Shock and Vibration Testing

Agenda



Shock Testing



Comparison and Selection of Methods

 Comparison of Specs

 Rationale for Selection of Testing



Vibration Testing



Comparison and Selection of Methods

 _{Comparison of Specs}

Vibration and Shock

Machine Type Range Range Capabilities

TIRA Vibration

20,000lb vector, 2 inch

displacement 5-2500Hz

3 axis slip plate; 5 ft. x 5 ft. slip table

TIRA Vibration

12,000lb vector, 2 inch

displacement 5-2500Hz

3 axis slip plate; 30 in. x 30in . slip table

Unholz Dicke Vibration

17,000lb vector, 1.5 inch

displacement 5 – 2500 Hz

3 axis slip plate; 36 in. x 36 in. slip table

MB Corp Model

C-60 Vibration

6000lb vector, 1 inch

displacement 5 – 3000 Hz

3 axis slip plate; 30 in. x 30in . slip table

Ling Vibration

6000lb vector, 1 inch

displacement 5 – 2000 Hz

3 axis slip plate; call for size limitations

Thermotron Vibration

5 Hammer Repetitive

Shock 5-20,000 Hz

HALT Thermal Shock with vibration

Elite

Package

Vibration 2 – 4 Hz

Cam operated bounce test for transportation

AVCO FF367-1

Mechanical

Shock 300g’s/20ms Inquire Sine or saw-tooth AVCO A105

Mechanical

Shock 30,000g’s/0.02ms Inquire Sine or saw-tooth Schaevitz G-6-A Acceleration

Vibration and Shock

HALT Test Vibration Impactors

Vibration and Shock

HALT/HASS Chamber

HALT -Highly Accelerated Life Testing

•Combined six-axis vibration and temperature extremes.

•Intentionally but systematically produces test item failures for the purpose of rapidly identifying mechanical, electrical, design and functional

weak points.

•Design weaknesses can be analyzed,

corrected, and the product design optimized.

HASS -Highly Accelerated Stress Screening

•Overstress test to identify marginal or defective products before shipment.

•HASS test levels are identified during HALT and are established to compress test time

Vibration and Shock

 Elite HALT/HASS Chamber Capabilities  -100C to +200C (-148F to +302F)

 Greater than +70C per minute product temperature change

rates (heating or cooling)

 30” x 30” Vibration Table, 480lbs total weight capacity for test

item & fixture

 Workspace Dimensions 42”W x 42”D x 40”H

 Vibration Frequency Range: 2Hz-10kHz; Vibration Level: Up

to 50Grms

 Two (2) 3”x8” access ports, Three (3) 20”x20” viewing

Vibration and Shock

Vibration Testing

Sine, Random, SOR, Field Data Replication

•Record actual vibration levels •Import data to vibration controller

•Operate vibration table according to recorded profile and acceleration magnitude

• Run test item for endurance •Mechanical Shock

Vibration and Shock

Drop Shock

Vibration and Shock

Vibration and Shock

Vibration and Shock

Sine Vibration

From rotating or oscillating

machinery; electric motors,

wheels, engines, gears, springs.

Useful for evaluating dynamic

characteristics of structures, i.e resonance

Random Vibration

More accurately represents the

true environment.

Excites all frequencies

Vibration and Shock



Shock

 High stresses causing fracture or permanent deformation  High accelerations which can cause relays to chatter,

potentiometers to slip, bolts to loosen.

 High displacement which can cause impact between

adjacent circuit boards

 Usually not considered a fatigue failure if shock quantity

Selecting a Vibration Level or a Shock Pulse



Which Shock Pulse should I Apply?



How Many?



Which Level?



What is the vibration spectrum of interest?



How long should I test for?

1.

Follow the Contract Specifications

2.

