Shock & Vibration:

Case Study

For Northrop Grumman Information Systems

LX Course: 3rd Quarter 2011

The presentation material is a proprietary property of Luxea & Dunamis Inc.

Contact the company for appropriate distribution.

Luxea Inc. / Dunamis Tech Inc.

2 The presentation material is a proprietary property of Luxea & Dunamis Inc. Contact the company for appropriate distribution.

Chassis/PCB – Random Vibration

Luxea Inc. / Dunamis Tech Inc.

3 The presentation material is a proprietary property of Luxea & Dunamis Inc. Contact the company for appropriate distribution.

Live meeting number:

1-877-740-2201

Pass code: 9702761

SCHEDULE

Week Topic/Case Study Date

1 Overview and Introduction 10/3/2011

2 Review of Shock & Vibration for Electroincs I 10/10/2011

3 Case I: Transportation random vibration 10/17/2011

4 Case II: Rack on isolators – pulse shock 10/24/2011

5 Case II: Rack on isolators – pulse shock, K 10/31/2011

6 Case II: Rack on isolators – multi-DOF and 11/7/2011

7 Case II: Rack on isolators – drop shock 11/14/2011

8 Case II: Rack on isolators – random vibration 12/05/2011

9 Case III: Chassis/PCB – shock 12/12/2011

10 Case III: Chassis/PCB – random vibration 1/09/2012

11 Case IV: Transit Case Analysis – MIL-HDBK-304 1/16/2012

12 Case V: Transit Case Analysis – Nonlinearity 1/23/2012

CLASS NOTES & SOFTWARE

• LuxCalc Tools v1.2.8 is available for download from NG ESL server.

• Class notes will be posted on Fridays downloadable from Luxea.com site.

www.luxea.com/seminars

Create an account to access the files and blog access.

In the name field, start with “NG” before your name, e.g., name: NG Keith Yi

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HOMEWORK

• Homework description is included in the class notes.

• Answer is posted every Thursday pm.

• Discussions and comments are encouraged through Luxea HW blog

www.luxea.com/blog

Blog

Announcements

5

Accessing Class Notes

6

• Login after the privilege is given.

• Move the mouse over to Services – Seminar.

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Case Study III

Module with Power PCB

Random Vibration analysis of a chassis with a CCA mounted with

isolators, exposed to C130h aircraft random vibration

Conduction-cooled 3U Compact

PCI PCB

PCB Assembly mounted to

housing with Wedge-lok

Housing mounted with or without

isolators

Analysis using LuxCalc Tools

Demonstrate the Effectiveness of

isolators in shock and vibration.

Modeling

8

Problem Statement – Evaluate the shock response of the PECU PCB

exposed to C130h aircraft random vibration.

Chassis (6.4” x 7.6” x 6.8”)

PCB (6.3” x 4.0” x 0.1”)

Isolators, Barry Control T22-AB-3 (K~160 lb/in each)

Model input • Chassis: m1= 8 lbs, K1 = 640 lb/in, 1 = 15%

• PCB: m2 = 1.5 lbs, K2 = (???) lb/in, 2 = 5%

PCB Modeling

9

Wedge-lok (fixed bc)

PCB description • 6.3” x 4.0” x 0.1” FR4 with four 1 oz. copper layers

• m2 = 1.5 lbs, 2 ~ 5%

• How to determine K2? From static deflection or natural frequency considerations

CPCI Connector (simply supported)

PCB K Estimate

10

Static load consideration • Handbook – plate with lateral load and deflection

Natural frequency • Handbook (or LuxCalc Plate frequency)

FK

m

Kfn

2

1 22 nfmK

Equivalent PCB Young’s Modulus (E)

11

Use of LuxCalc Board K Module

Fr4 fiberglass E = 2.7e6 psi

Copper E = 17e6 psi

Equivalent PCB E = 3.5e6 psi

t

tEEor

t

tkk

ii

eq

ii

eq

PCB Natural Frequency

12

Use of LuxCalc Plate Frequency Module

Boundary condition

Material and geometry data

Natural frequency = 334 Hz

inlbfmK n /114,173342)386/5.1(222

PECU on Isolators – RV Response

13

33.32

1~

in

out

PSD

PSDQ

Hz

gPSDout

2

11.0~

Hzm

Kf I 96.27

386/0.8

640

2

1

2

1~

)1(21.12

)96.27)(33.3)(01.0(

2~

gfQPSDG ninout

PECU Hard-mounted – K1 Estimate

14

Chassis base ~ 6.4” x 7.6” x 0.01” plate

Chassis assy: m1+m1 = 8 lbs, K1 = ?? lb/in, 1 = 5%

Model base as Simply Supported Plate

= 8/(6.4 x 7.6 x 0.1)=1.645 lb/in3

inlbfmK n /556,71.962)386/8(222

fn ~ 96.1 Hz

PECU Hard-mounted – RV Response

15

Chassis K1 = 7556 lb/in, 1 = 5%

Hz

gPSDout

2

15.198.0~

122.582.4~ gGout

PECU Hard-mounted – RV Response

16

Chassis: m1+m1 = 8 lbs, K1 = 7556 lb/in, 1 = 5%

Hz

gPSDout

2

98.0~

182.4~ gGout

Rough Comparison

17

With isolators

No isolators

fn (Hz) 28 96

(%) 15 5

Q 3.3 10.0

Grms 1.21 4.82 – 5.22

Luxea Inc. / Dunamis Tech Inc.

18 The presentation material is a proprietary property of Luxea & Dunamis Inc. Contact the company for appropriate distribution.

Transit Case Analysis: MIL-HDBK-304

Case Study IV

Connector in Transit Case

Transit drop analysis of a heavy payload in transit

case

36 inch drop shock per MIL-STD-

810F procedure IV

Packaged protected by Polyether

foams

MIL-HDBK-304 data and

procedures for analysis

Use of LuxCalc Tools Shock for

checks

MIL-HDBK-304 & LuxCalc Tools

Payload in Transit Case

Transit drop analysis of a package in transit case using

MIL-HDBK-304.

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