Showing papers on "Beam (structure) published in 1985"
TL;DR: In this article, an active vibration damper for a cantilever beam was designed using a distributed-parameter actuator and distributedparameter control theory, and preliminary testing of the damper was performed on the first mode of the beam.
Abstract: An active vibration damper for a cantilever beam was designed using a distributed-parameter actuator and distributed-parameter control theory. The distributed-parameter actuator was a piezoelectric polymer, poly (vinylidene fluoride). Lyapunov's second method for distributed-parameter systems was used to design a control algorithm for the damper. If the angular velocity of the tip of the beam is known, all modes of the beam can be controlled simultaneously. Preliminary testing of the damper was performed on the first mode of the cantilever beam. A linear constant-gain controller and a nonlinear constant-amplitude controller were compared. The baseline loss factor of the first mode was 0.003 for large-amplitude vibrations (± 2 cm tip displacement) decreasing to 0.001 for small vibrations (±0.5 mm tip displacement). The constant-gain controller provided more than a factor of two increase in the modal damping with a feedback voltage limit of 200 V rms. With the same voltage limit, the constant-amplitude controller achieved the same damping as the constant-gain controller for large vibrations, but increased the modal loss factor by more than an order of magnitude to at least 0.040 for small vibration levels.
1,408 citations
996 citations
TL;DR: A proposed standard set of test problems is described and applied to representative quadrilateral plate and solid brick finite elements, some of which have become de facto standards for comparing the accuracy of finite elements.
988 citations
TL;DR: In this article, the authors used fractional calculus to model the viscoelastic behavior of a damping layer in a simply supported beam and analyzed the beam by using both a continuum formulation and a finite element formulation to predict the transient response to a step loading.
Abstract: Fractional calculus is used to model the viscoelastic behavior of a damping layer in a simply supported beam. The beam is analyzed by using both a continuum formulation and a finite element formulation to predict the transient response to a step loading. The construction of the finite element equations of motion and the resulting nontraditional orthogonality conditions for the damped mode shapes are presented. Also presented are the modified forms of matrix iteration required to calculate eigenvalues and mode shapes for the damped structure. The continuum formulation, also incorporating the fractional calculus model, is used to verify the finite element approach. The location of the poles (damping and frequency) are found to be in satisfactory agreement, as are the modal amplitudes for the first several modes.
592 citations
TL;DR: In this article, a set of beam characteristic orthogonal polynomials in the Rayleigh-Ritz method was used to obtain the natural frequencies of rectangular plates. But the results for lower modes were not as good as those obtained by other methods.
456 citations
TL;DR: In this article, the authors obtained equations to predict direct beam and diffuse irradiance in both the visible (PAR) and near-infrared wave bands from measurements of only the total incoming solar radiation.
290 citations
01 Feb 1985
TL;DR: In this article, a polynomial representation of the antenna pattern produced by an equispaced linear array is introduced, where certain roots are displaced from the unit circle radially, to fill a portion of the pattern, which before this displayed lobes interspersed by deep nulls.
Abstract: A technique is introduced which uses the conventional polynomial representation of the antenna pattern produced by an equispaced linear array. Certain roots are displaced from the unit circle radially, to fill a portion of the pattern, which before this displayed lobes interspersed by deep nulls. The angular and radial positions of all the roots are simultaneously adjusted so that the amplitude of each ripple in the shaped region and the height of each sidelobe in the nonshaped region are individually controlled. Applications to a cosec
2
θ × cos θ pattern and to a flat-topped beam are presented. Experimental validation is also offered.
247 citations
TL;DR: In this paper, a method is suggested to calculate a size independent fracture toughness parameter, inelastic displacements are extracted from the total displacements and the slow crack growth is included by incorporating crack closing-pressure.
230 citations
Patent•
05 Nov 1985TL;DR: In this article, the authors describe a radiotherapy machine that includes a microwave powered accelerator to produce an energetic beam of charged particles, bending and focussing magnets to parallel scan the beam in a plane and collimators to make the resulting parallel scanned beam into paraxial rays of charge particles or X-rays.
