# Enhancing Vibration Analysis in Hydraulic Presses: A Case Study Evaluation
## 2 State of the Art
It is relatively easy to detect vibrations resulting from kinematic excitation, i.e., those caused by the motion of a specific element (e.g., vibrations due to a vehicle moving on an uneven road), or dynamic excitation, i.e., due to the action of external forces on a specific element or forces resulting from the interactions of other components [28]. The magnitude of the force may change (periodically or non-periodically), or only its direction or point of application may change over time (e.g., centrifugal forces resulting from the rotational motion of an unbalanced mass). It is more difficult to detect self-excited vibrations, which are usually caused by varying frictional resistance, hydrodynamic and aerodynamic forces, or the occurrence of feedback and parametric vibrations, often caused by periodic changes in the stiffness of elements [29]. Determining the variation of loads under the influence of vibrations allows for the assessment of stresses and deformations resulting from external forces and inertial forces. By measuring the forces and moments occurring at load application points, connection points, etc., it is possible to obtain the dynamic load profile of individual elements of the object [30]. Vibration measurements enable the examination of the impact of dimensions and shapes of elements (and thus masses, stiffness, etc. ), mounting methods, and materials in vibration parameters. Vibrations of objects, except in vibration engineering systems, are detrimental [31]. They disrupt the proper functioning of equipment, leading to rapid wear and energy loss. If vibrations occur, efforts are made to identify and locate their causes, followed by mitigation. If vibrations cannot be reduced, isolating elements are employed to dampen them. The advancement of technology in recent years has revolutionized the field of vibration monitoring in industrial machinery, including hydraulic presses [32; 33]. Traditional methods of monitoring vibration relied on rudimentary sensors and limited data analysis capabilities, often providing only a partial understanding of machine health [34]. During the operation of a hydraulic press that performs specific work functions, undesirable phenomena appear that negatively affect the operation of the machine. One of the common undesirable phenomena is the vibration of machine body elements. In the case of hydraulic presses, these vibrations lead to deterioration in the quality of the pressed element and faster wear of the machine, causing more defects and the associated higher production costs. Increasing the resistance of the press to the vibrations (vibrostability) of body elements is possible and is already in the prototype stage [35]. One of the most frequently used methods for measuring the dynamic characteristics of hydraulic presses is the measurement method using accelerometer sensors. Such measurements are usually carried out under the control of specialized computer measurement systems, such as the CADAX system from LMS. A counterbalance to this type of measurement is research using laser scanning vibrometers. Laser vibrometry has a number of advantages over traditional measurements with accelerometer systems. The biggest of them are no influence of the measurement system on the measured object (non-contact measurement) and a relatively simple measurement procedure (does not require the time-consuming rearrangement of sensors on the measured object) [36]. However, with the advent of advanced measurement systems equipped with high-resolution accelerometers and sophisticated data processing algorithms, engineers now have access to more comprehensive and accurate vibration data. These systems offer multi-axis vibration measurement capabilities, allowing for a detailed analysis of machine dynamics in real-time [37]. Furthermore, the integration of data acquisition units with Ethernet communication interfaces has facilitated remote monitoring and the control of vibration parameters.