An increasing number of industries, from automotive to aerospace, are using vibration test to improve the design of their product and increase their yield. To accommodate the wide range of needs, vibration test manufacturers offer a variety of test-system configurations.
For example, a sinusoidal, single-axis test system based on the Japanese Industrial Standards shakes products designed for use in maritime, automotive, and consumer electronics products, said Dr. Paul Ibanez, president of ANCO Engineers. The system performs life testing of components or stress screening for defective electronic assemblies.
The test criteria for the single-axis tests often are discrete frequency/amplitude dwell intervals or constant-displacement amplitude sine sweeps from 2 Hz to 200 Hz, said Mr. Ibanez. The tests can be conducted with simple hardware and a drive system, such as a variable-speed eccentric cam system.
The dual-axis vibration system is a viable solution for companies that need spectrum control over their tests and want to minimize over- and under-stress conditions on products, said Robert Turner, president of Environmental Screening Technology. The spectrum-control function provides a capability of notching discrete frequencies to minimize the bending mode of a PCB during screening.
Highly accelerated life testing which provides vibration in three axes and three rotations, a wide test frequency range, and a high level of energy is being implemented by some companies. Such a system often combines thermal and vibration equipment to ensure that maximum energy is transmitted to all components, regardless of orientation or resonant frequency, said Neill Doertenbach, technical product manager at QualMark. Users of these systems want vibration levels from 50 to 60 g rms in the 2-Hz to 5-kHz frequency range.
For product screening operations, the high vibration levels are not as important because you do not want to take the product to failure, said Mr. Doertenbach. A key requirement for production screening is ease of fixturing and simple product handling.
Today, most challenges for environmental test manufacturers come from the automotive and telecommunications industries. Car manufacturers need customized, automated environmental test stations that suit specific car models, said Sri Welaratna, president and CEO of Data Physics. For example, Data Physics adapted a system that automated a customer’s fatigue testing of critical components.
There also is keen interest in collecting vibration data from the field and performing controlled tests in a lab. Many users want to reproduce the collected acceleration time data using an electrodynamic shaker with closed-loop control, said Joseph Testa, applications engineer at Unholtz-Dickie. This type of system can support acceleration time-history testing to 500 Hz.
Previous testing methods for controlled simulation in a lab vibrated complete automobile structures using complex configurations of hydraulic actuators that operated in conjunction with expensive mainframe computers. These tests typically were limited to <100 Hz using a type of open-loop control.Whatever method you use to check the quality of your product, some form of vibration test can help improve your design and product yield. Now all you have to do is decide which test system is best for your product.
Vibration Test Products
Single-Axis Table
Supports 1,200-lb Payload
The R-SSA Single-Axis Sinusoidal Tables are actuated by PLC-controlled, variable-speed motors. The tables support payloads from 12 lb to 1,200 lb at a frequency range from 2 Hz to 200 Hz. Table sizes are available from 1.0 ft2 to 10 ft2. Peak displacement is continuously variable to ±3/4″. Included sine and sine-sweep waveforms provide the capability to repeat a sine dwell/sweep pattern many times. ANCO Engineers, (800) 932-5515 ext. 239.
Enhanced Software Offers
Fatigue/Production Testing
The DP550Win Version 3.0 Vibration Control Software offers fatigue testing in sine control, an enhanced production test set in shock and transient, and SRS testing for compliance with the Bellcore standard for earthquake, office, and transportation vibration. Also included are improvements in random control to detect open-loop conditions during self-test. Connectivity across a network is simplified so you can make your own interface elements and interact with the DP550Win SignalCalc Vibration Controller from a remote location. Data Physics, (408) 371-7100.
Dual-Axis Vibration System
Runs 18-lb Payloads
The VH5 Dual-Axis Vertical/Horizontal Vibration System has an in-line mounting surface which can be used for robotic-loading and conveyor production applications. It runs payloads of 18 lb to 6 g rms in both axes simultaneously. The system features random spectrum control and shaping from 20 Hz to 3,000 Hz, a 14″ × 14″ product mounting platform, and a continuous loop-tape random-generation function. Environmental Screening Technology, (616) 772-5485.
HALT System Designed
For Small Products
The OVS-1.5 Highly Accelerated Life Test (HALT) System combines an 18″ × 18″ vibration table into a small system footprint. It provides a maximum of 80 g rms and thermal change rates up to 60° per minute. The system uses 208-VAC power and can operate with portable liquid nitrogen tanks. The chamber requires an air supply of 20 scfm for maximum vibration conditions. QualMark, (303) 254-8800.
Controller Features
Multi-segment Tests
The Model 2050A Multi-Tone Vibration Controller supplies sine excitation and control for electrodynamic and hydraulic shaker systems requiring input frequencies from 1 Hz to 20 kHz. The sine tones can be divided into 25 frequency segments to provide a specific vibration profile. The segments control acceleration, velocity, or displacement. Servo compression speed is programmable in the sine profile from 1 dB/s to 250 dB/s. Linear sweep rates in hertz per second and logarithmic sweep rates in octaves/min are provided. Trig-Tek, (714) 956-3593.
Closed-Loop Control Software
Puts Data in Time Domain
Time Replication Acceleration
January 1998