Abstract: A radiotherapy machine includes a microwave powered accelerator to produce an energetic beam of charged particles, bending and focussing magnets to parallel scan the beam in a plane and collimators to make the resulting parallel scanned beam into paraxial rays of charged particles or X-rays. The beam is intensity modulated as it is scanned to control dosage spatial distribution. The subject is moved perpendicular to the scanning plane in order to treat a 3-dimensional shape.
TL;DR: In this paper, the contrast in high resolution electron micrographs of three different thin crystals has been compared quantitatively with that predicted theoretically from separate measurements of thier electron diffraction patterns, showing that the absolute contrast in images of vermiculite is roughly 1/5th of that expected for a theoretically perfect microscope, whereas images of paraffin and purple membrane seldom reach more than 1/25th of theoretical contrast.
Patent•
30 Nov 1985
TL;DR: In this article, a punching machine is used to cut a part of a resin tape body at the outside of a slit hole to prevent the insertion of an external force, such as bending or the like.
Abstract: PURPOSE:To scarcely deform a semiconductor device and to facilitate soldering of wirings to leads on a mounting substrate by cutting the leads and supporting beam at slight outside of a slit hole thereby to allow part of a resin tape body to remain in a ring state at the outside of the hole, and inhibiting to cut the beam. CONSTITUTION:After leads 4 are adhered to a resin tape 1, a semiconductor chip 2 is aligned in a device hole 7, Au-Sn eutectic is formed by thermally press-bonding the ends of the leads 4 to the bump electrodes of the chip 2 to be connected. Then, a part III slightly outside from a slit hole 3 is cut by a punching machine, thereby forming a semiconductor device. A ringlike section 9 remaining in the hole 3 of a resin tape body 1A is operated as a function of an outer supporting ring 9 for supporting fixedly the leads 4, and the leads 4 are adhered by an adhesive 10 made of resin to the outer supporting ring 9. Thus, the leads 4 become strong against an external force, such as bending or the like.
Patent•
23 Apr 1985
TL;DR: In this article, an illumination optical arrangement comprises light source means emitting a coherent light beam, and means for forming a substantially incoherent light source from the coherent light beacon, and optical means for form a plurality of optical paths for directing the coherent beam passed through the predetermined scanning area to different secondary scanning areas.
Abstract: An illumination optical arrangement comprises light source means emitting a coherent light beam, and means for forming a substantially incoherent light source from the coherent light beam. The incoherent light source forming means includes means for periodically deflecting the coherent light beam and scanning a predetermined scanning area by the coherent light beam, and optical means for forming a plurality of optical paths for directing the coherent light beam passed through the predetermined scanning area to a plurality of different secondary scanning areas. Each of the plurality of secondary scanning areas is scanned by the periodically deflected coherent light beam.
TL;DR: In this article, the ion beam supplied by the UNILAC accelerator at GSI Darmstadt is characterized by its small emittance, the well defined mass, charge and energy of the ions and their stochastical distribution in the phase space.
Abstract: Fast heavy ions produce stable defects in most dielectrica. As examples mica, Polyethylenterephtalat and Polystyrol were irradiated with Ar, Ni, Kr, Xe and U ions in an energy range from 0.5 up to 20 MeV/u. The resulting defects were investigated by neutron and x-ray small-angle scattering. The ion beam supplied by the UNILAC accelerator at GSI Darmstadt is characterized by its small emittance, the well defined mass, charge and energy of the ions and their stochastical distribution in the phase space. In scattering experiments the system of scattering centers created by these ions causes a scattered intensity distribution which strongly depends on the orientation of the sample with respect to the unscattered neutron or x-ray beam. This dependence is investigated and explained.
TL;DR: In this article, Bernoulli-Euler theory and Bessel functions are used to obtain explicit expressions for the exact dynamic stiffnesses for axial, torsional and flexural vibrations of any beam which is tapered such that A varies as yn and GJ and I both vary as y(n + 2), where y = (cx/L) + 1; c is a constant such that c > − 1; L is the length of the beam; and x is the distance from one end of a beam.
