The dynamic characteristics of mechanical structures destruction

• Main Author: Henryk Kaźmierczak
• Format: Article
• Language: English
• Published: JVE International 2016-12-01
• Series: Journal of Vibroengineering
• Subjects: degradation processes; dynamic load power; stiffness force powers; impendence modes
• Online Access: https://www.jvejournals.com/article/17717

Changes in the dynamic state of a mechanical structure, as described by energy-related characteristics of the loads of the vibration nodes in a mechanical system, are a significant indicator of differences or changes taking place in its structure. The authors have outlined a method for analysing the fatigue degradation of mechanical structures described in terms of variations in the dynamic mobility, impedances, their real and imaginary parts and fluctuations in the strength of dynamic stiffness and the strength of the internal damping of structures expressed as a function of degradation time (the number of degrading impulse impacts). Information about the technical condition of the individual material samples have been obtained on the basis of the energy characteristics of power spectral density under degrading dynamic load. The dynamic load power distribution matrix defined as the quotient of vector of vibration rate and transposed forcing action vector. The results were presented in the form of power amplitude estimation of the dynamic stiffness forces and damping forces, changing with the ongoing samples degradation process. The variations are identified over the full scope of destruction ranging from nucleation to dominant fracturing. Such an identification is carried out by the method of experimental modal analysis and by energy-based methods with the use of a mechatronic accelerated testing station. The paper provides definitions of the related measurable measures of the process. The point is illustrated with an overview of selected strength characteristics of modern construction steel.