Redistribution Of Loading Research Articles

Stability enhancement of an axial fan by foam metal casing treatment subjected to circumferential inlet distortion

Circumferential distortion has been a concern since the early development of aeroengines, typically leading to a decrease in stability and efficiency. This paper experimentally investigates the effect of circumferential distortion on a low-speed axial fan and evaluates the potential of foam metal casing treatment (FMCT) to improve the stall margin. Distortions with different intensities were modeled by covering variable areas with wire mesh sectors. Under different distortions, the stall margin with solid casing drops significantly from 38.6% to -7.4%, while FMCT achieves a notable improvement ranging from 14% to 20%. Unsteady measurements were conducted to analyze the pre-stall behavior and the variation in the tip blade loading. The evolution of disturbance energy is presented to discuss the effects of distortion and FMCT on fan stability. It is observed that the proportion of low-frequency disturbance energy amplifies gradually when the rotor is leaving the distorted region. As the distortion angle increases, the maximum amplitude of proportion intensifies. The comparison of the disturbance energy at near stall point between solid casing and FMCT shows that the broadband disturbance energy is suppressed by FMCT. Additionally, the enhancement of stability under inlet distortion is also attributed to the redistribution of tip blade loading.

Stall Inception Analysis on Axial Compressors With Different Rotor Loading Distributions Under Radial Inlet Distortions

Abstract Stability studies were conducted on a single-stage, low-speed compressor with different rotor loading-distribution designs under a uniform inlet, 10% intensity, and 20% intensity total tip pressure distortion inlet conditions via numerical calculations, theoretical model predictions, and experimental methods. The steady numerical performance was in basic agreement with experimentally measured performance. The theoretical prediction model showed an error within 1.5%, which is less than that of the steady numerical calculation. The total tip pressure distortion reduced flow stability. Conversely, the design of moving the rotor loading axially rearward significantly improved the flow stability. The blade loading analysis showed that the radial distortion caused a radial redistribution of rotor loading. The increase in the rotor-tip loading due to tip distortion was the main reason for the reduced flow stability. In contrast, the design of moving the rotor loading axially rearward reduced the rotor-tip leading-edge loading, enhancing the flow stability. Moreover, an analysis of the unsteady flow validated the findings of the blade loading analyses. It was found that the periodic evolution of the tip leakage vortex (TLV) had an adverse effect on flow stability. In addition, the modified rotors could prevent the tip leakage flow (TLF) from spilling from the leading edge and prevent the interaction of different diffusing regions, decreasing the probability of flow separation.

Optimization design method based on parameter reduction and active subspaces: Redistribution of chordwise loading at blade tips in a transonic axial-flow fan

In practical optimization design, an excessive number of design variables have a highly detrimental influence on the efficiency and accuracy of the final design scheme and expose the optimization problem to the curse of dimensionality. Therefore, incorporating only the most essential variables into an optimization design problem facilitates obtaining accurate and cost-efficient solutions. Reported here is an optimization design method based on parameter reduction and active subspaces, and it is used to redistribute the tip load in a transonic fan. Specifically, a coupled design strategy is developed to reduce the number of parameters needed to describe the three-dimensional blade shape, which leads to far fewer design variables being involved in the optimization design. Moreover, active subspaces are used to perform sensitivity analysis and establish low-dimensional surrogate models. After the coupled design, a blade is represented effectively by only three parameters, each of which has a significant influence on the fan performance. Three one-dimensional active subspaces are established for maximum mass flow rate, maximum total pressure ratio, and maximum efficiency, based on which the linear surrogate models are obtained. Next, the chordwise tip blade loading is optimized, after which the rotor efficiency at the design point is increased by 1.1%, while the total pressure ratio remains nearly unchanged. Finally, the flow field is analyzed to understand the mechanism for this performance improvement, and the results show that the optimized blade loading reduces the aerodynamic losses caused by shock-induced flow separation and the interaction between shocks and tip leakage flows.

