Vibration and Shock
Test Control Techniques

Course No. 194

(Course Outline shown below.)

For Whom Intended  Engineering or technical personnel involved in specifying, tailoring (e.g. MIL-STD-810E) and performing state-of-the-art random vibration and shock tests; those who obtain/analyze/review field and laboratory test data; and those who design/certify hardware/structures/instrumentation to meet dynamic environmental requirements. Members of the automotive, aerospace, aircraft, shipboard and weapons technical communities will benefit.

Brief Course Description  The objective of the first portion of the course (also available separately as Course 196, Digital Data Acquisition) is to provide participants with the knowledge required to specify, evaluate and use a wide variety of digital data acquisition systems in laboratory and field applications. Basic principles of sampling and digitizing theory are presented and reinforced with practical examples from everyday testing operations. Emphasis is placed on understanding the theoretical concepts through “mechanical feel” rather than mathematics.

Hardware discussions concentrate on performance capabilities and practical problems that arise in laboratory and field applications. Heavy emphasis is placed on new technologies and system concepts that will be available in the near future. The aim is to prepare participants to design and procure state-of-the art systems that will satisfy their technical requirements efficiently and economically.

Literature describing the latest available hardware will be used as examples of good (and bad) practice. Particular emphasis will be placed on critical evaluation of commercially-available hardware and software systems.

The second portion of the course is an overview of vibration-testing technology with emphasis on the practical everyday problems that are encountered in testing laboratories. Emphasis is placed on the basic principles of vibration hardware, control systems, and analysis techniques used for random, sine, and shock testing. Capabilities and limitations of available systems will be discussed.

This course presents an application-oriented approach to digital computer control of random vibration and shock testing on shakers and analysis of vibration and shock data. Complex mathematical concepts are reduced to graphic form for intuitive understanding. Illustrative examples from the “real world” are used throughout. Demonstration programs written in LabView are used during the course to illustrate the concepts. These demonstrations are available for download, free of charge. Students are encouraged to download the demonstration programs prior to class, and install them on a laptop computer they can bring with them to class and use to follow along with the instructor when the demonstrations are presented.

The course is presented as a series of highly-interactive lecture/discussion sessions. Problems for individual and group solution are interspersed throughout the course to act as training aids and to evaluate class progress. Special-interest discussions are encouraged outside of the regular course sessions.

Prerequisites  Participants should previously have participated in TTi's Fundamentals of Vibration course, or in training offered by vibration equipment manufacturers, also TTi course 163, Instrumentation for Test and Measurement, or equivalent training. In addition, it would be helpful if participants have some experience in specifying and/or conducting computer-controlled tests on shakers and some exposure to spectrum analysis.

Certificate Programs  This course is required for TTi's Dynamic Test Specialist (DTS) Certificate Programs. It is an elective for any other TTi specialist certificate program

Text  Each student will receive a course workbook, including most of the viewgraphs used in the course presentation.

Course Hours, Certificate and CEUs  Open courses meet seven hours per day. Upcoming presentation dates can be found on our current open course schedule. Class hours/days for on-site courses can vary from 14-35 hours over 2-5 days as requested by our clients. Upon successful course completion, each participant receives a certificate of completion and one Continuing Education Unit (CEU) for every ten class hours.

Course Outline No. 194

Part I, Digital Data Acquisition

(Also available separately as Course 196)

• Overview of the Measurement Process — The System Approach
  • The role and function of digital data acquisition.
  • Testing and experiment types — what capabilities are required?
  • Accuracy, Dynamic Range, Headroom
• Basic Concepts
  • Basic calculations
  • The Fourier Transform as a “Black Box”
  • Data presentation in time and spectral domain
• Sampling and Digitization Theory
  • Data acquisition speed and accuracy/resolution considerations
  • Aliasing (download TTi's Aliasing Demonstration program)
  • Noise and other data corruption problems
• Data Acquisition Hardware
  • Signal Conditioning
  • Amplifiers
    • Common-mode rejection
    • Transducer wiring practice
  • Anti-alias filters
    • Estimating aliasing errors for different filter types
    • Filter/Sample-rate tradeoffs
  • Sample-and-hold amplifiers
  • Multiplexers
  • Analog-to-digital converters
    • Flash, Successive-approximation, Multi-pass, Sigma-Delta, Integrating
• The Computer System
  • Candidate computer systems — tradeoffs
  • Interface concepts — speed, implementation ease and robustness
  • Data storage — speed, volume considerations
• Types of Digital Acquisition Systems
  • Applications, Special considerations, Performance and limitations of available system architectures
• Data Analysis
  • Engineering-Unit Conversions
  • Data Interpolation
  • Correction of Anti-Alias filter distortion
• Evaluating Data Acquisition Systems
  • Simple tests to evaluate system accuracy/capability
• Specifying a system
  • How do you specify a system to get what you want?

Part II, Vibration and Shock Test Control Techniques

• Introduction and Basic Concepts
• Structural Resonances, Time History and Spectral Analysis
• Test Objectives and Philosophy
  • Damage Potential
  • MIL-STD Testing
• Environmental Simulation Concepts
  • Sine, Random, and Simulated Shock Excitation
  • Vibration and Shock History Reproduction
  • Test Specification
• Simulation Methods
  • “Programmed” Excitation
    • Excitation Hardware
      • Electrodynamic and Electrohydraulic Shakers
      • Specifications and Real-World Behavior
    • Excitation Functions
  • “Impact” and “Drop” Machines
• Fixtures
• Simulation “Accuracy” using different approaches
• Measurement Systems
  • Transducers for Vibration and Shock
• Data Acquisition Requirements and Methods
• Analysis Tools
  • Averaging Concepts, Degrees of Freedom
  • Power Spectral Density (PSD) and Shock Response Spectrum (SRS)
• Control Systems
  • Closed-Loop Control Concepts
    • Random Control
      • Spectral Control
      • Response and Force Limiting
    • Sine Controllers
    • Shock Synthesis and Control
  • Real-World Systems
    • System Demonstration — videos
    • System/Physical/Method Limitations
    • What do the Control Parameters Mean?
    • How do they effect the results?
• Multiple-Degree-of-Freedom Systems
  • Hardware Implementation
  • Control Strategies
• Random Vibration for HALT, HASS and ESS applications
• Review of currently available hardware
• Real-World Test Laboratory Applications
• Final Wrap-up
  • Student Topic/Problem Discussion
  • Review and Final Examination
  • Award of Certificate for Successful Completion

For schedules, enrollment information and more, visit http://www.ttiedu.com.