Shock and Vibration Testing
Agenda Shock Testing Vibration Testing Comparison and Selection of Methods Comparison of Specs Rationale for Selection of Testing Vibration Testing Rationale for Selection of Testing.
Vibration and Shock
Vibration and Shock Machine Type Range Capabilities TIRA Vibration 20,000lb vector, 2 inch displacement 5-2500Hz 3 axis slip plate; 5 ft. x 5 ft. slip table 12,000lb vector, 2 inch displacement 3 axis slip plate; 30 in. x 30in . slip table Unholz Dicke 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 6000lb vector, 1 inch displacement 5 – 3000 Hz Ling 5 – 2000 Hz 3 axis slip plate; call for size limitations Thermotron 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 30,000g’s/0.02ms Schaevitz G-6-A Acceleration Limited by 3 ft. arm; Call for size
Vibration and Shock
Vibration and Shock Heating Elements HALT Test Vibration Impactors
Vibration and Shock 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 without damaging the product or reducing its life. HALT/HASS Chamber
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 windows
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 SRS
Vibration and Shock Drop Shock Sawtooth, Half-Sine
Classical Shock Test Machines
Vibration and Shock High G Mechanical Shock
Vibration and Shock High G Constant Acceleration
Vibration and Shock
Fatigue Crack Growth
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 Most damage occurs at fundamental frequency of electronics PCB.
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 less than 1,000 cycles.
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? Follow the Contract Specifications Create Your Test Based on Existing Specifications as Guidance Make Field Measurements
1- Follow Contract Requirements
Contract Requirements MIL-PRF-15305
Contract Requirements MIL-PRF-15305 MIL-STD-202G Method 213
2- Use Existing Specifications for Guidance Military, Regulatory, and OEM Specs Industry Standard Test Methods with Recommended Levels Create Your Own Specification
Shock Test Specs & Methods Automotive FORD, GM SAE J1455 Commercial Products IEC 68-2-27; -29; -31 Commercial Aviation 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 Classical Pyroshock Ballistic Shock
Handling and Free Fall Drop Tests Drop Surfaces Concrete Steel Wood Sand Package or Device
Typical Classical Shock Tests for Electronic Systems
Typical Classical Shock Tests for Electronic Systems- IEC 68-2-27
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) Short Pulse 0.5msec 150Gs Long Pulse 30msec 15Gs
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 Does not evaluate device response to shock
Classical Shock Tests
Classical Shock Tests
Shock Response Spectrum
Shock Response Spectrum Input Pulse Measured Response
Shock Response Spectrum
Shock Response Spectrum
Shock Response Spectrum
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 Pyrotechnic Shock
Pyrotechnic Shock
Pyrotechnic Shock
Pyrotechnic Shock
Ballistic Shock
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. MIL-810 Fragility Test
Vibration and Shock Summary Follow the Contract Specifications Create Your Test Based on Existing Specifications as Guidance Make Field Measurements Call us with your application needs.
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