Biomechanical influence of T1 tilt alteration on adjacent segments after anterior cervical fusion

Background: Anterior cervical fusion (ACF) has become a standard treatment approach to effectively alleviate symptoms in patients with cervical spondylotic myelopathy and radiculopathy. However, alteration of cervical sagittal alignment may accelerate degeneration at segments adjacent to the fusion and thereby compromise the surgical outcome. It remains unknown whether changes in T1 tilt, an important parameter of cervical sagittal alignment, may cause redistribution of biomechanical loading on adjacent segments after ACF surgery. Objective: The objective was to examine the effects of T1 tilt angles on biomechanical responses (i.e.range of motion (ROM) and intradiscal VonMises stress) of the cervical spine before and after ACF. Methods: C2-T1 FE models for pre- and postoperative C4-C6 fusion were constructed on the basis of our previous work. Varying T1 tilts of -10°, -5°, 0°, 5°, and 10° were modeled with an imposed flexion-extension rotation at the T1 inferior endplate for the C2-T1 models. The flexion-extension ROM and intradiscal VonMises stress of functional spinal units were compared between the pre- and postoperative C2-T1 FE models of different T1 tilts. Results: The spinal segments adjacent to ACF demonstrated higher ROM ratios after the operation regardless of T1 tilt. The segmental ROM ratio distribution was influenced as T1 tilt varied and loading conditions, which were more obvious during displacement-control loading of extension. Regardless of T1 tilt, intradiscal VonMises stress was greatly increased at the adjacent segments after the operation. As T1 tilt increased, intradiscal stress at C3-C4 decreased under 30° flexion and increased under 15° extension. The contrary trend was observed at the C6-C7 segment, where the intradiscal stress increased with the increasing T1 tilt under 30° flexion and decreased under 15° extension. Conclusion: T1 tilt change may change biomechanical loadings of cervical spine segments, especially of the adjacent segments after ACF. Extension may be more susceptible to T1 tilt change.

Dynamic pressure analysis of novel interpositional knee spacer implants in 3D-printed human knee models

Alternative treatment methods for knee osteoarthritis (OA) are in demand, to delay the young (< 50 Years) patient’s need for osteotomy or knee replacement. Novel interpositional knee spacers shape based on statistical shape model (SSM) approach and made of polyurethane (PU) were developed to present a minimally invasive method to treat medial OA in the knee. The implant should be supposed to reduce peak strains and pain, restore the stability of the knee, correct the malalignment of a varus knee and improve joint function and gait. Firstly, the spacers were tested in artificial knee models. It is assumed that by application of a spacer, a significant reduction in stress values and a significant increase in the contact area in the medial compartment of the knee will be registered. Biomechanical analysis of the effect of novel interpositional knee spacer implants on pressure distribution in 3D-printed knee model replicas: the primary purpose was the medial joint contact stress-related biomechanics. A secondary purpose was a better understanding of medial/lateral redistribution of joint loading. Six 3D printed knee models were reproduced from cadaveric leg computed tomography. Each of four spacer implants was tested in each knee geometry under realistic arthrokinematic dynamic loading conditions, to examine the pressure distribution in the knee joint. All spacers showed reduced mean stress values by 84–88% and peak stress values by 524–704% in the medial knee joint compartment compared to the non-spacer test condition. The contact area was enlarged by 462–627% as a result of the inserted spacers. Concerning the appreciable contact stress reduction and enlargement of the contact area in the medial knee joint compartment, the premises are in place for testing the implants directly on human knee cadavers to gain further insights into a possible tool for treating medial knee osteoarthritis.

Application of magnetic arc filtration in vacuum arc coating to improve wear resistance of cutting tools

The results of the study of the influence of the method of magnetic arc filtration (MDF) in the application of vacuum ion-plasma coatings based on (Ti, Al)N on the tribological characteristics of cutting tools are presented. It is established that application of MDF at synthesis of coatings on the basis of (Ti, Al)N on cutting tools promotes self-organization (adaptation) of a surface layer with the subsequent provision of unique tribological properties (lubricating effect, hardening effect, etc.) during friction and wear, and also favorable temperature and force conditions at cutting (redistribution of thermal flow and contact loading).

