The acoustic emission method has been adopted for detection of damage mechanisms in carbon-fiber-reinforced polymer composite tubes during the three-point bending test. The damage evolution process of the individual samples has been monitored using the acoustic emission method, which is one of the non-destructive methods. The obtained data were then subjected to a two-step technique, which combines the unsupervised pattern recognition approach utilizing the short-time frequency spectra with the boundary curve enabling the already clustered data to be additionally filtered. The boundary curve identification has been carried out on the basis of preliminary tensile tests of the carbon fiber sheafs, where, by overlapping the force versus time dependency by the acoustic emission activity versus time dependency, it was possible to identify the boundary which will separate the signals originating from the fiber break from unwanted secondary sources. The application of the presented two-step method resulted in the identification of the failure mechanisms such as matrix cracking, fiber break, decohesion, and debonding. Besides the comparison of the results with already published research papers, the study presents the comprehensive parametric acoustic emission signal analysis of the individual clusters.

The auto-balancing mechanism is used in the spin-dry regime of the laundry machine. The high rotating speed and unbalanced mass inside the drum create centrifugal force, which is the cause of vibration. The auto-balancing mechanism consists of a set of balls in the circular guiding track. During the spin-dry process, the balls settle in the opposite position to an unbalanced mass. The centrifugal force of the balls compensates the one of the unbalanced masses. The paper deals with the non-linear numerical simulation of the imbalance settlement and the following parametric study. The solution to the problem is demonstrated on an industrial laundry machine with a maximum capacity of 7 kg of dry laundry and a maximum rotating speed of 930 rpm. The proposed numerical model allows us to investigate the behavior of the auto-balancing mechanism and predict the vibration amplitudes of the system.

This article explores the structural identifiability of parameters within non-linear physical models, focussing specifically on the Anand material model. The proposed procedure is structured in two key steps: first, a local analysis identifies the most suitable parameters for testing. Subsequently, these selected parameters, along with their admissible value intervals, are evaluated for global structural dependence. Our innovative numerical approach systematically reduces the parameter count by substituting selected parameters with frozen values (constants). The study employs simulations of the finite element method of a simplified tensile test, utilising the Anand material model. The independent parameters identified through this method are then validated against a tensile test dataset. The validation results indicate a high probability that the use of a reduced parameter set yields unique values for the Anand model parameters in the tensile tests, underscoring the efficacy of our approach.

This paper details the possibility of simulating HELICOIL^® inserts using Finite Element Analysis and contact technology. The main procedure is based on the use of contact elements in the Glue–Cohesive setting, which is usually considered for the simulation of composites. The contact represents the behaviour of an interface, including the HELICOIL^® insert, the sample threads, and the screw threads. The behaviour of the cohesive contact is determined by a multi-linear curve, and is described by several parameters. Our main goal is to determine the number of parameters and their values to provide a defined accuracy. The sample is made of ABS-M30 material, while the screw is made of steel. The Finite Element Model Updating method is used to determine the parameters from experimental data. The problem regarding the addition of a point (parameter) to a multi-linear curve is solved using the principle of halving intervals. A gradient approach combined with a penalisation method is used to identify the parameters of the interface model. The simulation results are compared with data obtained through Digital Image Correlation measurements.