Change In Deflection Research Articles

Principles of inelastic deformation of metals under cyclic loading in air and liquid media

This paper is devoted to a study of the principles of inelastic deformation of iron and steels during fatigue in air, in an inactive (purified dry liquid petrolatum) medium, in a surface-active (2% solution of oleic acid in liquid petrolatum) medium, and in corrosion-active (distilled water and 3% solution of NaCI in water) media. The investigation was done according to the method described earlier [4], which permitted the fatigue process to be analyzed by continuously recording the change in the sample deflection.

Stress and anxiety neurosis: A study of recovery

Thirty seven patients with Anxiety Neurosis were selected from the patients attending the Day Centre, Whitchurch Hospital, Cardiff, between April 1972 and June 1973, following formal diagnosis of a neurotic Anxiety State by a consultant psychiatrist. A relatively homogeneous sample of subjects was selected using the following criteria to confirm diagnosis: apprehension, palpitations, panic attacks, excessive perspiration, inability to relax, and feelings of impending disaster. Patients were excluded from the parent population if they had been treated by E.C.T. in the previous six months, or had had a leucotomy, gross agitation, physical tremors, congenital blindness, or an abnormally low I.Q. Twenty-eight patients were subjected at weekly intervals to a series of individually tailored stimuli composed of stressful events pertaining to each patient's life history. Skin conductance variables (i.e. maximum deflection, baseline change, and frequency of spontaneous fluctuations) heart rate variables (i.e. changes in mean and peak heart rate), mood and personality, (E.P.I. measures of E. and N.) were examined for changes associated with recovery. It was predicted that no significant change in trend would occur in the physiological responses of non-recoverers over time, whereas there would be significant positive trends in those who recovered. The results were contrary to prediction, as significant negative trends were displayed in four out of five physiological measures in the non-recovery group, and no significant trends were recorded for recoverers, despite a tendency towards a positive trend in all physiological measures. Comparison with a control group (non-experimental) indicated that habituation effects could not account for the outcome, and also that the procedure per se had no influence on the speed of recovery. Mood scores, subjective ratings of distress, and ratings of improvement, confirm that physiological changes were related to recovery from Anxiety Neurosis. Recovery was also found to be linked with a decrease in N. scores and an increase in E. scores. It is possible to distinguish the physiological responses of recoverers and non-recoverers from Anxiety Neurosis on the basis of their reaction to highly stressful and relevant stimuli in terms of change in maximum deflection and spontaneous fluctuation frequency. The recovery curves should be generalisable to all groups of Anxiety State patients regardless of the type of treatment received. Support for the cognitive mediation of stress during Anxiety Neurosis is presented.

Study of the precritical deformation of cylindrical shells made of inorganic glass with initial geometrical imperfections on subjecting to external hydrostatic pressure

1. We have proposed a method which enables us, by considering the relative deviations of the outer and inner sides of the cross sections of cylindrical shells, to determine their average radius and thickness, together with the magnitude and distribution of the initial geometrical imperfections. 2. Under the influence of hydrostatic pressure, the initial shape of the cross section in silicate glass cylindrical shells usually undergoes a considerable rearrangement. In shells of ideal or nearly ideal initial geometry, the critical loss-of-stability shape corresponds to that predicted by the linear theory. In geometrically imperfect shells the change in the initial deflection develops in the following way: In the zones having the maximum initial deflection, the latter increases, while in the zones intermediate between those with the maximum initial geometrical imperfections a complete rearrangement of the initial equilibrium shape may occur. 3. Loss of stability of the equilibrium state in cylindrical glass shells leads to the exhaustion of their carrying capacity. 4. Until recommendations soundly based on a great deal of experimental data have been developed, the stability of smooth inorganic glass cylindrical shells having a maximum deflection of Wmax≤0.3H and H/R=0.06–0.07 may conveniently be estimated by reference to the upper critical load.

Aging induced shape instability in an elastically bent uranium + 7.5 wt pct niobium + 2.5 wt pct zirconium alloy

The uranium +7.5 wt pct niobium +2.5 wt pct zirconium alloy when quenched from 1073 K was found to exist at room temperature as a metastable phase which was a slight tetragonal distortion of the elevated temperature body-centered-cubic (bcc) phase. Flat, asquenched specimens have been elastically deformed in four-point bending to maximum outer fiber stresses below the stress required for plastic deformation to occur but into a range of stress where pseudoelastic behavior has been observed. Aging of these elastically bent specimens in an oil bath at 423 K, while constrained by the bending jig, resulted in a permanent deflection and shape change. Further isothermal aging, after removal from the bending apparatus, caused increasing deflection and continued shape instability in spite of the absence of the applied load. X-ray examination of samples cut from a bent and aged specimen revealed important preferred orientation and lattice parameter differences between the tension and compression regions and the high and low stress parts of the specimen. These observations are described and compared to previous findings on quenched samples of this alloy that had been either deformed separately or aged separately. A rationalization of the shape instability is presented. Elastic twin nucleation and growth, preferred orientations, solute segregation and the interplay of all these seem to be involved.

