optical center 2.92Mirror 4.02Antenna 3.18

The RMS Stresses during Random The RMS Stresses during Random Vibration - Y directionVibration - Y direction

Component Stress(Kg/mm^2)

M.S

TSU casting 0.5 HIGHOptical Module 0.6 HIGHAl Flexure 1.48 HIGHSteel Flexure 1.65 HIGHAdhesive 0.05 HIGHMirror 0.05 HIGH

The RMS Accelerations during The RMS Accelerations during Random Vibration, Z directionRandom Vibration, Z direction

Element Acceleration(g)

R 2.0Lenses 1-4 2.03CRT C.G 2.1CRT Optical center 2.04Mirror 2.0Antenna 1.99

RMS Accelerations & Displacements RMS Accelerations & Displacements on PCB’s (1on PCB’s (1), Z (C/Ccr=2%) ), Z (C/Ccr=2%)

PCB Acceleration(g)

Displacement(mm)

CPU 15.7 0.166

SUPPLY 9.7 0.179

VIDEO 10.3 0.142

The RMS Stresses during Random The RMS Stresses during Random Vibration - Z directionVibration - Z direction

Component Stress(Kg/mm^2)

M.S

TSU casting 0.33 HIGHOptical Module 1.5 HIGHAl Flexure 0.85 HIGHSteel Flexure 0.51 HIGHAdhesive 0.04 HIGHMirror 0.04 HIGH

Checking the PCB’s - Steinberg Checking the PCB’s - Steinberg Criteria during Z VibrationCriteria during Z Vibration

The critical PCB is the CPU

Total life time : 5.5 hoursM.S=2.74The PCB’s free edges must be

captured and bonding of the critical components to the board is recommended

Thermal Analysis - 52 C AmbientThermal Analysis - 52 C AmbientMain parts temperature distributionMain parts temperature distribution

Main Housing : 58.1-67.9 COptical Module : 62.6-69.3 CHood : 57-61.5 CCover : 55.1-67.2 CFlexures & Mirror :61.2 CCPU : 67.8-78.7 CSupply PCB : 67.2-83.2 CVideo PCB : 70.5-80.6 CVideo H.S : 71-79.2 C

The inside TemperaturesThe inside Temperatures

PCB area : 69.5 CR area : 60.6 CHood inside air : 61.2 C

L.O.S Retention - operation in -30 L.O.S Retention - operation in -30 C C (CRT contact angle 38(CRT contact angle 38) )

TSU R TOTAL

Elevation(mRad)

0.08 0.157 0.237

Azimuth(mRad)

0.526 -0.203 0.323

L.O.S Retention - operation in 52 L.O.S Retention - operation in 52 C C (CRT contact angle 38(CRT contact angle 38) )

TSU R TOTAL

Elevation(mRad)

0.048 -0.176 -0.128

Azimuth(mRad)

-0.207 0.111 -0.096

Temperature distribution on Temperature distribution on the optical Modulethe optical Module

Temperature distribution on Temperature distribution on the CPUthe CPU

Discussion and RecommendationsDiscussion and Recommendations

There is no stress problem.The critical dynamic case is Z shock.The critical parts are : Al Flexure,

the Adhesive and the Mirror.The critical PCB, Z shock : Supply.M.S=2.66The critical PCB, Z vibration : CPU.

Discussion and RecommendationsDiscussion and Recommendations

M.S=2.74 free edges should be captured and

bonding of the critical components to the board is recommended.

L.O.S Retention during operating in 52 C is very good in elevation even while adding the R error.

Discussion and RecommendationsDiscussion and Recommendations

In azimuth, the error is strongly dependent on the contact angle between the CRT and the Optical Module.

In order to minimize this error, the contact angle is set to 40°.

L.O.S error during operation in -30°C is larger, but within the allowed tolerance.

Discussion and RecommendationsDiscussion and Recommendations

significant improvement can be made by Temperature or electrical calibration.

The critical PCB’s : Video & Supply.Gap filler (T-form 460) is added to the Video

hot components in order to transfer heat to the H.S.

Gap filler is recommended to connect the PCB hot component to the Main Housing.

Discussion and RecommendationsDiscussion and Recommendations

Sinusoidal scanning of the Optical modulealone (3 flexures) showed first natural frequency of 150 Hz.

Thermal experiment of the system operating at 52°C showed temperatures of 71°C on the CRT interface and mid wall.Analysis showed 69°C, 68°C respectively.