Vibration testing is an important linking process in product development and quality assurance between theory and practice. It imposes periodic mechanical loads on parts, assemblies, or the whole system to discover its vulnerabilities in a way that is not available to static testing methods. Its most important objectives are validation, compliance with specifications, and longevity of the product in the target range of operations, and verification, that is, the capability to work in the most stringent dynamic conditions without failure. Vibration testing is done on specialised equipment such as an electrodynamic or hydraulic shaker to give engineers insight into the life of products, design optimization, international standards, and to avoid disastrous failures that may result in expensive product recalls or safety problems in life-or-death products.
Fundamental Principles
The test is intended to discover resonance states in which the excitation frequencies coincide with the natural frequencies of the object and, therefore, the amplitude is dangerously amplified. It also causes material fatigue by cyclic stress loading to establish limit endurance and mimics real-world vibration profiles as recorded by real-world sources such as road surface, engine activity, or seismic activity.
Types of Vibration Tests
Random vibration tests use the continuous spectra of frequencies at the same time, and that is a simulation of the actual conditions in the real world, such as turbulent airflow or rough transportation, using the Power Spectral Density (PSD) profiles. Shock tests expose specimens to high-accelerating pulses (half-sine, sawtooth waveforms) that represent the effects of drops or explosions. Resonance search and dwell tests determine the critical frequencies and keep vibration at the frequencies to stimulate fatigue failures. Transportation simulation tests are based on field-recorded data of trucks, ships, or aircraft to generate custom profiles on which the packages are being tested.