Static behavior of the krasnoyarsk dam under design load conditions

1. The results of all types of field observations show that the dam operates normally under the design loads. Changes in settlements, tilts, deflections, temperature, stresses, and percolation are regular in nature, being determined by changes in the reservoir water level and air temperature and by the deformation properties of the foundation and structure. 2. The values of the moduli of elasticity of the concrete dam and rock obtained from the measured horizontal and vertical displacements indicate a good quality of concrete in the structure and good sealing operations, as well as the effectiveness of the measures taken to stabilize weakened portions of the rock foundation. 3. The principal compressive stresses on the upstream face of the dam, determined from the strains measured in the concrete, in all cases are greater than the 0.25 γH stipulated by the existing standards SN 123-60; as a rule they are also greater than the calculated values used in the plan owing to the component of the technological stresses during the construction and construction-operating periods. The principal stresses on the downstream face of the dam have a considerable seasonal variation, reaching 30–50 kg/cm2. The average values of the compressive stresses on the downstream face are equal to or greater than the calculated. 4. The measured elastic displacements of the dam crest agree well with analogous quantities obtained by calculation, if the effect of the weight of the water on the reservoir bed is taken into account in the calculation. 5. The forecasted displacements of the dam crest can serve as criteria of the static behavior of the structure under operating conditions.

Minimum Weight Design of Finite Element Structures

Design algorithms for obtaining the minimum weight of finite element structure are presented. The procedures are based upon approximating the structural behavior as a function of the reciprocal of the characteristic crosssectional property of the finite elements. In addition, approximations based upon the compatibility equations are employed. This results in simpler and generally more accurate approximations of the deflection and stress changes as compared to present procedures which utilize the size variables and the equilibrium equations. Algorithms based upon linear programming utilizing linear constraints obtained either from the global equilibrium or compatibility equations plus a gradient search procedure with segmented linear constraints are developed. The efficiency of the linear programming with linear (equilibrium) constraints, which utilizes available digital subprograms, was demonstrated by comparison of solutions of 3- and 10-bar truss problems presented in the literature. All solutions were of equal or less weight than published results and generally were obtained with fewer redesign cycles. The other algorithms are potentially more efficient. They require, however, further development and demonstration.

Plane Bending Fatigue of Thermoplastic Materials

Owing to the thermal and viscoelastic natures, the mechanical properties of thermoplastics closely depend on the various factors such as testing temperature, test speed and so on. In fatigue under repeated stresses, the materials are more sensitive to such factors and sometimes show the considerable temperature rise which generally causes the reduction of fatigue strength.Two kinds of thermoplastic materials were prepared, namely Polymethylmethacrylate (PMMA) sheet of 4mm in thickness and Polycarbonate (PC) sheet of 3mm in thickness. Their glass transition temperatures are 120°C and 150°C respectively, and the elastic modulus of PMMA is 1.5 times larger than that of PC.They were fatigued in plane bending with the test speed of 1800rpm to obtain the dependencies of their fatigue strengths on the testing temperature and pause periods during fatigue test and to examine the relations between the fatigue behavior and the temperature rise of specimen itself, deflection change during fatigue test and fracture surface.At high stress levels PMMA failed in cyclic thermal softening by extraordinary temperature rise resulting from the internal damping, but at low levels it fractured by fatigue crack propagation. As for PC, the temperature rise was relatively so small that all the failures took place by fatigue crack propagation over the wide range of stress levels. Moreover, the fatigue behavior of PMMA was strongly affected by the test conditions, especially thermal conditions. The fatigue life decreased as the testing temperature rised but it was prolonged by the pause during fatigue. On the other hand, the fatigue behavior of PC was not so much influenced by the above conditions as PMMA. These differencies in fatigue behavior correspond to that in temperature dependency of mechanical properties of these materials.

