Abstract: A system and method for blade health inspection is provided. The system may include a health monitoring processor, an excitation actuator, and a health monitoring sensor. The excitation actuator may pulse a force against an engine blade to cause non-integral vibratory excitations in engine blades. The health monitoring sensor may measure the vibratory excitations. The health monitoring processor may analyze the vibratory excitations to determine the health of the engine blade.

Abstract: Vibration test arrangements incorporate an isolation device. In order to allow the isolation device to operate on one side only of a component subject to vibration testing a clamp association is provided between isolation elements. An abutment pressure to retain and present the component is generated between the isolation elements utilizing the clamp association and an appropriate displacement mechanism. The displacement mechanism is controlled by a controller in a control loop incorporating a sensor to determine operational characteristics of the arrangement and appropriate drivers for the displacement mechanism.

Abstract: A method of operating a vibratory testing apparatus is disclosed including providing a table frame with at least one vibrator attached thereto and attaching the at least one vibrator to a solenoid valve, wherein an input of the solenoid valve is connected to a pneumatic air supply and an output of the valve is connected to the vibrator. The solenoid valve is connected to a controller and a first control signal is sent from the controller to the solenoid valve for opening the valve and allowing a first burst of air to the vibrator thereby causing the vibrator to vibrate the table frame at a first amplitude. Then a second control signal is sent from the controller to the solenoid valve for opening the valve and allowing a second burst of air to the vibrator thereby causing the vibrator to vibrate the table frame at a second amplitude.

Abstract: A method of measuring vibration in a bladed rotor structure with a vibration monitor. The vibration monitor includes a sensor for sensing passage of the sensor targets on radially outer portions of the blade structure, and the sensor generates signals corresponding to target passing events. An excitation structure is provided including at least one air jet for providing an excitation force to the blade structure. The blade structure is rotated about an axis of rotation and the air jet is driven in a circular path about the axis of rotation at a different rotational speed to apply a non-synchronous excitation force to the blade structure.

Abstract: An apparatus and method for testing vibration in a bladed disk includes a motor-driven rotor upon which the bladed disk can be attached. At least one nozzle coupled with a liquid source is positioned to direct liquid from the liquid source to a position where it would impact at least one blade of the rotating bladed disk. The stress state and/or position of a rotating blade, so impacted, can be monitored to test its vibration characteristics.

Abstract: A method of and apparatus for measuring a tension by the steps of vibrating a measured object of a line- or belt-shaped configuration by the flow of air from an air nozzle so that the measured object is resonated, counting the number of vibrations of the measured object per second by the radiation of a laser light emitted from a very small distance measuring device, and calculating a resonance frequency of the measured object from the number of the vibrations to thereby obtain a tension of the measured object.

Abstract: A flutter exciter induces vibration either for actual aircraft flight testing or for wind tunnel model testing. The basic flutter exciter unit is a pair of rotatable concentric cylinders mounted on either a fixed vane or an aircraft wing or a tail surface. Each cylinder has a slot which allows the air flow to pass therethrough. By rotating the cylinders together, oscillating air pressures are induced on the fixed vane or the aircraft surface to which the cylinders are attached. The cylinders may be mounted at a trailing edge of either the fixed vane or the aircraft wing, to any tail surface, or on any other lifting surfaces of the aircraft itself. Thus, because the flutter exciter can be made as a completely self-contained unit, it may be simply mounted to any suitable hard point on either the test model or the aircraft. The power required to rotate the slotted cylinders is minimal, thus allowing the use of a low wattage motor.

Abstract: System and method for characterizing the resonant responses of a plurality of rotating blades in a turbo machine. The system comprises a plurality of controllable fluid jets disposed about a blade row for exciting rotating blades with selectable frequencies of vibration. The sequential excitation of blades at a plurality of narrowly spaced frequencies and the simultaneous sensing of blade responses sufficiently resolves the resonant center frequencies and harmonics thereof in order to detect changes in characteristic blade resonances.

Abstract: An apparatus for inducing high frequency out-of-phase, vibrations in adjacent span-wise panel portions of a plate type structure, such as an airfoil blade of a gas turbine engine. The apparatus includes a novel bifurcated duct for conducting and directing two out-of-phase streams of gaseous flow, and a uniquely structured air chopper which generates the two out-of-phase gaseous streams. The duct has an upstream end with which the output of the air chopper is in communication, and a stepped-down downstream end at which the airfoil blade (or other plate type structure specimen that is to be tested) is held, supported, and positioned in a chord-wise direction, such that the two out-of-phase gaseous streams impinge upon, and induce the same high frequency vibration in, two preselected, adjacent, span-wise panel portions of the specimen, thereby the panel portions vibrate out-of-phase.

Abstract: A hydraulic drive system for an underwater vibrator has a hydraulically driven mass for generating a seismic wave into the seabed. The hydraulic drive system for the vibrator is accomplished by filtering sea water, conveying the filtered sea water to the hydraulic pump where the sea water under pressure is supplied through a control valve to the hydraulic vibrator. The output from the control valve is coupled to the sea water. The hydraulic system provides hydraulic fluid which will not need to be cooled, thereby eliminating the normal cooling system along with several necessary accumulators and sump which are used in a closed hydraulic system.

Abstract: Apparatus for non-destructively monitoring the bonding quality of an ultrasonic bonding system by detecting the amplitude deviation of a vibrating bonding tool between the vibration amplitude thereof in the freely vibrating (no-load) condition and the vibration amplitude during an ultrasonic bonding operation.