Abstract: Bernoulli-Euler theory and Bessel functions are used to obtain explicit expressions for the exact dynamic stiffnesses for axial, torsional and flexural vibrations of any beam which is tapered such that A varies as yn and GJ and I both vary as y(n + 2), where A, GJ and I have their usual meanings; y = (cx/L) + 1; c is a constant such that c > − 1; L is the length of the beam; and x is the distance from one end of the beam. Numerical checks give better than seven-figure agreement with the stiffnesses obtained by extrapolation from stepped beams with 400 and 500 uniform elements. A procedure is given for calculating the number of natural frequencies exceeded by any trial frequency when the ends of the member are clamped. This enables an existing algorithm to be used to obtain the natural frequencies of structures which contain tapered members.
Patent•
17 May 1985TL;DR: An optical stress pulse generation and detection system for nondestructively measuring physical properties of a sample, which uses a pump beam having short duration radiation pulses having an intensity and at least one wavelength selected to non-destructively generate a stress pulse in a sample and directs the nondestructive pump beam to a surface of the sample to generate the stress pulse as mentioned in this paper.
Abstract: An optical stress pulse generation and detection system for non-destructively measuring physical properties of a sample, which uses a pump beam having short duration radiation pulses having an intensity and at least one wavelength selected to non-destructively generate a stress pulse in a sample and directs the non-destructive pump beam to a surface of the sample to generate the stress pulse. The optical stress pulse generation and detection system also uses a probe radiation beam and guides the probe beam to a location at the sample to intercept the stress pulse. The change in optical constants induced by the stress pulse is detected by observing the probe beam after it intercepts the stress pulse.
TL;DR: In this paper, an elastic beam with one-sided amplitude constraint subjected to periodic excitation is considered and compared with results given by a theoretical model based on a single mode analysis of the beam following the work of Moon and Shaw.
Patent•
30 Aug 1985
TL;DR: In this paper, a method and apparatus for determining distance from a bow to a target at which the bow is aimed in which a beam of collimated light from a laser is directed to the target and reflected to a linear photosensitive element mounted on the bow.
Abstract: A method and apparatus for determining distance from a bow to a target at which the bow is aimed in which a beam of collimated light from a laser is directed to the target and reflected to a linear photosensitive element mounted on the bow. The element and laser are positioned on the bow so that the linear position of the incident reflected beam varies with the target distance and the element produces an output indicating the position. A circuit receives that output and produces a display of the target distance.
TL;DR: In this paper, the authors reviewed the techniques and results of various experimental groups, and applications of laser-cooled atoms, in particular the possibility of confining them in electromagnetic traps, are discussed.
Abstract: Atoms in a thermal beam can be cooled, decelerated, and stopped using the radiation pressure from a nearly resonant laser beam. Several groups have already used this laser-cooling process on an atomic sodium beam. The techniques and results of the various experimental groups are reviewed, and applications of laser-cooled atoms, in particular the possibility of confining them in electromagnetic traps, are discussed.
01 Apr 1985-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the first operative silicon drift detectors for position and energy measurements are presented, and design criteria and experimental results in the laboratory and on an accelerator beam are reported, respectively.
Abstract: Semiconductor drift chambers have been recently suggested and feasibility tests performed. This paper presents the first operative silicon drift detectors for position and energy measurements. Design criteria and experimental results in the laboratory and on an accelerator beam are reported.
TL;DR: In this paper, a three-dimensional self-trapped beam connected with the rotation of the field phase is obtained, where the field intensity is ring-shaped and the field distribution has a rotating spiral character, its parameters being expressed through constants of the motion.
TL;DR: In this paper, the excitation mechanism of low-freqeuncy upstream hydromagnetic waves was studied by means of particle simulation, and the phase space bunching of beam ions by the excited waves was observed for the explanation of "gyrophased bunched" ions observed in the foreshock region.