Electron irradiation dilatation in SiO2

Negative dilatation (shrinkage) induced by 10-keV electron bombardment of SiO2 films thermally grown on Si has been studied. Measured deflection changes in continuous SiO2 bridges etched following irradiation showed a maximum shrinkage of [inverted lazy s] 0.8%, which occurred at 0.2 C/cm2, followed by a slight expansion, and subsequent saturation at higher exposures. Exposures up to 3 C/cm2 were utilized. Isochronal annealing studies show the activation energy for recovery to be approximately 1 eV with 2% recovery occurring in 1 h at 400°C.

REGIONAL INTEGRATION AND TRADE LIBERALIZATION IN LATIN AMERICA

JCMS: Journal of Common Market StudiesVolume 10, Issue 1 p. 58-77 REGIONAL INTEGRATION AND TRADE LIBERALIZATION IN LATIN AMERICA Bela Balassa, Bela Balassa *Professor of Political Economy at the Johns Hopkins University.Search for more papers by this author Bela Balassa, Bela Balassa *Professor of Political Economy at the Johns Hopkins University.Search for more papers by this author First published: September 1971 https://doi.org/10.1111/j.1468-5965.1971.tb00644.xCitations: 6Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume10, Issue1September 1971Pages 58-77 RelatedInformation

電解析出γ型マンガンのα型マンガンへの変態について

The electrodeposition of γ-manganese from a sulphate bath containing 150 g/L of (NH4)2SO4 and 40 g/L of Mn++ was performed. The transformations of the γ-manganese to α-manganese were studied by means of measurements of the deflection of the deposit with a contractometer and of the change in the magnetic susceptibility of the deposit. X-ray observations were made to check the relation between the deflection of the deposit and the change in crystal structures of the deposit. The results obtained are summarized as follows:(1) Change of the contractile deflection of the electrodeposited γ-manganese on being exposed in air corresponds closely to the transformation from γ-to α-manganese. The rate of the transformation was estimated from the results of the deflection measurements, and the activation energy of the transformation obtained is 22.3 kcal/mol.(2) The magnetic susceptibility of the γ-manganese is found to be 7.15×10−6 e.m.u./g and that of the α-manganese transformed from electrodeposited γ-manganese is 9.67×10−6 e.m.u./g. The rate of the transformation was obtained from the measurements of magnetic susceptibility, and the activation energy of the transformation was estimated to be 21.4 kcal/mol, which is close to 21.2 kcal/mol obtained from the measurement of electric resistivity during the transformation by Potter et al.(3) The rates and activation energies of the transformations in the γ-manganese and the mixture of γ-and α-manganese electrodeposited from the baths containing a small amount of Na2SeO4 are almost the same as those of the γ-manganese electrodeposited from the bath without Na2SeO4.(4) The results of deflection, magnetic susceptibility and X-ray measurements do not show the presence of β-manganese at any stages of the transformation and it may be concluded that β-manganese is not formed as an intermediate product during the transformation from γ to α.

The Arrangement of Harmonium

But contrasts arise between the poems of Harmonium as well as within them. By juxtaposing different subjects, styles and assulmnptions, by placing recent poems in between old ones like flowers in last month's newspapers, Stevens extended his use of novelty, whimsy and contrast from individual poems to their arrangement in his book. The contrasts produced by the arrangement of the poems in Harmonium are of all kinds: antithesis, contradictions, changes of tone or subtle deflections of points of view may delight and confuse the reader. But while many types of contrast appear in the book, adjacent poems are usually contrasted in some single specific way. In order to understand how Harmonium was put together, how its arrangement may affect our reading, and what aid a critic may derive from other printings of Harmonium poems, let us examine the extraordinarily clear contrast which arises between Banal Sojourn and Depression before Spring, poems adjacent in Harmonium which call for different responses to the word green :

Motor performance and sensory-evoked potentials

Averaged evoked potentials (EP) to tones were determined for fifteen subjects in three tasks which were designed to evaluate the effects of motor response, of withholding a response and of different response latencies. With the influence of eye movement minimized, it was found that the various deflections of the sensory EPs were affected differently as follows: 1. 1. Withholding a response produced a significantly larger P 3 deflection. The amplitude of this deflection was negatively correlated with reaction time (RT). 2. 2. Stimuli to which overt motor responses were subsequently made produced a negative shift in deflections N 1, P 2 and N 2, but there were no significant changes in deflections P 1, P 3 and N 3. 3. 3. No effects which could be ascribed to specific time characteristics of the tasks ( e.g., simple versus choice RT) were found and no effects could be attributed to the overt motor response or its immediately preceding EMG activity. The data were interpreted to mean that the negative shift in N 1, P 2 and N 2 is related to the development of an excitatory state associated with the intention to respond to the stimulus and that increased positivity in P 3 is uniquely related to the act of withholding a response to the stimulus when rapid action is required. No effects on the averaged EP were observed that could be attributed unequivocally to occurrence of overt motor response itself.

