Design Analysis ‘n Manufacturing

By- Yogesh Arora and Sangam

Sinha

CZT – Imager Payload Structural Configuration

Initial structural configuration of the payload was set keeping following fundamentals

1. Past experience 2. Weight constraint 3. Science requirements

Analysis Objectives Based on Static and Dynamic load

conditions provided by ISRO following objectives were drawn

1. Natural frequency of CZT Imager assembly 2. To check stresses and deformations on all

parts of the assembly, particularly fasteners surroundings under static and dynamic load conditions

3. To optimize Fixed and Structural mass

Assumptions and Boundary Conditions

All Fixed masses are rigid bodies Collimator plates are rigidly integrated The payload is considered fixed in

translation and rotation at the bolted locations on the deck

The assembly has been considered as integration of finite discrete masses, hence posing a case of Multi-Degree-Freedom-System in fundamental co-ordinate system

Analysis technology and meshing details

Finite Element method is applied for Eigen Analysis using IDEAS, FEMAP and NASTRAN software

Total number of elements – 77922 Total number of beam elements – 1209 Total number of shell elements – 76649 Total number of lumped mass elements –

64 Total number of nodes - 77013 Total degree of freedom -

Weight breakup of CZT Imager

Component Weight (Kg)Cross 0.238Collimator 23.86Calibration housing 2.181PCB with CZT modules 10 CSI box 16.2CSI housing 2.051Electrical housing 2.745HV box 1.877ALPHA box 1.117Fasteners 0.171Total weight 60.44

load cases

Load Case

Description

1 Self Weight

2 20 G out-of-plane (+ve Z direction)

3 15 G in-plane (+ve Y direction)

4 20 G out-of-plane (+ve Z direction) + 15 G in-plane (+ve Y direction)

Results

Iteration 01  

Eigen Analysis

Iteration No. Description Fundamental Natural Frequency

1 0.7mm structural wall thickness and 1mm for flanges and minimum bolting locations

26 Hz

2 0.7mm structural wall thickness and 1mm for flanges and increased bolting locations (24 places)

38.5 Hz

3 Increased structural thickness (1mm on walls and 2mm for flanges) and minimum bolting locations

53.5 Hz

4 Increased structural thickness (1mm on walls and 2mm for flanges) and increased bolting locations (24 places).

75 Hz

Mass participation details of iteration 04, up to mode 3

  X direction (mode 1)

Y direction (mode 2)

Z direction (mode 3)

Total Mass

0.426028 0.428430 0.640961

Mass participated

0.320695 0.322651 0.299465

Percentage 75.27 75.31 46.72

Iteration 04 – Principle Mode Shape

Static analysis results

Load case Maximum displacement (mm)

Von – mises stress (N/mm ²) Remarks

1 1.85E-02 Plate elements near bolts – 4Stiffeners/flanges – 2.22Bolts – 4.44

 

2 0.371 Plate elements near bolts – 89Stiffeners/flanges – 35.5Bolts – 68.5 

Corner bolts in CSI, Dummy hsg and adjoining plate elements experiences max stress and deflection

3 1.03 Plate elements near bolts – 75.5Stiffeners/flanges – 20Bolts – 115 

Bolts on the cross, Corner bolts in CSI, Dummy hsg and adjoining plate elements experiences max stress and deflection

4 1.03 Plate elements near bolts – 117Stiffeners/flanges – 45Bolts – 178 

Bolts on the cross, Corner bolts in CSI, Dummy hsg and adjoining plate elements experiences max stress and deflection

The Next Step

On the current baseline new team with members from ISAC and TIFR has been formed to reconfigure the whole system

New team has tasks e.g. to minimize weight, analyze every part in detail, rearrange mounting arrangement etc.

Manufacturing

Besides several highly accurate conventional machines our workshop houses 3 CNC Milling machines, 1 CNC lathe, 1 NC EDM and 2 high precision DECKEL universal milling machines

The workshop also possesses advanced pulse controlled TIG, Plasma welding and cutting machines

Thus our workshop enjoys the status of both, a well-equipped precision Tool Room and a reliable fabrication shop.