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Measurement Testing
A Resource Dedicated to Environmental Testing, EMC Testing, Vibration Testing and related areas
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Mjr
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Joined: 13 Jul 2005
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 Posted: Sun Dec 25, 2005 6:20 am Post subject: TTi's Fundamentals of Vibration for Test Applications |
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TTi's Fundamentals of Vibration for Test Applications:
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Applications Random vibration and shock are important in most engineering applications where the product is exposed to transportation and to possible vibration and shock during service. The need to understand the effects of vibration and shock on product reliability is paramount today, where electronic/computer components are part of almost every product.
For whom intended Many engineers need specialized education to properly measure, quantify, and analyze this generally unfamiliar environment and to reproduce it in environmental test laboratories. This course is for test laboratory managers, engineers and technicians. It also helps quality and reliability specialists and acquisition personnel in government and military activities and their contractors. It is designed to serve the needs of personnel in a wide range of industries where equipment problems may be encountered during the shipment and use of their product.
The instructor maintains good balance between theory and practical applications. Instrumentation specialists who will measure transportation, service, and laboratory vibration need this course. Metrologists learn about vibration the use of sensors. Project personnel, structures and packaging engineers learn about developmental testing. Product assurance and acquisition specialists learn to evaluate test facilities and methods, and to interpret specifications.
Brief course description This course is the initial course in TTi's environmental engineering specialist program. It covers a wide range of topics associated with vibration and shock applications in order to enable the course participants to acquire a basic understanding of the complex field of vibration and shock. Each of the subject areas covered in this course have expanded coverage in their own three day courses for those individuals who need a more thorough understanding for their application.
Lectures and videotaped physical demonstrations show for example: how structures behave when mechanically excited, how to use pickups to sense input and response forces and motions, how to read out and evaluate the resulting electrical signals.
The course commences with an introduction to vibration and its effects and then proceeds to cover the basic theory needed to understand the material covered during the three days. While mathematics are kept to a minimum, it is necessary to cover a sufficient amount so that the concepts of vibration can be understood. The course presents some basic theory of electronic filters and measurement systems.
The theory of dynamics is covered, including the relationships between displacement, velocity and acceleration, and then the various types of vibration exciters are discussed. Random vibration theory and the concept of test fixtures and vibration measurement are discussed before proceeding to cover vibration testing, mechanical shock applications and environmental stress screening, as well as HALT and HASS applications.
Video demonstrations show effects of sinusoidal and random vibration. Control for sinusoidal and random vibration tests are discussed. Derivation, application, and interpretation of test specifications are debated. Classroom and nightly review problems measure progress (bring an electronic calculator to class). |
Here is the Course Outline (Course No. 116)
Introduction to Vibration Design and Testing for Vibration and Shock, Prolonged Excitation of Natural Frequency
Understanding Decibels (dB) and Octaves Decibels, Power Ratio, Voltage Ratio, dB Ratio Conversions, Logarithmic vs. Linear Scaling, Sound Perception, Octaves
Electronic Filters and Measurement Systems Integrating and Differentiating Circuits, Filtering, Low-pass, High-pass and Bandpass Networks, Bandpass Filter Shapes, Sine Waves, Understanding RMS, Complex Signals, Random Signals
Dynamic Force and Motion Laws of Motion, Weight vs. Mass; Weight, Mass and Gravity; Force, Mass and Acceleration; Stress-Strain Relationship, Work, Power, Energy, Fundamentals of Dynamics, Simple Dynamic System, Degrees of Freedom, Undamped Vibration, Calculating Natural Frequency, Harmonic Waves, Radians, Relationship between Displacement, Velocity and Acceleration, Single Degree of Freedom — Forced Vibration, Transmissibility, Isolation, Damping, Critical Frequencies, Vibration Considerations for Design Engineers, Using a Vibration Slide Rule
Vibration Exciters (Shakers) Mechanical Shakers, Electrohydraulic (EH) Shakers, Electrodynamic Shakers, Force Rating and Available Acceleration, Displacement and Velocity Limits of Electrodynamic Shaker, Piezoelectric Shakers, Extending Table Diameter, Table (Head) Expander, Horizontal Accessory — Oil-Slip Tables, Combined Environmental Reliability Testing (CERT) Vibration Testing, Stroke vs. Frequency Range
Random Vibration Sinusoidal Vibration, Complex Waveform, Random Vibration, "Single Sweep" Time History, Effects of Random Vibration, Definitions, Power Spectral Density, Equalization to Correct PSD, ESS Random Vibration Spectrum, Example of Vibration Spectrum, Developing Total RMS from Spectral Plot, Transmissibility Derived from Random Vibration.