Degradation of Polystyrene Caused by Dynamic Fatigue

Degradation of polystyrene caused by dynamic fatigue combined with irradiation of ultraviolet rays is here under reported.The fatigue behavior during the fatigue test, i. e. the dynamic deflection and temperature rises of the specimens, were also observed with the method as was reported in the previous paper.3) The degradation was determined by infrared and ultraviolet spectroscopy, X-ray diffraction, differential thermal analysis, thermogravimetric analysis and solution viscosity. The fatigue testing machine used here was the modified one of ASTM D-671-63T method B. The specimens were made of G. P. grade polystyrene by injection for the ASTM type. The condition of the sample prepapation are as follows: original, irradiation only of ultraviolet rays (48, 167hrs), fatigue only (48, 167hrs), irradiation (48, 167hrs) followed by fatigue (48, 167hrs) and irradiating fatigue (48, 167hrs), their alternating loads being 2.5kg for 48hrs and 1.6kg for 167hrs.The results of the experiment show that for G. P. polystyrene, the degradation caused by the dynamic fatigue and the irradiation of ultraviolet rays are not remarkable, though photo-oxidation is observed in the case of polystyrene film, and so the photo-degradation may be limited to the specimen surface. As to the fatigue behavior of polystyrene, the dynamic deflection change was small and this phenomenon agrees with the small degradation observed in the present experiment.

An Approach to Determining Water Saturation in Shaly Sands

An Approach to Determining Water Saturation in Shaly Sands

Effect of Redirectors, Refocusers, and Mode Filters on Light Transmission Through Aberrated and Misaligned Lenses

The field distortion of a beam propagating through a sequence of identical, misaligned and slightly aberrated lenses is calculated as a perturbation of the Gaussian beam that would propagate in the absence of aberration. It is found that most of the converted power goes to the first and second modes. They produce deflection and spot-size change of the ideal beam, respectively. The power coupled to modes higher than the second deform the Gaussian profile. In general, the mode conversion per unit length of guide can be reduced by making the spot size small and by avoiding in-phase coupling at every lens. This last condition is achieved by choosing the period of oscillation of the beam different from an integer number of lens spacings. Before the beam becomes too distorted, the converted modes must be eliminated. Power in the first and second modes can be reconverted loss-lessly to the fundamental Gaussian beam by means of servoloops that redirect and refocus the beam. If refocusers are not used, the power in the second mode, as well as the power in the higher-order modes must be absorbed in mode filters such as irises. For lenses with fourth-order aberration such that at a beam half-width distance from the center the focal length departs δ percent from ideal, the following typical results are obtained: In a guide in which the distance between the beam and guide axes is a constant plus a sinusoid, the converted power is proportional to δ2, to the fourth power of the amplitude of the sinusoid and to the square of the number of lenses, but is roughly independent of the curvature of the guide axis. On the other hand, in a guide in which the distance between the beam and guide axes is a constant plus a random quantity the converted power is proportional to δ2, to the square of the guide curvature, to the mean square of the random deviation, and to the number of lenses. Fof &delta =1 percent, a 1 power conversion to the second mode occurs is typical examples, after a few of lenses, and the order of magnitude of mode conversion is 0.001 dB/lens. Most of that power is in the second mode and can be recovered with refocusers.

Electroencephalographic Differences between Resting and Mental Multiplication

The average frequency of 30 sec. of EEG tracing for two states, resting and mental multiplication (thinking), was determined for 20 Ss by counting each visually detectable change in pen deflection regardless of amplitude. (1) Thinking gave higher average activity scores than resting. (2) The difference in average activity between thinking and resting was greatest in the two frontal and left temporal areas and it was significantly different from the differences in the other areas. (3) In the resting state there was a difference between left and right frontal and temporal areas (which increased while thinking) in contrast with a left-right symmetry of the other areas tested. These findings were interpreted as representing characteristic average activity for the areas and condiions tested and were offered as evidence for the differential utilization of brain areas in the given tasks.

