Semi-active damping of vibrations - PA-R system
The semi-active system for vibration suppression, the so called PA–R System (Prestress Accumulation – Release) is a combination of the vibration damping strategy and the implementation of this strategy in the form of an adaptive clutch. Taking advantage of the Prestress Accumulation–Release (PA–R) strategy, over 95 % of the vibration amplitude can be attenuated in only few cycles of oscillation, by appropriate switching of PAR Nodes to compliant mode of operation. The adaptive clutches of appropriate size can be installed in frame-truss structures to modify the response. A vibration sensor and a dedicated controller adjust stiffness of adaptive clutches in order to achieve superb vibration suppression without providing external mechanical energy into the structure. Only the electrical power for the system is necessary. The efficiency of the PA–R system was presented in an example of the demonstrator structure in the form of a cantilever frame with a length of about 1.20 m.
Main advantages of the PA–R System:
- superb vibration suppression ability,
- no need for significant external energy input (as opposed to active systems, e.g. hydraulic ones),
- fail-safe solution,
- no need to modify boundary conditions of the structure.
Possible applications:
- suppression of vibrations due to impact or other initial conditions,
- stabilization of equipment,
- isolation of a substructure from transient vibrations.
The adaptive clutch is a mechanical interface between structural members, capable of adjusting the bending moment capability of such an interface. Thanks to the innovative technology and unique design (patented), the adaptive clutch maintains its maximum stiffness in the idle mode of its passive operation. Then it switches to the compliant mode within few milliseconds, completely changing the way loads are transferred through the interface, which means ca. 50 times lower load levels than in the idle mode. The adaptive clutch can bear quite significant moments (ca. 50 Nm) relatively to its compact external dimensions (ca. 10 cm). The dimensions of the adaptive clutch can be both downsized or upsized depending on the application.
Main parameters of an adaptive clutch, elaborated for demonstration, are the following:
- height 78 mm,
- outer diameter 88 mm,
- weight 1,8 kg,
- max. moment 50 Nm,
- min. moment 1 Nm,
- actuation voltage 0-150 V.
Main advantages of the adaptive clutch:
- high transferred moment compared to compact design,
- fast reaction time,
- fail safe operation.
Possible applications:
- efficient semi-active vibration attenuation along with PA–R System,
- controllable voltage-driven clutch,
- structural joint of variable bending moment capability,
- structural fuse.
Portable weigh-in-motion rail device
Portable weigh-in-motion rail device is prepared for identification of parameters of loads exerted on the railway track by moving vehicles. The system developed by Adaptronica allows for weighing trains in motion.
Portable weigh-in-motion rail device makes use of the measurement of rail strain caused by the passing train. The device uses portable transducers (patented), attached to the rail foot in a non-destructive manner. The main components of the measurement system are schematically presented in Fig. 1.
The characteristic feature is that the additional preparation of the ballast and sleeper before the system installation is not required. The installation process of the detectors is fast. Closing the railway line is not necessary.
An important advantage of the system is the use of portable detector mounted on the rail foot by clamping elements, which significantly reduces the installation time and cost. The clamping element is designed in such a way that it can be adjusted to all types of rails. Before installation, additional preparation of the track is not required e.g. hardening of the ballast. A view of the portable weigh-in-motion rail device is presented in Fig. 2.
The basic measurement and diagnostic information related to the weighed rail vehicle are included in the time and amplitude parameters of the recorded measurement signal.
Measured parameters
- axle load measurement,
- rail car weight measurement,
- velocity of the rail vehicle measurements,
- number of cars detection,
- axle overload detection,
- unbalanced axle load detection,
- determination of rail vehicle type,
- wheel defects detection.
Basic technical parameters
| velocity range of the rail vehicle: | 5 – 100 [km/h], |
| axle load range: | 1000 – 30000 [kg], |
| velocity measurements precision: | ±3[%] for σ=95[%], |
| axle load measurements precision: | ±5[%] for σ=95[%], |
| rail car weight measurements precision: | ±5[%] for σ=95[%], |
| temperature range of device operation: | -20ºC……..+70ºC. |
Recorder of touch-down parameters - AVI
System AVI of measurement and recording of the touch-down process, elaborated by Adaptronica performs the measurement of vertical speed of an aircraft and its distance from runway during touch-down. The system enables the user to assess the loads acting on the aircraft structure during landing.
The measurement of vertical speed of the aircraft and its distance from runway utilizes a transmitting-receiving ultrasonic head as well as targeted aquisition and signal analysis. The transmitting-receiving head allows for improving the ratio of the analyzed signal to noise level generated by the aircraft in flight.
The level of loads acting on the aicraft structure during touch-down is measured by an accelerometer placed in a preselected spot on the aircraft.
Thanks to aquisition and storage of measurement data on SD card, the system AVI provides better assessment of pilot skills based on recording of the touch-down process. It also enables monitoring of structural fatigue.
AVI can be applied on ultralight and light aircrafts and can be also adapted for unmanned aicraft vehicles.
The advantages of the AVI system are the following:
- possibility of assessment of pilot skills based on recording of the touch-down process,
- better evaluation of structural fatigue due to repetitive loads,
- possibility of assessment of aircraft failures,
- storage of data on SD card,
- waterproof ultrasonic head,
- autonomous power supply,
- low power demand,
- compact dimensions and low mass,
- easy mounting.
Vibration recorder
The main application of the vibration recorder is to take and store measurements of vibrations occurring in heavy-duty constructions and installations during their exploitation. The device elaborated by Adaptronica sp. z o.o. allows for taking measurements in harsh ambient conditions. The vibration recorder is equipped with a 3-axial accelerometer merged with an accompanying cable, which facilitates the installation. The acquired data with proper time signature are stored on SD card of maximum capacity 32 GB. The recorder can be powered through dedicated power supply or through batteries.
Technical data:
- 3-axial measurement of accelerations in the range 2, 4 or 8 g,
- Measurement range from 1 Hz to 300 Hz,
- Data storage on SD card,
- Possibility of setting a low-pass or high-pass filter,
- Possibility of plugging in 2, 3 or 4 sensors,
- Temperature range from -20˚C to 85˚C,
- Durable aluminum housing,
- Possibility of power supply through batteries.
It is possible to expand or adapt the recorder according to customer requirements.
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