Results 1 - 10 of 7016
Results 1 - 10 of 7016. Search took: 0.039 seconds
|Sort by: date | relevance|
[en] New equipments were developed in order to characterize the fracture mechanical properties of concrete. First, the wedge-splitting method according to Tschegg and Linsbauer is outlined. Then, different specimen shapes and three different loading devices with sliding and rolling friction are presented and a COD-measuring device is described. The range of application of the new test equipments for hydraulic and mechanical testing machines is pointed out. A simple table-testing machine applied for detecting fracture mechanical parameters of concrete is described, for which the above mentioned loading devices and the COD-measurement unit is used. Some test results obtained with this equipment are reported. Finally, the new equipments are compared with other facilities described in the literature. (orig.)
[de]Zur bruchmechanischen Charakterisierung von Beton und anderen zementgebundenen Werkstoffen werden neue Pruefeinrichtungen vorgestellt. Die Keilspaltmethode nach Tschegg und Linsbauer wird beschrieben und deren Anwendung auf wuerfel- und zylinderfoermige Probenkoerper mit verschiedenen Belastungseinrichtungen diskutiert. Auf die Einsatzmoeglichkeit von hydraulischen und mechanischen Pruefmaschinen sowie einer einfachen Tisch-Pruefmaschine zur Durchfuehrung der Keilspaltpruefungen mit den beschriebenen neuen Methoden wird eingegangen. Abschliessend werden die neuen Pruefeinrichtungen mit anderen in der Literatur bekannten Vorrichtungen verglichen und diskutiert. (orig.)
[en] The invention relates to an apparatus for submitting n (n>=1) test specimens of a given material to alternate tensile and compressive stresses. The apparatus comprises an excitation source whose displacement axis is horizontal, a guiding stem an extremity of which is rigidly connected to said exciter and the other extremity of which is provided with n means for fixing an extremity of each of the n test specimens. Said stem is guided in such way that it can move in free translation along a horizontal axis. This apparatus also comprises a bulk part provided with n horizontal bearings, and nozzles for injecting a pressurized gas, so that these n bearings constitute gas bearings intended for n cylindrical masses each with a horizontal axis. Said masses are provided, on their side facing said stem, with a fixation means of the other extremity of one of the n test specimens
[fr]L'invention concerne un dispositif pour soumettre n (n>=1) eprouvettes d'un materiau a des efforts alternes de traction et de compression. Ce dispositif comprend une source d'excitation dont l'axe de deplacement est horizontal, une tige de guidage dont une extremite est solidaire dudit excitateur et dont l'autre extremite est munie de n organes de fixation de l'une des extremites des n eprouvettes. Ladite tige guidee de telle facon qu'elle puisse se deplacer librement en translation selon un axe horizontal. Le dispositif comprend aussi une piece massive comportant n paliers horizontaux et munie de buses d'injection d'un gaz sous pression; ces n paliers constituent ainsi des paliers a gaz pour n masses cylindriques admettant chacune un axe horizontal. Lesdites masses comportent sur leur face tournee vers ladite tige un organe de fixation de l'autre extremite de l'une des n eprouvettes
[en] Highlights: • The yield-point phenomenon (YPP) was analysed in relation with cyclic plasticity. • Uniaxial cyclically-loaded specimens made of EN 42CrMo4 were analysed in normalized and tempered state. • Digital image correlation was used for observing the strain field of specimens during monotonic and cyclic experiments. • In specific conditions, the YPP is present during the whole lifetime of uniaxial specimens. • The YPP can affects the lifetime of a cyclically-loaded specimen, when material exhibits cyclic softening. The article presents the influence of the yield-point phenomenon (YPP) on the cyclic plasticity of the uniaxial cyclically-loaded specimens based on observation of stress–strain responses and imaging of strain fields. The phenomenon and its dependence on cyclic material hardening or softening was studied through experiments conducted on the low-alloy EN 42CrMo4 steel in its normalised state (184 HV), which exhibits cyclic hardening, and in its tempered state (296 HV), which is subject to cyclic softening. The results of the study express the influence of the YPP on cyclic plasticity through inhomogeneous strain field when specimens are loaded with strain amplitudes within the yield plateau. The YPP is well expressed in uniaxial cyclic experiments of cyclically softening material.