Test Fixtures Purpose of a Fixture, Basic Considerations, Fabrication Methods, Typical Machined Fixture, Evaluating Fixtures, Fixture Weight Relative to Test Item Weight, Orthogonal Motion in Sinusoidal System, Shaker Crosstalk, Design Criteria
Vibration Measurement The Ideal Transducer, Velocity Sensing, Optical Wedge for Estimating Displacement, Displacement Sensor, Strain Gages, Silicon Semiconductor Transducers, Measuring Displacement, Velocity Sensors (Pickups), Piezoelectric (PE) Accelerometers, Mounting Methods, Signal Conditioning, Charge Mode Sensors, "Charge" Amplifiers, Internal-electronic Systems
Power Amplifiers, Effects of Resonance Harmonic Distortion, Non-Linearity Distortion, Power Amplifier Block Diagram, Shaker Armature Electrical Resonance, Effect of Mechanical Resonant Loads
Vibration Testing Types of Testing: Development, Qualification, Acceptance, Screening, Reliability, Life; What is the Environment, Philosophy of Vibration Testing Control, Closed Loop Control, Function Generators, Location of Control Accelerometer, Unwanted Table Movement, Resonant Distortion of Electrodynamic Shaker Table, Shaker Slip Tables, Shaker Control-Input or Response, Notching, Strobe Light used with Sinusoidal Vibration Test, "S-N" Curve from Fatigue Testing, Accelerated Vibration Testing — Proceed with Caution Multiple Degrees of Freedom Testing, Multi-Axis System, Simultaneous 3-Axis Testing, "Real" Multiple Degree-of-Freedom System, "Tri-Axial Quasi-Random" Systems, Two-Shaker, Three-Degree-of-Freedom Systems
Basics of Spectral Analysis Mechanical Vibration Analyzer, Why Use the Frequency Domain?, Phase of Frequency Domain Components, Time and Frequency Domain, Spectral Analysis, Fourier Transforms, Fast Fourier Transform (FFT), Spectrum Analyzers, Power Spectral Density... PSD, Transfer Functions, Data Acquisition, Aliasing in Frequency Domain, FFT Distortion, Windowing, Filters
Sine Vibration Testing Closed Loop Control, Sine Sweeps, Effect of Sweep Speed, Resonant Search, Plotting Acceleration vs. Frequency, Velocity vs. Frequency and Displacement vs. Frequency, Vibration Nomograph.
Random Vibration Testing Calculating RMS from PSD, Gaussian Random Signal, Standard Deviation, Statistical Degrees of Freedom, Random Vibration Control, Block Diagram of Random Vibration System, Actuator System, Transfer Function, Response Spectrum, Tickle Test, Sine on Random tests, Random on Random tests, Overtest Protection, Random Vibration Test Spectrum "Walkthrough" of an Imaginary Test
Mechanical Shock Causes of Shock, Effects and Remedies of Shock, Transient or Shock Tests, Shock Pulses, Shock Testing on various types of Machines, Table-Top Drop Shock Test, SRS in Shock Testing, Fourier Spectrum Analysis, SRS vs. Fourier Analysis
Environmental Stress Screening Exponential Failure Model, ESS vs. Test, ESS Objective — Remove Flawed Equipment, Screening (or Testing) ESS Process Plan, Typical ESS Process Flow Chart, Thermal Environments, Vibration Environment, Step Stress Tests, Highly Accelerated Stress Screening and Life Testing (HALT and HASS)
Standards vs. Specifications Why standards and specifications are needed, Prominent Standards
Final examination
Award of certificates for successful completion
For more information, contact: http://www.ttiedu.com/ |
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