1shock and vibration testing

... they cannot give significant vibration generation at once-per-tooth frequency and harmonics This, at first sight, seems peculiar and if, as in Fig 4.5, we plot typical random adjacent pitch errors ... called the pitch line and is where the two pitch cylinders touch The pressure plane is limited at either end as the "unwrapping band" unreels from one base cylinder and reels onto the other ... series of pinion tooth flanks with completely arbitrary flank shapes including corrections and errors and with arbitrary pitch errors These flanks could then be matched with a corresponding set

Ngày tải lên: 05/08/2014, 09:20

... generated in line 33 and is stored for plotting and to be used to calculate accelerations in lines 37 to 40 Accelerations and velocities are multiplied by the time increment and are added to existing ... line, partly due to the gear flank shapes and partly due to the vibration If the nominal mean elastic deflection in the mesh is of the order of 10 urn, then a vibration of 2 ujn can easily alter the ... involved, two linear and two torsional and if the system is linear with a constant contact stiffness Sc the estimation of response is simple A force P at the contact will give linear and torsional responses

Ngày tải lên: 05/08/2014, 09:20

... 9the combined internal and external resonances by measuring the bearing vibrations and the noise simultaneously This gives T.E to bearing vibration as well as bearing vibration to noise Whether ... the vibration power going into the support via that route, again taking note of phase angles As in Fig 6.8, if the velocities of vibration above and below the isolator are V l and V2 (complex) and ... be mounted on vibration isolators in an attempt to limit transmission of vibration away from the gearbox, e.g., in a car the combined engine and gearbox is rubber mounted to reduce vibration into

Ngày tải lên: 05/08/2014, 09:20

... Typically, with a gear ratio of 19:31 and the standard 18,000 (x 4) line encoders and 12 bit digital recording, the resolution would be to about 0.1 second of arc and more than adequate for automobile ... disadvantages are that the shaft must run true or lateral vibrations will be high and the shaft must be strong enough to take the weight and vibration of the encoder body This is not usually true ... work is a blend of the high speed and velocity approaches Each encoder string is processed separately and is simply taken to a demodulator The two resulting vibrations can then either be logged

Ngày tải lên: 05/08/2014, 09:20

... rise very rapidly if we depart from what is standard and easily available so it is advisable to tailor testing to current standard PC performance A standard PC together with a basic 16-channel 12 ... requirements for most gear noise and vibration work are relatively modest Necessary recording frequencies are limited since 1450 rpm and 24 teeth is less than 600 Hz tooth frequency and we can record up ... noise or vibration is due to isolated impulses or to steady excitation Steady vibration, typically at one-per-tooth frequency, is easily recorded by hand since the frequency is obvious and there

Ngày tải lên: 05/08/2014, 09:20

... analysis and add bands in groups If the original record was for 10 s the bandwith would be 0.1 Hz and adding 10 bands would widen the bandwidth to 1 Hz The addition is an addition of power in the bands ... frequency analysis is carried out on a vibration or T.E the band width of the resulting display is controlled by the testing time Testing for 1 sec would give a bandwidth of 1 Hz for the output graph ... phase and gave a negative with cancellation over a long period Testing at all frequencies and with both sin and cosine detects all possible components This classical approach involved testing

Ngày tải lên: 05/08/2014, 09:20

... are used to evaluate shock and vibration environments, to devise testing procedures and testing machines, and to design and operate equipment and machinery Shock and/ or vibration may be either wanted ... frequencies f1 and f2 They involve the periodic increase and decrease of amplitude at the beat frequency (f1 − f2) beats broadband random vibration Broadband random vibration is random vibration having ... degree-of-freedom system narrow-band random vibration (random sine wave) Narrow-band random vibration is random vibration having frequency components only within a narrow band It has the appearance...

Ngày tải lên: 11/08/2014, 07:23

... are used to evaluate shock and vibration environments, to devise testing procedures and testing machines, and to design and operate equipment and machinery Shock and/ or vibration may be either wanted ... frequencies f1 and f2 They involve the periodic increase and decrease of amplitude at the beat frequency (f1 − f2) beats broadband random vibration Broadband random vibration is random vibration having ... degree-of-freedom system narrow-band random vibration (random sine wave) Narrow-band random vibration is random vibration having frequency components only within a narrow band It has the appearance...