Abstract: A probe carrying a readily replaceable, inflatable bladder for sealingly positioning the probe. A trio of conduits terminate at a disc at an end of the probe to provide audio stimulus, audio detection and air pressure control. Transducers coupled to sound transmitting conduits are carried in a pair of housings mounted on a frame which supports the axially and radially adjustable probe.

Abstract: Apparatus for sensing particles in a fluid medium comprising an ultrasonic resonant cavity for containing a fluid medium. A first transducer on one side of the cavity continuously propagates thereacross ultrasonic compressional waves whose phase and amplitude are perturbed by the presence of particles in the fluid medium. A second transducer positioned on the opposite side of the cavity from the first transducer substantially parallel to and in registry therewith receives the ultrasonic waves and converts them to rf electric waves of the same frequency, the rf electric waves having their phases and amplitudes modulated in response to any perturbations in the ultrasonic waves. The rf waves are amplified and fedback to the first transducer thereby to establish an oscillatory circuit.

Abstract: Apparatus for determination of the freezing point of a liquid or solution has a probe extending into the liquid with means for vibrating the probe. Fixed elements which are cooled, e.g. Peltier plates, are arranged adjacent probe so that a mantle of solid forms on these elements and grows to touch the probe, thereby changing the resonant frequency. This change in resonant frequency is sensed and used to control the cooling so that the probe remains just in contact with a surface where solid is forming, i.e. in liquid at the freezing point. The probe temperature is sensed electrically, e.g. with a resistance thermometer.

Abstract: A force measuring apparatus having a vibrator which resonates with the frequency of a vibration generator. The force to be measured is applied directly to the vibrator in a manner to effectively tune it to the frequency of the generator. The vibrating motions of the vibrator are transmitted to a transducer which converts them to an electric signal which in turn is fed into a readout device.

Abstract: Apparatus and method for measuring the impedance of oscillatory systems, or elements of such systems, which exhibit nonlinear behavior at high excitation amplitudes. Excitation of the element being tested, which element may be either acoustical, electrical, or mechanical, is in the form of a combination of a high-intensity biasing signal having a broadband spectrum, and a low-intensity pure sinusoidal tracer signal. The tracer signal is retrieved at an appropriate measuring point in the test system by means of highly-selective filtering. Although the broadband signal comprises the real or basic test signal input to the test element, the retrieved tracer signal is substituted therefor for the purpose of deriving the element's impedance through the use of conventional impedance algorithms. Algorithm solutions thus provided correspond to the response of the element to the entire spectrum of the broadband excitation.

Abstract: Surface properties, such as, hardness, of a test piece are determined by holding a mechanical resonator, for example, in the form of a sensor rod against a surface of the test piece with a static force sufficient to maintain steady contact with the test piece surface at a contact surface on the sensor rod shaped to provide an increasing area of contact with increasing plastic and/or elastic indentation or deformation of the test piece surface, exciting the test piece into vibration with a frequency which is varied so that the vibrations transmitted from the test piece to the sensor rod will cause the latter to attain a state of resonance, for example, as indicated when a maximum amplitude of the vibration of the sensor rod is sensed, measuring the amplitude of vibration of the excited test piece at a region of the latter which is adjacent to, but outside of the area of contact of the test piece with the contact surface on the sensor rod, for example, by means of an auxiliary sensor, and further varying the fr

Abstract: The invention refers to a measuring circuit for determining the properties of a workpiece, particularly hardness, using the contact impedance method in which a probe resonating at an ultrasonic frequency provided with a workpiece engaging tip is utilized. The measuring circuit uses digital counters for producing a digital count which is the difference between the free-resonant frequency of the test probe and the resonant frequency of the probe when the probe is in forced contact with the workpiece. A read-only-memory (ROM) converts the difference frequency count to a hardness value, such as Vickers or Rockwell. The disclosed arrangement obviates the need for zeroizing the circuit and, hence, is self-compensating in respect to drift and thermal stability.

Abstract: The dynamic parameters of soil in situ are determined by: impacting freely suspended piles and measuring the force applied to and the acceleration of the piles; analyzing the measured information to determine the transfer function (impedance) of the piles; driving the piles into the soil whose dynamic parameters are to be determined; impacting one of the piles driven into the soil; measuring the force applied to and the acceleration of the driven pile; measuring the acceleration produced by the driven pile at at least one remote pile; analyzing the measured information obtained with the piles located in the soil to determine the transfer functions of the soil plus the piles; and, subtracting the transfer functions of the piles from the transfer functions of the piles plus the soil to determine the transfer function of the soil. The transfer function when plotted depicts the dynamic parameters of the soil.

Abstract: The method of measuring dynamic characteristics of materials consists in obtaining, in the course of measurement, a control current which ensures oscillations of a specimen of a material at a preset amplitude and frequency. Then, real and imaginary components of the control current are discriminated, and two restoring currents are generated; these currents are summated, and the total current is used to control the movement of the specimen; after that, the real and imaginary components of the control current are discriminated for the second time, and their value, as well as the values of the restoring currents and the preset amplitude and frequency of the deformation of the specimen are used to calculate dynamic characteristics of the material.

Abstract: The dynamic mechanical properties of polymeric materials can be measured either in uniaxial compression or in flexure as a function of frequency over a wide frequency as well as temperature range, by using a piezoelectric driver to apply a displacement to a sample and a piezoelectric pickup to pick up the forces transmitted through the sample together with electrical circuitry whereby the amplitude ratio and phase angle between drive and pickup signals may be read.