Create Your Test Based on Existing Specifications

as Guidance

Contract Requirements MIL-PRF-15305

2- Use Existing Specifications for Guidance



Military, Regulatory, and OEM Specs



Industry Standard Test Methods

 with Recommended Levels

Shock Test Specs & Methods

 RTCA DO 160E Section 8

 _Military

 MIL-STD-810 Systems

 MIL-STD-883 Circuit Cards  MIL-STD-202 Components

Handling Drop

Classical Shock (Potholes & Crashes) Classical Shock

Bump Free Fall

Operational and Crash Safety Shock Sustained Shock

SRS

Typical Classical Shock Tests for Electronic Systems

MIL-STD-810F Ground Equipment 75g-6ms Saw-tooth 3 pulses x 3 axes x 2 Dir (18 total)

ISO 16750-3 50g-6ms Half-Sine 10 pulses x 3 axes x 2 Dir (60 total)

General Motors GMW 3172 25g-15ms Half-Sine 132 pulses x 3 axes x 2 Dir (792 total)

General Motors GMW 3172 100g-11ms Half-Sine 3 pulses x 3 axes x 2 Dir (18 total)

Ford Motor 100g-10ms Half-Sine 6 pulses x 3 axes x 2 Dir (32 total)

RTCA DO-160D (Operational) 6g-11ms Saw-tooth 1 pulse x 3 axes x 2 Dir (6 total)

RTCA DO-160D (Crash Safety) 20g-11ms Saw-tooth 1 pulse x 3 axes x 2 Dir (6 total)

A(Gs)

Time (msec)

A(Gs)

Typical Classical Shock Tests for Electronic Systems-

Gs Time Wave Components Equipment

General handling and transport.

Land based items or items transported by road, rail or air in secured shock resistant packages

30 18 ST, HS, TR

Installed or tranported in a secured position on normal road or rail vehicles or in transport aircraft

500 1 HS

Structural integrity tests on

semiconductors, integrated circuits, microcircuits.

1500 0.5 HS

Structural integrity tests on

semiconductors, integrated circuits, microcircuits.

ST, HS, TR 6

100

Items installed or transported in a secured position in full cross-counry vehicles. Items carried loose in normal

road or rail vehicles for long periods. Items used in industrial areas and subjected to shock from mechanical handling equipment for example dock

cranes, fork lift trucks.

Items in secured packages transported by full cross country

vehicles. Items mounted in equipment tranported by or installed

in full cross country vehicles or aircraft

Items in secured packages transported by wheeled vehicles, aircraft, merchant ships or light

marine craft. ST, HS, TR

11 30

Elite Capability for Classical Shock

 Large Avco (Assume 150lb load and fixture)

 Short Pulse 3msec- 300Gs  Long Pulse 30msec-20Gs

 Small Avco (Assume 50lb load and fixture)

 Short Pulse 0.3msec- 1000Gs (longer pulses up to 10kGs)  Long Pulse 6msec-500gs

 Tira Electro-dynamic Vibration Table (Assume 150lb load and

fixture)

Classical Shock Pulses

Advantages

 _{Easy to specify and understand}  shape, tolerance, mathematics

 Test machinery can generate pulses

 Accepted methods written into many specs



Disadvantages

 Not real world pulses

Classical Shock Tests

Engine 3.sif - [email protected]_2

Axis3(g's) -20-15 -10-5 0 5 10 15

Engine 3.sif - [email protected]_2

Axis2(g's) -15 -10-5 0 5 10 15

Engine 3.sif - [email protected]_2

Shock Response Spectrum

Input Pulse

Shock Response Spectrum



Preferred method for MIL-810



Describes the Peak Acceleration Response vs.

Freq



Develop a simple shock pulse that will generate the

response function



Some ED shakers have SRS capabilities



Ringing plates

Custom Shock Evaluation



ASTM D3332



Damage Boundary



Response to short duration pulse is a

function of velocity change.



Response to long duration pulse is a function

of the peak acceleration and waveform.

Vibration and Shock Summary

1.

Follow the Contract Specifications

2.

Create Your Test Based on Existing

Specifications as Guidance

3.

Make Field Measurements