What is Impulse Excitation Technology
In this article, we will discuss the principle of impulse excitation, the equipment required, the test procedure, and the data analysis process.
Impulse excitation is a non-destructive testing (NDT) technique used to measure the elastic modulus, damping coefficient, and other mechanical properties of materials. It is a simple and quick technique that involves striking a specimen with a small hammer and then measuring the resulting vibrations using a transducer. This technique is widely used in quality control, materials science, engineering, and industry to characterize the mechanical properties of objects and materials.
The principle of impulse excitation is based on the fact that each object has natural frequencies of vibration that are related to its mechanical properties. When an object is struck with a small hammer, it will vibrate at its natural frequencies. The vibrations can be measured using a transducer, and the resulting data can be used to calculate the elastic modulus and damping coefficient of the material or to capture an object’s resonance fingerprint.
The equipment required for impulse excitation testing includes a small hammer, a transducer, and a data acquisition system. The hammer should be small enough to provide a localized impulse without damaging the sample. The transducer should be sensitive enough to measure the vibrations accurately. The data acquisition system should be capable of capturing and analyzing the data in real-time.
The impulse excitation test is a simple procedure that involves the following steps:
- Mounting of the specimen: The specimen is mounted on supports that allow it to vibrate freely in one or more directions.
- Striking the specimen: The specimen is struck with a small hammer to generate vibrations.
- Measuring the vibrations: The vibrations are measured using a transducer, which converts the mechanical vibrations into an electrical signal that can be analyzed.
- Data analysis: The data is analyzed to determine the natural frequencies of vibration, which can be used to calculate the mechanical properties of the material or to capture the object’s resonance fingerprint.
GrindoSonic devices follow the ASTM E1876-22 measurement standard.
The data obtained from the impulse excitation test can be analyzed using various methods, including the resonance frequency method, the time-domain method and the half-power bandwidth method. The resonance frequency method involves measuring the frequency at which the maximum amplitude occurs. The time-domain method involves analyzing multiple resonance frequencies and the half-power bandwidth method involves measuring the width of the frequency response curve at half the maximum amplitude, analyzing the damping characteristics of the object. All these data points can be combined forming the object’s resonance fingerprint.
The mechanical properties that can be calculated from the data include the elastic modulus, damping coefficient, Poisson’s ratio, and shear modulus. These properties are important in the design and analysis of materials and structures. The object’s resonance fingerprint can be used to compare the object to a database of good and bad objects for accurate quality control.
Impulse excitation is a simple and quick non-destructive testing technique used to measure the mechanical properties of materials. It is widely used in quality control, materials science, engineering, and industry to characterize the properties of materials and objects. The technique involves striking a specimen with a small hammer and then measuring the resulting vibrations using a transducer. The data obtained from the test can be analyzed to determine the elastic modulus, damping coefficient, Poisson’s ratio, and shear modulus of the material. Impulse excitation is an important tool for materials characterization and can help to improve the performance and reliability of materials and structures.