Ngày tải lên: 29/06/2014, 09:21

... equations, Eqs (3.31e) and (3.31f ), and two sets each consisting of two coupled equations [Eqs (3.31a) and (3.31d); Eqs (3.31b) and (3.31c)] The planes of symmetry are the XZ and YZ planes For example, ... Z″ are transferred to the mutually paralay; that between Z″ and Z′ is az The lel axes X′, Y′, Z′ by Eqs (3.14) and (3.15), and moments and products of inertia of the then to the inclined axes X, ... oscillations about X and Z are uncoupled The angle θ0 and the moment of inertia about the Z axis give Ixz by Eq (3.28) When the moments and product of inertia with respect to a pair of axes X and Z in a...

Ngày tải lên: 11/08/2014, 07:23

... Mounting Systems,” J of Vibration and Acoustics, 117(B):117–161, 1995 Choi, Y S., and S T Noah: “Forced Periodic Vibration of Unsymmetric Piecewise-Linear Systems,” J of Sound and Vibration, 121(3):117–126, ... NONLINEAR VIBRATION 4.45 Ehrich, F F.: “Observations of Subcritical Superharmonic and Chaotic Response in Rotordynamics,” J of Vibration and Acoustics, 114(1):93–100, 1992 Nayfeh, A H., B Balachandran, ... Rubs and Chatter Instabilities in Forced Vibrations Bistable vibration Unstable imbalance In each instance, the physical mechanism is described and aspects of its prevention or its diagnosis and...

Ngày tải lên: 11/08/2014, 07:23

... frequencies and normal modes of small vibration of a rectangular plate of length a, width b, and thickness h are to be calculated All edges are hinged and subjected to unchanging normal forces Nx and ... executing lateral vibration (B) Element of beam showing shear forces and bending moments 8434_Harris_07_b.qxd 09/20/2001 11:24 AM Page 7.14 7.14 CHAPTER SEVEN and that caused by the vibration. The ... if the amplitude of the vibration is known EXAMPLE 7.4 The natural frequencies and modes of vibration of the rectangular steel beam shown in Fig 7.6 are to be determined and the fundamental frequency...

Ngày tải lên: 11/08/2014, 07:23

... measurements and shock and vibration data should not be taken until stabilization is reached 8434_Harris_12_b.qxd 09/20/2001 11:15 AM Page 12.29 VIBRATION TRANSDUCERS 12.29 Input and Output Resistance ... required to band-limit the signal, possibly to integrate it (to velocity and/ or displacement), and to adjust the gain High- and low-pass filters normally are required to remove extraneous low- and high-frequency ... replace the rectifier VIBRATION METERS Vibration meters are instruments which receive a signal from a vibration transducer and process it so as to give an indication of relevant vibration parameters...

Ngày tải lên: 11/08/2014, 07:23

... of vanes and blades in pumps and fans, number of motor poles, and number of stator slots and rotor bars Vibratory forces such as misalignment, mass unbalance, and reciprocating masses Vibration ... to the frequency and amplitude ranges for which the secondary standard has been calibrated and for which the vibration exciter has adequate rectilinear motion The secondary standard accelerometer ... in the vibration spectrum at the machine speed and in the radial direction However, dynamic unbalance may also result in a rocking motion and consequently in vibration in both radial and axial...

Ngày tải lên: 11/08/2014, 07:23

... of tests and experiments, transmissibility of gloves and resilient materials, and terminology (See Chap 42.) Testing Numerous standards and handbooks that cover shock and vibration testing have ... visco-elastic materials using vibration NASA Standards and Handbooks NASA has issued three standards (STD) and two handbooks (HDBK) related to shock and vibration testing that are approved for ... International Standard (NAIS) ANSI S2.1 Use and Calibration of Transducers and Instrumentation The use and calibration of shock and vibration transducers and instrumentation, including standardized...

Ngày tải lên: 11/08/2014, 07:23

... signal has random amplitude and random phase distribution and contains energy throughout the frequency spectrum The difference between this signal and the periodic random signal is that the random ... Time-history and line spectrum for almost-periodic vibration STATIONARY RANDOM VIBRATIONS By definition, random vibrations cannot be described by an explicit mathematical function and, hence, ... 12:06 PM Page 22.9 CONCEPTS IN VIBRATION DATA ANALYSIS 22.9 (A) (B) FIGURE 22.6 Time-histories and autospectra for wide-bandwidth (A) and narrow-bandwidth (B) random vibrations Wxy(f) = |Wxy(f)|e−jθxy(f)...

Ngày tải lên: 11/08/2014, 07:23