This method comprises: generating, only using the device, a low-frequency signal that makes the structure vibrate, generating a high-frequency signal in the structure, measuring a vibratory signal caused by the generated low-frequency and high-frequency signals at the same time then adaptively re-sampling these measurements to obtain a re-sampled vibratory signal the power spectrum of which comprises: a first frequency range [u.sub.BFmin; u.sub.BFmax] of width larger than 5 Hz that contains 95% of the power of the low-frequency signal, a second frequency range [u.sub.HFmin; u.sub.HFmax] of width systematically smaller than u.sub.BFmin that contains 95% of the power of the low-frequency signal, signaling a defect in the structure if an additional power lobe is detected outside of the ranges [u.sub.BFmin; u.sub.BFmax] and [u.sub.HFmin; u.sub.HFmax].

A system includes several load cells, each coupled to a lashing that secures shipping containers, accelerometer cells, each coupled to a shipping container at the top of a stack, and an inclinometer cell coupled to a cargo ship. The cells are configured to transmit data to a computer. All the cells comprise a processor programmed to acquire a time series of measurements and, preferably, decompose the time series into a sum of sinusoidal signals, each having a frequency and an amplitude. Alternatively, the computer can be programmed to decompose the time series. The computer is programmed to identify the signal components caused by the roll of the cargo ship or by resonances in shipping container stacks. The computer estimates cumulated damages caused by fatigue in the lashings and/or twist locks. The system is used to trigger alarms and/or schedule maintenance.

A one-dimensional (1D) and two-dimensional (2D) scan scheme for a tracking continuously scanning laser Doppler vibrometer (CSLDV) system to scan the whole surface of a rotating structure excited by a random force. A tracking CSLDV system tracks a rotating structure and sweep its laser spot on its surface. The measured response of the structure using the scan scheme of the tracking CSLDV system is considered as the response of the whole surface of the structure subject to random excitation. The measured response can be processed by operational modal analysis (OMA) methods (e.g., an improved lifting method, an improved demodulation method, an improved 2D demodulation method). Damped natural frequencies of the rotating structure are estimated from the fast Fourier transform of the measured response. Undamped full-field mode shapes are estimated by multiplying the measured response using sinusoids whose frequencies are estimated damped natural frequencies.

A diagnosis device includes a data acquirer, a data recorder, and a health diagnoser. The data acquirer acquires a measurement data of a structure at a predetermined timing. The data recorder causes a storage to store the measurement data acquired by the data acquirer as a standard data. The health diagnoser diagnoses a health of the structure by comparing the measurement data that is acquired by the data acquirer this time with the standard data that has been acquired by the data acquirer last time and stored in the storage.

A reusable piezoelectric sensor for damage identification includes a piezoelectric ceramic plate and a metal box bonded to the surface of a test piece, where a wire through hole is formed in the center of a top plate of the metal box, and a side wall of the metal box extends vertically upwards to form a striking face for being struck to remove the metal box from the test piece; the piezoelectric ceramic plate arranged in the metal box is closely and fixedly bonded to a bottom plate of the metal box; and wires of the piezoelectric ceramic plate penetrate through the wire through hole to be connected to an external impedance analyzer. The reusable piezoelectric sensor for damage identification is easy to manufacture and convenient to operate and can effectively eliminate the testing error caused by the difference of the piezoelectric ceramic plate.

The invention relates to a mechanical testing device with at least one load frame , and , which has a frame part and a clamping device held therein, in which a beam-shaped test specimen, in particular a rotor blade or rotor blade segment, can be clamped projecting through the load frame, the load frame being mounted in a first pivot bearing arrangement on a carrier frame or a support frame so as to be rotatable about a first transverse axis of the test specimen which extends perpendicularly to its longitudinal axis projecting through the clamping device, wherein the frame part has a four-fold rotational symmetry, in particular a square shape, or an annular shape. The design of the load frame(s) results in easy rotatability/adjustability of the test specimen. In a method for carrying out the test, the system natural frequencies in different loading directions can be suitably matched.

The disclosure is directed to a method comprising the steps: carrying out multiple measurements on a mechanical object, the measurements each differing by one or more parameters influencing the measurement; determining a spectrogram on the basis of the measurement data of the measurements and depending on a predefined parameter of the mechanical object; determining one or more excitations of the mechanical object; reproducing the excitations in the spectrogram.

A method for identifying prestress force in single-span or multi-span PCI girder-bridges is provided. The method includes non-destructive steps for obtaining a set of parameters of the PCI girder-bridge under investigation, and combines various analyses to identify the change of prestress force. Therefore, the losses of prestress force are tracked and predicted. The method does not cause structural damages along the PCI girder-bridge, and the cost of the identification is significantly decreased.

The disclosure provides a method for identifying a modal frequency of a beam bridge by considering influence of environmental temperature. The method includes the following steps: installing a sensor on a newly-built beam bridge without damage, measuring a dynamic response of the nearn bridge cinder ambient excitation, recording temperature data, processing by a modal parameter identification method to obtain a modal frequency value at the temperature, and titarling from a modal frequency corresponding to the temperature, carrying out iterative calculation to obtain the modal frequency at any temperature. The modal frequency value at any temperature is obtained by arranging a small number of sensors and canying out a small number of tests, so that the influence of the temperature on the modal frequency is quantified, furthermore, the part of environmental influence is eliminated in future damage evaluation of the beam bridge, which allows for a more accurate isamage evaluation rttsult,

The invention discloses an experimental system of surrounding rock and lining structure under unequal surrounding pressure and water pressure, comprising: reaction wall, lining structure, external water pressure loading mechanism, internal water pressure loading mechanism, prestress-loading mechanism, surrounding rock layer and monitoring device. The Experimental System can simulate the stress characteristics and related deformation characteristics of the surrounding rock of the tunnel and the lining structure of the water conveyance tunnel under complex internal and external loads in the actual environment, and can help to analyze and study the broken appearance of the lining structure and the crack distribution after cracking.