Abstract: The invention proposes sensor elements (5) for detecting a physical measurement variable such as a pressure, a temperature, a gap width, or a capacitance between two bodies (10, 20) that move in relation to each other during operation and experience high tribological stress. In certain areas between the surfaces of the bodies (10, 20) that move in relation to each other, in a surface region of at least one of the bodies (10), a sensitive layer (13, 30), in particular a sensor segment (13), is provided, which is separated from the body (10) by an insulation layer (12) and has a covering layer (14) in a first embodiment. In an alternative embodiment, a surface region of at least one of the two bodies (10) has a recess (23) in which the sensor surface (13) is disposed on the insulation layer (12). In a third embodiment, the sensor surface (13) has a length of 10 ?m to 5 mm, a width of less than 5 ?m, and a thickness of less than 200 nm.

Abstract: A fixing member is composed of an upper washer and a lower washer; and a sensor substrate is sandwiched and held by the upper and lower washers. A strain-detecting element is disposed on the sensor substrate. A strain sensor as configured above is fixed onto a measurement target via the fixing member. Accordingly, the strain sensor does not generate an output signal when no external force is applied, demonstrating stable characteristics.

Abstract: A method for reducing force and position control tracking errors caused by changes in hydraulic pressure at the actuator ports of a hydraulic servo valve. The method may use either the force command signal or the load cell signal in conjunction with a mathematical algorithm to compensate for changes in the flow capacity in the servo valve caused by changes in pressure at its ports. Good performance can be attained using the load cell signal. Alternatively, the algorithm can use the force command signal. The performance of the control loop with proper velocity feed-forward compensation keeps the feedback signal largely in phase with the command. Pressure sensors for detecting pressure changes at the actuator ports of the servo valve are not required for load droop compensation.

Abstract: A sensor assembly includes a elongate article and a plurality of elongate piezoelectric elements provided to the elongate article. Each of the piezoelectric elements is configured so that when a load is applied in a direction perpendicular to a surface of the piezoelectric element, a short axis direction of the piezoelectric element becomes a sensitivity direction in which a voltage is generated, and a major axis direction becomes a non-sensitivity direction in which a voltage is not generated.

Abstract: A mechanical-quantity measuring device capable of measuring a strain component of structure deformation for an object to be measured in a particular desired direction with long life, high reliability and high precision. A strain sensor is formed on a semiconductor substrate. Impurity-diffused layers considering the crystal orientation of the semiconductor single crystalline substrate are used to form a Wheatstone bridge circuit on the substrate. The Wheatstone bridge circuit can operate on one substrate since the semiconductor single crystal has the anisotropy of piezoresistance effect.

Abstract: There is disclosed a knitted transducer device comprising a knitted structure having at least one transduction zone, in which the transduction zone is knitted with electrically conductive fibres so that deformation of the knitted structure results in a variation of an electrical property of the transduction zone.

Abstract: The present invention relates to a strain gauge and methods of making such wherein the gauge contains a doped polymeric fluid suitable for measuring elongations of more than 10%.

Abstract: A method and system are provided for obtaining force-displacement responses for a specimen or sample of material. The sample is supported with a spanning portion spanning in an environment between at least three points not in a line, wherein the points are fixed relative to each other, and wherein the spanning portion is capable of displacement relative to the points. An oscillating mechanical excitation at at least one frequency and at at least one known amplitude is applied to the spanning portion. In addition, at least one other mechanical excitation is also applied to the spanning portion independently of the oscillating mechanical excitation.

Abstract: A capacitive pressure sensor includes a substrate assembly having a conductive layer. A conductive membrane is mounted to the substrate assembly so that a sealed reference chamber is defined by the conductive membrane and the substrate assembly. A cap is arranged on the substrate assembly and defines one or more apertures so that an antechamber is defined between the cap and the conductive membrane. Differential pressure between the reference chamber and antechamber can cause deflection of the conductive membrane which, in turn, varies the capacitance between the conductive membrane and the conductive layer.

Abstract: A fixing member is composed of an upper washer and a lower washer; and a sensor substrate is sandwiched and held with these upper and lower washers. A strain-detecting element is disposed on the sensor substrate. A strain sensor as configured above is fixed onto a measurement target via the fixing member. Accordingly, the strain sensor does not generate an output signal when no external force is applied, demonstrating stable characteristics.