[en] A process is described for stress relieving seamless metal tubes having undergone truing-up. In this process the tubes are maintained at near ambient temperature for not less than three minutes, during which time they are subjected to an internal pressure of between 0.8 Pc and Pc, Pc being the critical pressure beyond which the tube undergoes plastic deformation through its entire thickness. The elastic limit of the tube to be processed is determined by a mechanical test, the critical pressure Pc is determined by the relation Pc=R 0.2 Log r1/r0 where R 0.2 is the elastic limit, r1 the external radius and r0 the internal radius of the tube, and an internal pressure is maintained in the tube, this internal pressure being in the 0.8 Pc and Pc bracket. Water under pressure is pumped into the tube. In the case of very long curved tubes for nuclear power station steam generators, these tubes are fixed to an installation at hydrostatic pressure
[fr]On presente un procede de detensionnement de tubes metalliques sans soudure ayant subi une operation de dressage, caracterise par le fait qu'on soumet pendant une duree au moins egale a 3 mn les tubes maintenus a une temperature voisine de la temperature ambiante, a une pression interne comprise entre 0,8 Pc et Pc, Pc etant la pression critique au-dela de laquelle le tube subit une deformation plastique sur toute son epaisseur. On determine par un essai mecanique la limite elastique du tube a traiter, on determine la pression critique Pc par la relation Pc=R 0,2 Log r1/r0 ou R 0,2 est la limite elastique, r1 le rayon exterieur et r0 le rayon interieur du tube, et on maintient une pression interne dans le tube, cette pression interne etant comprise entre 0,8 Pc et Pc. On envoie dans le tube de l'eau sous pression. Dans le cas de tubes cintres de grandes longueurs pour generateurs de vapeur d'une centrale nucleaire, on fixe ces tubes sur une installation d'essai a la pression hydrostatique
[en] This report describes the results of CEGB participation in a round-robin to validate the European Group on Fracture (EGF) recommendations for determining the fracture resistance of ductile materials. Tests were performed on medium and high toughness materials and the results used to assess the performance of the EGF procedure. Several areas of concern were identified and where possible solutions are proposed. (author)
[en] In this paper the method of damage measuring of metal structure for the creep is proposed. In contrast to other methods, it allows to carry the measuring of this damage in the process of test for creep without unloading and cooling of specimens. Experimental damage curves for creep are obtained as a result of calculating processing of test data by use the suggested method. The analysis of these curve allows to obtain a conclusion that the material damage for rupture is monotonically decreasing function of applied stress. This conclusion is experimental confirmation of the theoretical results, obtained earlier. (orig.)
[en] We recently proposed a theory of mechanism-based strain gradient (MSG) plasticity to account for the size dependence of plastic deformation at micron- and submicron-length scales. The MSG plasticity theory connects micron-scale plasticity to dislocation theories via a multiscale, hierarchical framework linking Taylor's dislocation hardening model to strain gradient plasticity. Here we show that the theory of MSG plasticity, when used to study micro-indentation, indeed reproduces the linear dependence observed in experiments, thus providing an important self-consistent check of the theory. The effects of pileup, sink-in, and the radius of indenter tip have been taken into account in the indentation model. In accomplishing this objective, we have generalized the MSG plasticity theory to include the elastic deformation in the hierarchical framework. (c) 2000 Materials Research Society
[en] Crush tests were performed on two AECL F112 packaging specimens, two simulated AECL-CRNL 4H packaging specimens, and on empty steel drums. The 9 m drop test was carried out on two simulated AECL-CRNL 4H packaging specimens for comparison with the effects of the crush test. The tests were filmed using high speed photography and 35mm still photographs
[en] This work was conducted under PLN-4560, “GTRI Mechanical Property Characterization Test Plan,” which contains additional requirements and instructions for testing. The following report presents details of the testing system, testing methods, and mechanical properties determined from the test data.
[en] Operational strength and fatigue life reliability of trolleybus and bus bodies are usually assessed by computational methods in combination with selected tests. The latter include test runs of vehicles on real routes or on specially designed tracks, tests on complete vehicles under model test conditions and laboratory tests on selected materials, parts and subassemblies. This paper describes a method of experimental investigation of operational strength and reliability developed and applied at the Central Research Institute Skoda for public-transport road vehicles made in Czechoslovakia. (orig.)