Abstract
The development of new sensors that are available at more accessible prices may lead to the spread of their use on common studies in structural dynamics. One of areas of interest is the experimental determination of rigid body properties that are mandatory when the vibration response is to be calculated at low frequency ranges. In this work, a comparison of the experimental determination of rigid body properties is carried out to evaluate the performance of the commonly used tri-axial piezoelectric accelerometers and their equivalent MEMS sensors. Although their prices are quite different, both sensors can measure the inertia restraint line that is related to the inertia properties of the tested object. An identification algorithm is applied to the frequency response functions obtained by using both sensors, leading to the estimation of the body mass value, as well as the three coordinates of the centre of mass and the six elements of the inertia tensor. An experimental example supports the use of the referred low-cost sensors.
Highlights
Whenever the dynamic behaviour of a structure at very low frequencies is important, the ten rigid body properties of a mechanical system is of vital importance. These rigid body properties are mass, position of the centre of mass and inertial moments and they may be estimated using numerical or analytical approaches or using experimental driven procedures. The latter have been addressed by several authors [1,2,3,4,5,6,7,8,9,10], considering different methods that can be divided into two main categories: Frequency domain methods [1,2,3,4,5] and Time domain methods [6,7]
The methods based on the Frequency domain are mainly divided into three groups: Inertia Restraint methods (IRM) [1,3], Methods of Direct Physical Parameter Identification [2] and the Modal methods (MM) [4, 1114]
The authors focused their attention on the use of IRM or the so-called Mass Line methods (MLM) that are based on the principle that the dynamic response of structures in free-free conditions are characterized, in the low frequency region, by a constant term designated as inertial restraint or mass line
Summary
Whenever the dynamic behaviour of a structure at very low frequencies is important, the ten rigid body properties of a mechanical system is of vital importance. The authors focused their attention on the use of IRM or the so-called Mass Line methods (MLM) that are based on the principle that the dynamic response of structures in free-free conditions are characterized, in the low frequency region, by a constant term designated as inertial restraint or mass line. This approach is suitable for structures where rigid and flexible modes are well separated.
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