Abstract: There is provided an activity recognition apparatus for detecting an activity of a subject. The apparatus includes: a sensor unit including a plurality of linear motion sensors configured to detect linear motions and a plurality of rotational motion sensors, the linear motions being orthogonal to each other, the rotational motions being orthogonal to each other; and a computational unit configured to receive and process signals from the sensors included in the sensor unit so as to detect an activity of the subject. The sensor unit is directly or indirectly supported by the subject with an arbitrary orientation with respect to the subject. The computational unit performs a calculation that uses the signals from both linear motion sensors and rotational motion sensors to determine the activity of the subject independent of the orientation of the sensor unit.

Abstract: A controlled system (480) for application of force on a test object includes a force actuator (484) that is coupled to and applies a force on the test object. A velocity signal generator (482) is in a feedforward configuration relative to the force actuator (484) and generates a velocity signal (503) that is predictive of the velocity of the test object. A controller (482) is coupled to the force actuator (484) and to the velocity signal generator (482) and generates a desired applied force signal (546) compensated by the velocity signal (503).

Abstract: A load cell apparatus and method for forming the same. A load cell apparatus is configured to include a load cell housing and a modular strain gage element that is modularly assembled into the load cell housing. The load cell housing and the modular strain gage element together form a load cell apparatus for use in electronic force sensor applications. The modular strain gage element can be configured from an Advanced Thick Film (ATF) compatible material and can be formed to include one or more contact ledges that allows for a low hysteresis and a proper boundary condition for loading either a tension state or a compression state.

Abstract: In a circuit, as the bridge resistance of one side of a Wheatstone bridge circuit, a distortion gauge (fixed reference resistance) of which variation caused by environmental conditions is suppressed and a sample having a resistance component ?R varied by the environmental conditions are connected in series. A constant bridge input voltage Ei is applied from a constant-voltage power supply to the Wheatstone bridge circuit, a bridge output voltage Eo corresponding to resistance variation of the sample is input to a dynamic distortion amplifier, and a carrier wave signal of a predetermined frequency is output. A measured resistance computing unit samples peak levels of the carrier wave signal output from the dynamic distortion amplifier so as to detect the bridge output voltage Eo, and calculates the resistance of the sample based on the detected bridge output voltage.

Abstract: A system that uses capsules or micro-capsules containing a dye or indicator embedded in a polymer matrix to indicate or measure the degradation of structural materials. The capsules can contain an agent that will be transparent or not detected when the capsule is intact. When the capsule is ruptured, the agent will be either visible to the human eye or measurable by other detection methods. The indicator can either activate upon release or be already activated but not readily visible or detectable in the capsule. An activator compound also can be distributed in the bulk material matrix that activates the indicator upon release. For totally opaque materials like concrete or metal, a surface coating or applied tape containing the capsules can be used.

Abstract: A rivet setting tool is provided to provide improved monitoring of riveted connections during rivet setting. The rivet setting tool includes a head piece for holding a rivet, a device for gripping a rivet pin, a pulling apparatus connected to the device for gripping a rivet pin, and a device for measuring the tension of the pulling apparatus. Using the setting implement according to the invention, a cause of a fault can be determined by means of a comparison between measured values and stored values.

Abstract: A method, system and computer product for detecting the location of a deformation of a structure includes baselining a defined energy transmitting characteristic for each of the plurality of laterally adjacent conductors attached to the structure. Each of the plurality of conductors includes a plurality of segments coupled in series and having an associated unit value representative of the defined energy transmitting characteristic. The plurality of laterally adjacent conductors includes a plurality of identity groups with each identity group including at least one of the plurality of segments from each of the plurality of conductors. Each of the plurality of conductors are monitored for a difference in the defined energy transmitting characteristic when compared with a baseline energy transmitting characteristic for each of the plurality of conductors. When the difference exceeds a threshold value, a location of the deformation along the structure is calculated.

Abstract: A force transducer for measuring axial forces which act essentially transversely on an axis, in particular a measuring axis, has a longitudinally extending axial body, which has a first portion, forming a force introduction zone, at least one second portion, forming a bearing zone, and at least one third portion, forming a force measuring zone for measuring the axial forces. The axial body has in the region of the at least one second portion, radially at a distance from the outside of the same, at least one recess extending in the circumferential direction and directed essentially axially, so that an edge of the second portion that is facing the first portion forms a free overhang.

