Ultrasonic Inspection of Bridge Hanger Pins

2000 ◽  
Vol 1697 (1) ◽  
pp. 19-23 ◽  
Author(s):  
B. A. Graybeal ◽  
R. A. Walther ◽  
G. A. Washer
Keyword(s):  
Nondestructive Evaluation ◽  
Cross Section ◽  
Ultrasonic Inspection ◽  
Shear Plane ◽  
Transverse Cracks ◽  
Bridge Structures ◽  
Reliable Methods ◽  
Shear Planes

Ultrasonic inspection is currently one of the most common and reliable methods used in the inspection of hanger pins in pin-and-hanger bridge structures. Recently, a pin-and-hanger connection on a heavily traveled truck route in the Midwest showed visual indications of being deficient. Field contact ultrasonic inspections were performed on the remaining pin connections. The field inspections indicated that a number of the pins contained cracks or significant wear grooves at the pin shear planes, or both. These pins were replaced and sent to the FHWA’s Nondestructive Evaluation Validation Center for further testing in an ultrasonic immersion tank. The results of the contact and immersion tank ultrasonic studies were nearly identical. Both methods found two pins that contained transverse cracks at the level of a shear plane, with one of these cracks encompassing a majority of the pin cross section. Clearly, for the conditions found in the study, field contact ultrasonics can accurately locate defects in hanger pins.

scholarly journals The Role of Debris-Rich Ice in Flow Near the Margins of Glaciers (Abstract)

1986 ◽  
Vol 8 ◽  
pp. 201 ◽  
Author(s):  
R.W. Baker
Keyword(s):  
Shear Plane ◽  
Conveyor Belt ◽  
Physical Geography ◽  
Supporting Evidence ◽  
Ice Caps ◽  
Considerable Controversy ◽  
Flow And Sediment Transport ◽  
The Subject ◽  
Shear Planes

The margins of many ice sheets and ice caps are marked by the presence of alternating layers of debris-laden and clean ice. The role of this ice in flow and sediment transport near the margins of glaciers has been the subject of considerable controversy between glacial geologists and glaciologists for over three decades. Glacial geologists (Goldthwait, 1951, 1960, 1971, 1975; Bishop, 1957; Souchez, 1967, Boulton, 1970, 1972; Hambrey, 1976) commonly refer to the debris-bearing ice bands as “thrust planes” or “shear planes”, apparently seeing them as reverse faults which transport rock debris from the glacier bed to the surface in a “conveyor-belt-like” manner (Goldthwait, 1975, p. 192). As supporting evidence for the shear-plane mechanism, glacial geologists have offered only qualitative observations and none seem to have actually observed it in action. Glaciologists on the other hand, particularly Weertman (1961), Hooke (1968; 1973), and Hooke and Hudleston (1978), have objected to this concept on physical grounds and have presented convincing arguments for doubting that it is mechanically sound. In spite of the controversy surrounding it, the shear-plane mechanism has gained wide acceptance among geologists and physical geographers and has been perpetuated in recent years through a number of popular introductory geology and physical geography textbooks (e.g. Embleton and King, 1975; Judson, Deffeyes, and Hargraves, 1976; Leet, Judson, and Kauffman, 1978; Press and Siever, 1982; Hamblin; 1982).

scholarly journals New modular oxide structures using lone pair cations as "chemical scissors"

2014 ◽  
Vol 70 (a1) ◽  
pp. C227-C227
Author(s):  
Maria Batuk ◽  
Dmitry Batuk ◽  
Artem Abakumov ◽  
Joke Hadermann
Keyword(s):  
Oxygen Deficiency ◽  
Lone Pair ◽  
Complex Oxides ◽  
Shear Plane ◽  
Structure Type ◽  
Twin Plane ◽  
Coordination Environment ◽  
Crystallographic Shear ◽  
New Compounds ◽  
Shear Planes