Abstract: By means of particle simulation, we study the excitation mechanism of low-freqeuncy (0.01–0.05Hz) upstream hydromagnetic waves. Initially, we observe excitation of the right-hand polarized waves propagating parallel to the field-aligned ion beam, which is given as the free energy source. In the nonlinear stage we observed the phase space bunching of beam ions by the excited waves. We apply this bunching effect for the explanation of “gyrophased bunched” ions observed in the foreshock region.
01 Jul 1985
TL;DR: In this paper, a uniform beam element of open thin-walled cross-section is studied under stationary harmonic end excitation and an exact dynamic (transcendentally frequency-dependent) 14 × 14 element stiffness matrix is derived from Vlasov's coupled differential equations.
Abstract: A uniform beam element of open thin-walled cross-section is studied under stationary harmonic end excitation. An exact dynamic (transcendentally frequency-dependent) 14 × 14 element stiffness matrix is derived from Vlasov's coupled differential equations. Special attention is paid to the computational problems arising when coefficients vanish in these equations because of symmetric cross-section, zero warping stiffness, etc. The dynamic element stiffness matrix is established via a generalized linear eigenvalue problem and a system of linear algebraic equations with complex matrices. A static stiffness matrix is also derived and the associated consistent mass and geometric stiffness matrices are given. Modal masses are evaluated. A FORTRAN program and a numerical example are included.
Patent•
30 Oct 1985
TL;DR: In this article, three filters sets (60, 62 and 64) each include three pivotable dichroic filter elements, each element is rotatable around an axis perpendicular to the light beam in order to vary the angle of incidence and hue.
Abstract: A variable light source includes a light (14) which projects a white light beam. Three filters sets (60, 62 and 64) each include three pivotable dichroic filter elements. Each element is rotatable around an axis perpendicular to the light beam in order to vary the angle of incidence to vary the hue of the light beam. Rotation of the filter elements also varies the white light transmitted past the filter elements in order to vary the saturation of the light. The distance between the light source (26) and the reflector (28) may be varied to change the divergence of the light beam.
TL;DR: In this article, a formulation, an efficient solution procedure, a microcomputer program, and a graphics routine for an anisotropic symmetrically laminated beam finite element in cluding the effect of shear deformation is introduced.
Abstract: A formulation, an efficient solution procedure, a microcomputer program, and a graphics routine for an anisotropic symmetrically laminated beam finite element in cluding the effect of shear deformation is introduced. The emphasis of the formulation and solution procedure is for simplicity, efficiency, and easy implementation on microcomputers. The element possesses six d.o.f.'s at each of the two nodes: trans verse deflection and slope due to bending and shear, respectively, and a twisting angle and its derivative with respect to the beam axis. The formulation, solution procedure, and the program have been evaluated by performing a systematic choice of examples; whenever possible, the present solutions are compared with alternative existing solu tions.
Patent•
24 Apr 1985
TL;DR: In this article, the precise sputter etching and imaging of insulating and other targets, using a finely focused beam of ions produced from a liquid metal ion source, is described.
Abstract: An apparatus is described which makes possible the precise sputter etching and imaging of insulating and other targets, using a finely focused beam of ions produced from a liquid metal ion source. This apparatus produces and controls a submicron beam of ions to precisely sputter etch the target. A beam of electrons directed on the target neutralizes the charge created by the incident ion beam. Imaging of the target surface and ultra-precise control of the etching process is achieved by monitoring the particles that are sputtered from the target surface.
TL;DR: In this article, a nouvelle methode for le calcul de la reponse en regime stationnaire des structures amorties par frottement, which est compatible avec les codes par element fini existants, is presented.
Abstract: Developpement d'une nouvelle methode pour le calcul de la reponse en regime stationnaire des structures amorties par frottement, qui est compatible avec les codes par element fini existants. Resultats montrant, par simulation d'une poutre d'essai, que la precision de la methode est acceptable dans le cas d'un amortisseur essentiellement rigide et amelioree quand la flexibilite de l'amortisseur devient plus comparable a celle de la poutre d'essai
TL;DR: In this article, an exact stiffness matrix of a beam element on elastic foundation is formulated, and a single element is required to exactly represent a continuous part of the beam on a Winkler foundation.