Abstract: A microelectromechanical systems stress sensor comprising a microelectromechanical systems silicon body. A recess is formed in the silicon body. A silicon element extends into the recess. The silicon element has limited freedom of movement within the recess. An electrical circuit in the silicon element includes a piezoresistor material that allows for sensing changes in resistance that is proportional to bending of the silicon element.

Abstract: A conveyor diagnostic system for monitoring loading of a conveyor line assembly including at least one sensor component coupled to the conveyor line assembly. The sensor component is adapted for detecting loading of the conveyor line assembly and is further adapted for generating and transmitting a signal that is correlative of the loading of the conveyor line assembly. The conveyor diagnostic system also includes a ground station adapted to receive and process the signal that is correlative of the loading of the conveyor line assembly. Furthermore, the conveyor diagnostic system includes a local positioning system that is adapted for detecting the location of the sensor component in relation to a reference point. A method of using the conveyor diagnostic system is also disclosed.

Abstract: A load sensing device comprise an inner member provided at a front part of a vehicle and a load sensor provided at a position before a front of the inner member, in addition to an outer member and a load transfer member. The outer member is provided at the front part of the vehicle so as to be located more frontward than the load sensor so that a space is formed between the outer member and the load sensor. The outer member is in charge of allowing the load sensor to sense, via the outer member, a load applied to a front of the vehicle. The load transfer member, made of a hard material, is disposed adjacently to the load sensor within the space between the outer member and the load sensor. The load sensor is allowed to move along the inner member in the back-and-forth direction of the vehicle.

Abstract: A bolt with a function of measuring strain, comprising a Wheatstone bridge circuit comprising a strain sensor and a dummy resistor, a translate circuit that amplifies a signal from the Wheatstone bridge circuit to convert the same into a digital signal, a transmitting circuit that transmits the digital signal outside the bolt, and a power circuit, by which electromagnetic wave energy received from outside the bolt is supplied as a power source for at least any one of the circuits.

Abstract: A force control system (50, 300) for actuation of a test object (54, 304) includes a force actuator (52, 356) that is coupled to and applies a force on the test object (54, 304). A velocity signal generator (124, 310) is in a feedback configuration relative to the force actuator and generates a velocity signal (150, 324) that is indicative of the velocity of the test object (54, 304). A controller (62, 302) is coupled to the force actuator (52, 356) and to the velocity signal generator (124, 310) and generates a desired applied force signal (130, 380) compensated by the velocity signal (150, 324).

Abstract: A sensor has a plurality of carbon nanotube (CNT)-based conductors operatively positioned on a substrate. The conductors are arranged side-by-side, such as in a substantially parallel relationship to one another. At least one pair of spaced-apart electrodes is coupled to opposing ends of the conductors. A portion of each of the conductors spanning between each pair of electrodes comprises a plurality of carbon nanotubes arranged end-to-end and substantially aligned along an axis. Because a direct correlation exists between the resistance of a carbon nanotube and its strain, changes experienced by the portion of the structure to which the sensor is coupled induce a corresponding change in the electrical properties of the conductors, thereby enabling detection of crack growth in the structure.

Abstract: A fluid pressure sensor (1) for measuring the pressure of a fluid comprises a diaphragm portion (12) which is a strain generating body, a silicon oxide film (21) as an insulating film, and a strain gauge (20) made of crystalline silicon, and austenitic precipitation hardening type Fe—Ni heat-resisting steel excellent in mechanical strength and corrosion resistance is used for the diaphragm portion (12). The silicon oxide film (21) is formed with the internal stress thereof adjusted to the range from ?150 to 130 MPa. With this feature, the fluid pressure sensor (1) ensures high precision and reliability, and may be used even for measurement of a highly corrosive fluid.

Abstract: In a circuit, as the bridge resistance of one side of a Wheatstone bridge circuit, a distortion gauge (fixed reference resistance) of which variation caused by environmental conditions is suppressed and a sample having a resistance component ?R varied by the environmental conditions are connected in series. A constant bridge input voltage Ei is applied from a constant-voltage power supply to the Wheatstone bridge circuit, a bridge output voltage Eo corresponding to resistance variation of the sample is input to a dynamic distortion amplifier, and a carrier wave signal of a predetermined frequency is output. A measured resistance computing unit samples peak levels of the carrier wave signal output from the dynamic distortion amplifier so as to detect the bridge output voltage Eo, and calculates the resistance of the sample based on the detected bridge output voltage.