"It is known that lone pair cations, such as Bi3+ or Pb2+ have a flexible coordination environment that enables them to operate as ""chemical scissors"". Their flexibility reduces the strain that would otherwise be present at the interfaces separating structure modules. We have found that in complex oxides it allows many variants of interfaces, for example crystallographic shear planes or (non)conservative twin planes in structures, enabling the synthesis of new structural families. A common characteristic for all these new compounds is the presence of magnetical frustration. As a first example, this concept allowed to introduce crystallographic shear planes into the perovskite structure, a feat that was considered highly unlikely before. This allowed to generate a new anion deficient perovskite based homologous series AnBnO3n-2 (n = 4 - 6). There is magnetic frustration at the crystallographic shear plane separating the perovskite blocks, due to competing FM and AFM interactions. Also incommensurately modulated perovskites can be obtained, for example (Pb,Bi)1-xFe1+xO3-y. These arise by replacing Bi3+ with Pb2+, which introduces an oxygen deficiency, which is then accommodated by periodically spaced CS planes to reduce the coordination of the A-cations at the interface. The flexible coordination environment of Bi3+ and Pb2+ makes them ideally suited for these A cation positions. Other possibilities were encountered in BiMnFe2O6 and Bi4Fe5O13F. In BiMnFe2O6 the Bi3+ induces the existence of a non-conservative twin plane. The result is a new structure type with hcp structured modules. In Bi4Fe5O13F, the Bi3+-cations separate layers with magnetically frustrated Cairo lattices."

Post-Processing of Phased-Array Ultrasonic Inspection Data with Parallel Computing for Nondestructive Evaluation

2013 ◽  
Vol 33 (3) ◽  
pp. 342-351 ◽  
Author(s):  
Xuefei Guan ◽  
Jingdan Zhang ◽  
S. Kevin Zhou ◽  
El Mahjoub Rasselkorde ◽  
Waheed A. Abbasi
Keyword(s):  
Parallel Computing ◽  
Nondestructive Evaluation ◽  
Phased Array ◽  
Ultrasonic Inspection ◽  
Post Processing ◽  
Inspection Data

Shear Plane Theories of Hot and Cold Flat Rolling

1964 ◽  
Vol 6 (3) ◽  
pp. 219-235 ◽  
Author(s):  
J. W. Green ◽  
L. G. M. Sparling ◽  
J. F. Wallace
Keyword(s):  
Cold Rolling ◽  
Metal Surface ◽  
Hot Rolling ◽  
Upper Bound ◽  
Coulomb Friction ◽  
Shear Plane ◽  
Experimental Results ◽  
Flat Rolling ◽  
Work Done ◽  
Shear Planes

The shear plane theory of hot rolling of thick stock, due to Green and Wallace, is extended to hot and cold flat rolling. Values calculated from the hot rolling theory compared satisfactorily with the theory of Sims and the experimental results of Wallquist. The cold rolling theory is similarly satisfactory in comparison with the experimental results of Ford and it is anticipated that the theory will be more accurate than that of Bland and Ford for small R/h ratios and large reductions. Examples of calculation of load and torque for rolling are given in Appendixes for both Coulomb friction and sticking and shearing at the metal surface and it is shown that both conditions may occur and be taken into account concurrently. A method of determining the total torque is given which is derived from an upper bound to the work done on shear planes which are shown to have the same configuration as that chosen in the analysis of forces.

scholarly journals Consequences of viscous anisotropy in a deforming, two-phase aggregate. Why is porosity-band angle lowered by viscous anisotropy?

2015 ◽  
Vol 784 ◽  
pp. 199-224 ◽  
Author(s):  
Yasuko Takei ◽  
Richard F. Katz
Keyword(s):  
Cross Section ◽  
Laboratory Experiments ◽  
A Priori ◽  
Shear Plane ◽  
High Porosity ◽  
Anisotropic Model ◽  
Maximum Compressive Stress ◽  
Two Phase ◽  
The Difference ◽  
Do So

In laboratory experiments that impose shear deformation on partially molten aggregates of initially uniform porosity, melt segregates into high-porosity sheets (bands in cross-section). The bands emerge at $15^{\circ }$–$20^{\circ }$ to the shear plane. A model of viscous anisotropy can explain these low angles whereas previous simpler models have failed to do so. The anisotropic model is complex, however, and the reason that it produces low-angle bands has not been understood. Here we show that there are two mechanisms: (i) suppression of the well-known tensile instability, and (ii) creation of a new shear-driven instability. We elucidate these mechanisms using linearised stability analysis in a coordinate system that is aligned with the perturbations. We consider the general case of anisotropy that varies dynamically with deviatoric stress, but approach it by first considering uniform anisotropy that is imposed a priori and showing the difference between static and dynamic cases. We extend the model of viscous anisotropy to include a strengthening in the direction of maximum compressive stress. Our results support the hypothesis that viscous anisotropy is the cause of low band angles in experiments.

