Fundamentals of Random Vibration and Shock Testing: HALT, ESS, HASS Measurements, Analysis and Calibration

Date and Time
Dates and Locations TBA

Instructor
Wayne Tustin

Course Description

Discussion, supported by projected visuals and video clips. Commencing with a review of basic vibration sources and causes, we will explore vibration measurements, analysis and calibration. We’ll compare sinusoidal vs. random vibration testing systems, specifications, standards and procedures. We will discuss ESS, HALT and HASS. We’ll emphasize vibration and shock test fixture design, fabrication, experimental evaluation and usage. Also shock measurement, shock response spectrum (SRS) and shock testing. Review of modal testing. We emphasize topics you will use immediately.

Today and in the near future we protectively install commercial-off-the-shelf (COTS) equipment in our flight, land vehicles and shipboard locations where vibration and shock can be severe. We laboratory test the protected equipment (1) to assure twenty years equipment survival and possible combat, also (2) to meet commercial test standards, IEC documents, military standards such as STANAG or MIL-STD-810G, etc. Few if any engineering schools teach about such protection or such testing. Hence this specialized course.

Objectives

After this short course, you will be able to

• measure vibration and shock,

• calibrate vibration and shock measurement systems,

• convert field measured data into a test program,

• interpret vibration and shock test requirements,

• supervise vibration and shock tests,

• specify and experimentally evaluate vibration and shock test fixtures,

• perform ESS, HALT and HASS.

When you visit a lab or review a test program, you will have a good understanding of the requirements and execution of a dynamics test and so be able to ask meaningful questions and understand the lab’s responses.

Who Should Attend

• I need practical knowledge about mechanical vibration and mechanical shock test, measurement, analysis, designing for dynamics also calibration and/or control because my work requires me to:

• I instrument land, sea and air vehicles as well as fixed-based equipment, in order to measure mechanical vibration and/or shock in service and during transport.

• I analyze dynamic responses to mechanical vibration and shock inputs during normal and abnormal transport.

• My title may be mechanical engineer, mechanical designer or packaging engineer. I design (ruggedize) products that must withstand factory handling + transport + normal and abnormal usage. I design products to dynamic requirements, which I don't fully understand. Then I send a prototype to our lab for testing. I really don't understand what our lab does. I'd better find out.

• I write contracts for procuring high-rel equipment. I need to understand HALT, ESS and HASS. When do these acronyms apply? How do I insure that potential contractors will appropriately implement the random vibration requirements of these acronyms? What is g2/Hz?

• I work in an environmental test lab. We perform vibration and shock tests on prototype hardware. These tests may be part of developing a new product, of determining vibration levels for future production ESS (environmental stress screening) or production tests, or of investigating in-service or transport failures.

• I calibrate various vibration and shock sensors (including accelerometers) and analyze vibration and/or shock.

• I design to control (reduce) the intensity of vibration and/or shock, which otherwise may damage equipment that cannot be made sufficiently rugged to survive all inputs.

• I maintain machinery whose vibration signature can warn of approaching failure.

If you thought, "aha - that's what I'm supposed to do" to any of the job descriptions listed above, then the instructor says, "This course is intended for you." It will help you move up your own "learning curve."

A smaller group, for whom the instructor also intends this course: supervisors of any of the above listed activities. Perhaps you were thrust into this responsibility without adequate training. Maybe your predecessor had no opportunity to alert you to potential difficulties. You certainly need to know what your people are talking about. Possibly you had no formal training for your present responsibilities. You need to explain your department's activities to your superiors in the technically correct language. Perhaps you need to decide between "in house" and "outside" testing.

Course Outline

Introduction for management and participants

• Purpose of environmental testing, particularly vibration and shock
• Purpose of environmental stress screening (ESS)
• Types of vibration tests: resonance search/dwell, fatigue, specification

Quiz for evaluation of attendee prior knowledge

Classical sinusoidal vibration never observed in service; useful concept

• Introduction: terminology, structural resonant behavior, passive and active isolation
• Sinusoidal vibration measurements: units, sensors, readouts, errors
• Calibration of sensors and systems; traceability to NIST

Most machinery vibration is complex; introduction to
spectrum analysis
Sinusoidal vibration testing

• Electrohydraulic and electrodynamic shakers; theory, tradeoffs, limits
• Power amplifier theory, operation, limitations, distortion effects
• Controls for sinusoidal vibration testing
• Sinusoidal vibration test practice
  • Interpretation of standards; e.g. MIL-STD-810
  • Controversial test methodology: tracking filters, switching and averaging among sensors

Introduction to random vibration

• Sources of random vibration in service and transportation
• No possible equivalence to sinusoidal vibration
• Terminology and definitions
• Spectral density measurement and analysis - the frequency domain. What is g2/Hz?
• Probability density - the time domain

Random vibration test practice

• Interpreting and implementing standards, e.g. MIL-STD-810
• Equalization before testing; methods and limits
• Controls
• Electronic protection for test items and shaker system
• Simultaneous multaxis vibration testing

Combined environment (CERT) testing; reliability tests, e.g. MIL-STD-781

Environmental stress screening (ESS) of electronics hardware production

• Single vs. multi-axis vibration
• Pneumatic repetitive-shock machines

Highly accelerated life testing (HALT), environmental stress screening (ESS) and highly accelerated stress screening (HASS) of electronics hardware production.

• Single vs. multi-axis vibration.
• Pneumatic repetitive-shock (RS) machines.
• Acoustic excitation of printed wiring boards (PWB).

Vibration and shock test fixtures; fixtures for stress screening

• Recommended designs, materials, fabrication methods
• Experimental evaluation before use
• Practical limits: transverse motion; specimen size and weight

Accommodating oversized loads

• Table expanders
• Slip plates and alternatives

Instrumentation for measuring shock in service and during tests

• Sensors, readouts, errors
• Calibration

Shock spectrum analysis; shock response spectrum

Shock testing standards and methods

Modal testing

Witnessing of tests

Course summary; optional final examination; award of certificates

Text Materials

Each participant receives a copy of Wayne's text 'A minimal-mathematics Introduction to the Fundamentals of Random Vibration and Shock Testing, HALT, ESS & HASS, also Measurements, Analysis & Calibration', including a CD containing a number of video clips pertaining to sine and random vibration and shock behavior and testing.

Fee/Registration

Fee is US$2,595 per student. Payment in advance via check, VISA or Mastercard preferred credit cards or bank transfer (ask for transfer details).

For registration and payment received one month prior to course, deduct $100. For three or more participants from an organization and payment received one month prior to course, deduct $200 each.

 

 

Suggestions for Accommodation
Hampton Inn 5311 Buckeystown Pike Frederick, MD (301) 698-2500 Hampton Inn Frederick	Extended Stay America 5240 Westview Drive Frederick, MD (301) 668-0808 Extended Stay America Frederick
Best Western - Historic Frederick‎ 420 Prospect Blvd. Frederick, MD‎ (301) 695-6200‎ Best Western - Historic Frederick