Abstract: A force sensing membrane comprises (a) a first conductor that is movable toward a second conductor; (b) a second conductor; and (c) a composite material disposed between the first and second conductors for electrically connecting the first and second conductors under application of sufficient pressure therebetween; and (d) means for measuring dynamic electrical response across the force sensing membrane, the composite material comprising conductive particles at least partially embedded in an elastomeric layer, the conductive particles having no relative orientation and being disposed so that substantially all electrical connections made between the first and second conductors are in the z direction, and the elastomeric layer being capable of returning to substantially its original dimensions on release of pressure.

Abstract: Provided are an apparatus for and method and medium of adaptively setting a reference sensing boundary of a touch sensor. The apparatus for adaptively setting a reference sensing boundary includes a reference sensing boundary setting unit adaptively setting a reference sensing boundary of a capacitance using a signal generated by a reference touch sensor; a determination unit determining whether or not a value measured by a device control touch sensor controlling a device to which the reference touch sensor is attached is within the set reference sensing boundary, by sensing a change in the capacitance; and an output unit outputting the measured value if the determination result indicates that the measured value is within the reference sensing boundary.

Abstract: A sensor has a plurality of carbon nanotube (CNT)-based conductors operatively positioned on a substrate. The conductors are arranged side-by-side, such as in a substantially parallel relationship to one another. At least one pair of spaced-apart electrodes is coupled to opposing ends of the conductors. A portion of each of the conductors spanning between each pair of electrodes comprises a plurality of carbon nanotubes arranged end-to-end and substantially aligned along an axis. Because a direct correlation exists between resistance of a carbon nanotube and carbon nanotube strain, changes experienced by the portion of the structure to which the sensor is coupled induce a change in electrical properties of the conductors.

Abstract: Instrumentation for monitoring crack growth using a change in electric potential across a starter crack as the crack propagates is disclosed. The instrumentation includes a specimen of a material to be analyzed for crack growth propagation having a surface with a starter crack formed therein, a plurality of current leads to pass electric current through the specimen, a layer of insulating material disposed on each of opposite sides of the crack, a layer of conductive material disposed on each layer of insulating material, where a portion of each layer of conductive material is in electrical contact with the first specimen surface, and a pair of sensing leads, one sensing lead attached to each layer of conductive material. A method for using the instrumentation to monitor crack growth by measuring is also disclosed.

Abstract: A sensor element (5) detects a physical measurement variable such as a pressure, a temperature, a capacitance, or a gap width between two bodies (10, 20) that move in relation to each other during operation and experience high tribological stress. In certain areas between the surfaces of the bodies (10, 20) that move in relation to each other, in a surface region of at least one of the bodies (10), a sensitive layer (13, 30), in particular a sensor segment (13), is provided, which is separated from the body (10) by an insulation layer (12).

Abstract: A magnetostrictive strain sensor (10) includes a magnetostrictive core (12) comprising a magnetostrictive material, such as a nickel-iron alloy, able to conduct a magnetic flux and whose permeability is alterable by application of a strain. A conductive coil (14) is proximate the magnetostrictive core (12) to generate the magnetic flux when electrically excited. A shell (16) surrounds the conductive coil (14) and the magnetostrictive core (12) for providing a conductive return path for the magnetic flux. An excitation source (18) is electrically connected to the conductive coil (14) for electrically exciting the conductive coil (14) with an alternating current having a constant magnitude. An in-phase voltage circuit (22) is electrically connected across the conductive coil (14). The in-phase voltage circuit (22) senses an in-phase voltage that is in-phase with the alternating current. The in-phase voltage varies correspondingly to the strain subjected to the magnetostrictive core (12).

Abstract: An assembly for use in suspending loads from a load cell comprising: an upper part adapted to be secured to an anchor point and from which a load cell may be suspended; and a lower part adapted to be suspended from the load cell and from which a load may be suspended, in which, in use, the assembly may be used in at least two positions, including: an inoperative position in which the load cell is not fitted, where the lower part and hence the load is supported on the upper part, and an operative position in which the lower part and the load are supported only through the load cell and the lower part does not rest on the upper part.