scholarly journals The Role of Debris-Rich Ice in Flow Near the Margins of Glaciers (Abstract)

1986 ◽  
Vol 8 ◽  
pp. 201-201 ◽  
Author(s):  
R.W. Baker
Keyword(s):  
Shear Plane ◽  
Conveyor Belt ◽  
Physical Geography ◽  
Supporting Evidence ◽  
Ice Caps ◽  
Considerable Controversy ◽  
Flow And Sediment Transport ◽  
The Subject ◽  
Shear Planes

The margins of many ice sheets and ice caps are marked by the presence of alternating layers of debris-laden and clean ice. The role of this ice in flow and sediment transport near the margins of glaciers has been the subject of considerable controversy between glacial geologists and glaciologists for over three decades.Glacial geologists (Goldthwait, 1951, 1960, 1971, 1975; Bishop, 1957; Souchez, 1967, Boulton, 1970, 1972; Hambrey, 1976) commonly refer to the debris-bearing ice bands as “thrust planes” or “shear planes”, apparently seeing them as reverse faults which transport rock debris from the glacier bed to the surface in a “conveyor-belt-like” manner (Goldthwait, 1975, p. 192). As supporting evidence for the shear-plane mechanism, glacial geologists have offered only qualitative observations and none seem to have actually observed it in action. Glaciologists on the other hand, particularly Weertman (1961), Hooke (1968; 1973), and Hooke and Hudleston (1978), have objected to this concept on physical grounds and have presented convincing arguments for doubting that it is mechanically sound. In spite of the controversy surrounding it, the shear-plane mechanism has gained wide acceptance among geologists and physical geographers and has been perpetuated in recent years through a number of popular introductory geology and physical geography textbooks (e.g. Embleton and King, 1975; Judson, Deffeyes, and Hargraves, 1976; Leet, Judson, and Kauffman, 1978; Press and Siever, 1982; Hamblin; 1982).

scholarly journals Formation of levees and en-echelon shear planes during snow avalanche run-out

2012 ◽  
Vol 58 (211) ◽  
pp. 980-992 ◽  
Author(s):  
Perry Bartelt ◽  
James Glover ◽  
Thomas Feistl ◽  
Yves Bühler ◽  
Othmar Buser
Keyword(s):  
Saddle Point ◽  
Mass Flux ◽  
Flow Direction ◽  
Shear Plane ◽  
Flow Parameters ◽  
Mass Fluxes ◽  
Avalanche Flow ◽  
Low Mass ◽  
Steep Slopes ◽  
Shear Planes

AbstractSnow avalanches often form levees and en-echelon shear planes in the run-out zone. We describe the formation of these depositional structures using a simple model that accounts for the role of granular fluctuations in avalanche motion. A mathematical feature of this model is the existence of a bifurcation saddle point, describing how granular fluctuations control the avalanche velocity in the runout zone. The saddle point discriminates between a flowing and stopping regime and defines the physical boundary between the flow and non-flow regions of the avalanche, i.e. the location of shear planes in the avalanche deposits. The formation of a shear plane depends on the interplay between terrain slope and avalanche mass flux, which varies from avalanche head to tail. Levees can form immediately at the avalanche front or, for steep slopes and low mass fluxes, at the avalanche tail. At ravine and gully shoulders the mass flux is restricted, thus initiating levee formation. We find that the levee lines are parallel to the flow direction when the mass flux is constant; en-echelon shear lines occur when the mass flux is decreasing. We test the model using several case studies where we have accurate laser scans of avalanche deposits. Our results suggest that avalanche flow parameters can be determined from simple levee measurements or, conversely, formation of levees and flow fingers can be predicted once the parameters governing the granular fluctuations are known.

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