Studies of Crack Widths and Deformation under Sustained and Fatigue Loading

In connection with partial prestressing, cracks may develop and excessive deformation may take place. It is, therefore, essential to investigate safe limits of the maximum width of cracks to ensure freedom from corrosion of the steel and from excessive deflection. In Fig. 1 the relationship between the deflection and concrete stress at the tensile face of a beam is illustrated. The load-deflection diagram is shown in a simplified manner comprising two straight lines: one based on the calculated deflection of a homogeneous section and the other parallel to the calculated ,deflection of a cracked section computed using the appropriate value •of n corresponding to the modular ratio of the actual E-value of the -steel and concrete. In fact, this deflection curve will be slightly rounded off near the change of incline in deflection beginning from the load at which micro-cracks develop. This corresponds to the tensile strength, i.e., a tensile stress of, say, 400 to 600 psi for high strength concrete; but the load at which the cracks become visible to the unaided eye is much higher and approximates the point at which the change in deflection occurs in the

Effects of Long-Time Loads on Prestressed Concrete Beams

Abstract : Thirty post-tensioned concrete beams were loaded for 10 to 12 years, and changes in deflections, prestressing forces, and concrete strains were recorded. All of the beams were simply supported on a 40-foot span. Twenty-two of the beams were straight and had an I cross-section. Eight of these were prestressed with cables. The other fourteen were prestressed with high-strength steel bars, and eight of these beams were grouted after being post-tensioned. The twenty-two I-beams were subjected to loads varying in magnitude from dead load only to dead load plus 1.5 design live load. Eight of the beams had a gabled shape with a hollow-box cross section and were post-tensioned with wires running straight through. Six of these beams were uniformly loaded with concrete weights to provide four different loading conditions. The beams with no live loads continued to deflect upward for about 1 year. Their total camber was about 2.1 times their initial camber due to prestressing. The loaded beams continued to deflect downward for several years. In 6 1/2 years the I-beams had undergone about 94% of their total deflection due to live loads, and the hollow-box beams had reached their maximum. The maximum midpoint deflections due to live loads were from 2.2 to 2.8 times the initial deflections due to those loads. Loss of prestress was a function of the magnitude of the sustained loads. It was highest for beams with no live loads, reaching its maximum of 24% in 7 years.

Rotating Bending Fatigue Tests on Ni-Cr-Mo Steel in the Plastic Range

The constant stress and the constant deflection test were carried out of the rotating and bending fatigue of Ni-Cr-Mo steel cantilever in the plastic range at the frequency of 62rpm and at different temperatures, respectively at room temperature, at 350°C and at 550°C. In the constant stress test, the change of vertical and horizontal deflection at the loading end of the test specimen was observed. In the constant deflection test, the change of stress was also observed. The test results were discussed and compared with those obtained on the 0.35% carbon steels reported in the previous issue.The main conclusions of the results are as follows:1) It has been found in the constant stress test that the fatigue life is longest at room temperature, and falls respectively at 350°C and at 550°C. In the constant deflection test the fatigue life is approximately equal both at room temperature and at 350°C but remarkably falls at 550°C.2) The changes of deflection in the constant stress test and changes of stress in the constant deflection test have shown difference according to the temperature. On the whole they show opposite tendency.3) These results in both the tests have been compared based on the static bending test. The constant deflection is found stronger than the constant stress both at room temperature and at 350°C, but reverse at 550°C.

洋白圧延材の異方性と低温焼鈍効果

The changes in hardness, elastic modulus and bending deflection with the rolling reduction and low-temperature annealing of nickel silver were measured on the specimens cut out parallel and transverse to the rolling direction of the sheet. And the results were considered in relation to the rolled structure.The anisotropies become more remarkable as the rolling reduction exceeds 50%, and in this region, the measured values are always higher in the transverse direction than in the parallel direction. Perhaps, this may be due to the development of the rolling texture in the face-centered cubic system and to the appearance of the flaw-like strain markings developed transverse to the rolling direction. The low-temperature annealing increases the values of hardness and elastic modulus to attain the maximum values at 350°C. Also, the greater the rolling reduction is, the higher the increasing ratio becomes. The change in hardness due to the low-temperature annealing is greater as the grain size reduces, wherease the change in elasticity is hardly affected by the grain size. The process of anneal-hardening at each temperature does not show the two-stage hardening which has been observed in the α-brass sheet, but follows a simple and smooth process.No difference can be observed between the as cold-rolled and as anneal-hardened microstructures, although some structural changes of a kind of polygonization have been found in α-brass after low-temperature annealing. The results of bending deflection test correspond with those of elastic modulus.