Abstract: A composite material has a laminated structure of fiber-reinforced resin layers and films of a shape-memory alloy. A predetermined strain has been applied to each film. A damage sensor has a film of an alloy of nickel and titanium. An electric circuit is bonded to the film, and strain gages are connected to the electric circuit. The damage sensor can be laminated to the resin layers in place of the film of the shape-memory alloy. Damage to the composite material is suppressed as follows: A current is applied to the films of the shape-memory alloy, to monitor change in electric resistance of the films. The damage is located in response to the change in electric resistance. Another current is applied to a film of the shape-memory alloy for which the change is larger than the other films to generate heat for deforming the film to generate shrinking stress or shear stress to the damage.

Abstract: There is provided a blind fastener setting tool (12) which has a front end face (218) against which a blind fastener (14) is held during a conventional setting operation and which further has a piezo-electric thin film load measuring device (222) mounted on this front face so as to be disposed and compressed between the front face (218) and a flange (122) of the fastener (14) during the setting operation so as to record a low voltage electrical signal indicative of the load being exerted thereon. There is further provided a method of measuring such load during the setting of a blind fastener by positioning a piezo-electric thin film load measuring device between a setting tool and a fastener and subsequently measuring a low voltage signal created as a result of deformation of the piezo-electric thin film during the setting operation and analysing this signal as indicative of the load exerted on the fastener.

Abstract: A device for sensing an obstacle in said opening range of an automotive closure element movable between an open position and and closed position, more particularly an electrically powered door window (20) or sunroof is provided with a weatherseal (30) sealing the window pane (20). The weatherseal (30) is made of an elastomeric material and secured to a frame (12) of the motor vehicle (10). The device comprises in addition a sensor for sensing an obstacle in the opening range of the closure element (20), the sensor comprising at least one electrical conductor (40) generating an electrical field (F) in the opening range of the closure element (20). The device achieves by simple ways and means an engineered orientation of the electrical field such that any interference by the closure element (20) to the capacitive change in the electrical field (F) is precluded by reason of conductive means (50) comprising a conductive surface (51) made of an electrically conductive material.

Abstract: A sensor device having a magnetostrictive force sensor is provided. To detect a force, the sensor device contains a TMR force sensor element having a magnetic detection layer of material having a magnetostriction coefficient ??|5·10?6|, a magnetically harder reference layer, and a tunnel barrier disposed between these layers. Established in the detection layer is a starting magnetization that relative to the magnetization of the reference layer, which is directed in the direction of force, forms an angle of other than 0° and thus is rotated out of its starting position under the effect of the force.

Abstract: A strain sensor includes a sensor section having a magnetic material provided on one surface of a conductor, the magnetic material being formed integrally with the conductor and having a magnetic strain constant with an absolute value larger than 1×10?7, a fixing mechanism which fixes at least a part of the sensor section, an inductor disposed in a surface side of the sensor section which is opposite the surface on which the magnetic material is provided, the inductor being disposed opposite and away from the sensor section, and a detection unit which detects the amount of deformation of the sensor section caused by stress applied thereto on the basis of a change in inductance of the inductor.

Abstract: An apparatus for measuring pressure includes a cylindrical tube having an open end and a closed end; a piston disposed in the cylindrical tube at the open end; an accelerometer attached to a side of the piston that faces the closed end of the tube, the accelerometer for measuring the acceleration of the piston after a blast event; and a pressure sensor located inside the tube for measuring pressure in the tube between the piston and the closed end of the tube. The apparatus also includes a data processor and computer connected by wires to the accelerometer and pressure sensor for receiving signals generated by the accelerometer and pressure sensor.

Abstract: The present invention is related to a composite sheet material, a method of producing this material, and the application of this material as a sensor for monitoring and measuring shear forces (or lateral translation). In one embodiment, the present invention includes a composite sheet material having an upper and a lower surface comprising an elastomeric matrix, which is essentially non-conductive, and discrete electrically conductive elements within the matrix wherein the electrically conductive elements in a region of the composite sheet material are arranged into columns, and the orientation of these columns are in an essentially organized, non-random pattern with a majority of these columns oriented at angles less than about 90° and greater than about 15° to the lower surface of the composite sheet material. In another embodiment, the present invention provides for a method of forming the sensors.

Abstract: A lateral force-measuring device for a wheel is directed to a rotator axially installed with universal function for moving in an axial direction and is dependently rotated by a rotation of a pressed wheel, and a load-measuring device measuring a moving load for an axial direction of a rotator when a rotator is rotated. A vehicle inspecting system incorporating a lateral-measuring device for a wheel thereon is provided.

