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Damages of different kinds that can be inflicted to a parked car. Among them, loosening of the car wheel bolts is difficult to detect during normal use of the car and is at the same time very dangerous to the health and life of the driver. Moreover, in patents and publications, only little information is presented about electronic sensors available for activation from inside of the car to inform the driver about the mentioned dangerous situation. Thus, the main aim of this work is the proposition and examination of a sensing device using of a wireless accelerometer head to detect loosening of wheel fixing bolts before ride has been started. The proposed sensing device consists of a wireless accelerometer head, an assembly interface and a receiver unit. The assembly interface between the head and the inner part of the rim enables the correct operation of the system. The data processing algorithm developed for the receiver unit enables the proper detection of the unscrewing of bolts. Moreover, the tested algorithm is resistant to the interference signals generated in the accelerometer head by cars and men passing in close distance.

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Supports are one of the most popular structural elements in engineering. They have a wide range of applications, including in pressure gauge connectors, fixtures for photovoltaic and solar panels, and traffic signs. Supports are also used in highly complex engineering projects such as airplane wings or rotor blades. Monitoring methods for detecting and predicting the condition of support structures have become an important area of research. Structural damage to machines and machine parts can be prevented through early detection of fatigue cracks with the use of nondestructive methods. The paper proposes a method for detecting fatigue cracks along the cross-sectional area of a specimen based on selected parameters of the vibration signal. The diagnostic signal for analyses of specimen cross-sectional area was vibration acceleration, which was described with the use of the following parameters: changes in amplitude and waveform (FFT), RMS amplitude, changes in the amplitude of a vibrating sample, and changes in the phase angle of a vibrating sample. In the test stand, cross-sectional damage was caused by forces of inertia acting on the specimen. The results of the study indicate that all of the analysed parameters can be used to detect the loss of structural continuity (mechanical and fatigue cracks) in an object. An analysis of changes in the amplitude of a vibrating sample was the fastest and most comprehensive source of information.

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