Abstract: The present invention discloses a method for evaluating the sound speed end dynamic modulus of elasticity of wood by non-destructive stress wave testing, wherein a timber specimen of long post is placed steadily on a sensor near the center with friction, acting on the interfaces of the sensor and the timber specimen, which resists the timber specimen from moving. Pounding one end of the timber specimen with a striking instrument sends a compression pulse stress wave down the post toward the other end, thereby generating a tension pulse wave back along the post till friction exponentially dissipates the energy of the stress waves. The changing signals of friction received by a receiver support the analyzer to measure longitudinal fundamental frequency of timber specimen; therefore, sound speed and dynamic modulus of elasticity are then calculated.

Abstract: An anti-entrapment system for preventing an object from being entrapped by a translating device includes a capacitance sensor positioned adjacent to the translating device. The sensor has first and second flexible conductors separated by a separation distance. The conductors have a capacitance dependent on the separation distance. The sensor has a compressible dielectric element interposed between the conductors. The capacitance of the conductors changes in response to the separation distance changing as a result of the dielectric element compressing in response to a first object touching the sensor. The capacitance of the conductors changes in response to a second conductive object coming into proximity with at least one conductors. A controller controls the translating device as a function of the capacitance of the conductors to prevent the translating device from entrapping either of the first object or the second conductive object.

Abstract: An inertial sensor with failure threshold includes a first body and a second body, which can move relative to one another and are constrained by a plurality of elastic elements, and a sample element connected between the first body and the second body and shaped so as to be subjected to a stress when the second body is outside of a relative resting position with respect to the first body. The sample element has at least one weakened region. The sensor may also include additional sample elements connected between the first and second bodies.

Abstract: Disclosed is a method for the nondestructive metal characterization and the measurement of stress in the interior of a ferromagnetic part under test by means of measuring a high-frequency electric signal caused by flowing an excitation current through the part under test and/or by the mechanical deformation of the part under test. The present invention is distinguished by the electric potential of the part under test being detected by means of direct or indirect electric tapping on said part under test or a region of said part under test and a high-frequency potential component, which is used as the high-frequency noise signal for determining test parameters, is determined from the electric potential of the part under test caused by changes in magnetization processes.

Abstract: For the metal substrate of a strain sensor, a Mo-containing two-phase stainless steel SUS329 is used. When an insulating layer, electrodes and a resistor are formed on the metal substrate by baking their materials, the alpha phase in the stainless steel of the metal substrate changes to a sigma phase through the baking heat, and, as a result, the range of strain applicable to the sensor within the elastic region of the substrate is broadened and the residual strain of the substrate is reduced. The strain sensor has a broad strain-detectable range and is readily restored to its starting point.

Abstract: The invention concerns a pressure sensor (1), able to operate at high temperature and measure the pressure of a hostile medium, comprising:

Abstract: A strain sensor comprising a metal substrate, a first electrode provided on the metal substrate, a glass layer formed on the first electrode, and a second electrode and a strain detecting resistor provided on the glass layer. In the strain sensor, the insulation resistance between the metal substrate and the second electrode has been raised, and the reliability is high. It can be implemented at low cost.

Abstract: An object of this invention is to provide a dynamic quantity sensor device capable of measuring a dynamic quantity at a high precision and securing insulation of a pressure sensing body easily. This dynamic quantity sensor comprises a pressure sensing body 11 composed of composite ceramics in which material having pressure resistance effect is dispersed on a matrix made of electrical insulation ceramic material and a pressure receiving body 12 having electrical insulation characteristic and disposed on a pressure receiving surface of the pressure receiving body 11, wherein the pressure sensing body and the pressure receiving body are integrated with each other.

Abstract: A non-destructive stress wave testing method for wood. Two strain gauges are disposed on a timber. The timber is struck to generate an impact compression stress wave. The impact compression stress wave is measured by the strain gauges. An oscilloscope is provided to measure the time difference of the impact compression stress wave passing through the semiconductor strain gauges. The resonance frequency of the timber is sensed by the strain gauges and displayed on an FFT spectrum analyzer. Then, the speed of sound in the timber is determined according to the distance between the strain gauges and the time difference, or according to the length and the resonance frequency thereof. The strain gauges may be semiconductor strain gauges. The modulus of elasticity of the timber is determined according to the speed of sound therein and the density thereof.