Research of the Modes of Starting and Braking during Work of the Systems of Group Electric Drive of Mine Electric Locomotive with the Different Types of Electric Engines

In the article the results of research of work of mine electric locomotive are driven on condition of stability of the system "A wheel is a rail" on coupling of wheels of electric locomotive with rails. It is marked that work of mine electric locomotive transport is conditioned by the row of specific terms. It is indicated that for realization of the electromechanics systems of mine electric locomotives structures are used with the hauling electric engines of direct and variable current. During working as of mine electric locomotive an important question there is coupling of wheels of electric locomotive with rails. Investigation of worsening of coupling of wheel with a rail is an origin of processes of skidding in the mode of creation of tractive or юза force in the mode braking of electric locomotive, that influence negatively for other knots of hauling electromechanic. In turn stability of the system "A wheel is a rail" depends on the type of hauling electromechanic. At consideration condition of stability of electromechanic on coupling of wheels of electric locomotive with rails important is inflexibility of descriptions of hauling electric motors. What more inflexibility, the higher stability of the system "A wheel is a rail". More hard descriptions can be got in the system of electromechanic with hauling asynchronous engines that give an opportunity to use this fact for realization of proportional distribution of efforts between the wheelpairs of electric locomotive. The systems ticker-coil on speed allow to carry out distribution of hauling and brake efforts that is attached to the wheelpairs of electric locomotive, in accordance with distribution of efforts from these wheelpairs on rails, only after the beginning of processes of skidding or skidding. For the decision of this problem a sufficient condition there is a limit of currents of hauling electric motors on the set level. In this connection possibility of distribution of hauling and brake efforts appears at any moment to time. For the decision of task of rational distribution of efforts of electric locomotive, distribution of forces was analysed between his wheelpairs in the function of total force that pulls an electric locomotive on his coupling. On the basis of analysis an idea was got about the redistribution of loading on the axes of electric locomotive. This distribution is in direct ratio to his total tractive force and coupling height, and in inverse ratio to inflexibility of corps. As a result, in order that propelling and brake forces on the axes of electric locomotive corresponded to distribution of weight on rails on wheelpairs, it is necessary to support identical correlation of weight and efforts on the axes of electric locomotive. The design of transients was conducted in the system of group electric hauling drive of mine electric locomotive in the mode of starting and braking. A design is executed for the engine of direct-current with successive connection of poles and hauling asynchronous engine. The charts of transients in the system of group electric hauling drive of mine electric locomotive in the mode of starting and braking showed absence of processes of skidding and slipping at application of the offered principle for the control system.

Mechanism of Stability Enhancement with Shallow ‎Reversed Slot-Type Casing Treatment in a Transonic ‎Compressor

In this paper, the influence of a shallow reversed slot-type casing treatment on the performance of a tip-critical transonic compressor has been numerically investigated. Firstly, the complex flow fields in the rotor tip region are studied in details. It shows the severe blockage induced by suction surface boundary separation triggers compressor stall at 100% design speed, while the blockage due to tip leakage vortex dominates at 80% design speed. Secondly, the mechanism of stability extension is presented at different rotating speeds. The casing treatment alleviates greatly the tip blockage by manipulating the tip leakage flow, accompanied by the redistribution of aerodynamic loading and mass flux. As a result, the casing treatment is more efficient for the blockage induced by tip leakage vortex (at 80% design speed). Further analysis of the pressure field and passage shock distribution demonstrates that the passage shock intensity and its location will affect the effectiveness of casing treatment. Finally, the instability characteristics of compressor with casing treatment are revealed. The numerical results reflect when the mass flow approaching the instability boundary, the stator passage blockage presumably is dominant for triggering the compressor stall.

Influence of Swirl Clocking on the Performance of Turbine Stage with Three-Dimensional Nozzle Guide Vane

The effect of the swirl clocking on three-dimensional nozzle guide vane (NGV) is investigated using computational fluid dynamics. The research reports the loss characteristics of leaned and swept NGVs and the influence of swirl clocking. The three-dimensional NGVs are built by stacking the same 2D profile along different linear axes, characterized by different angles with respect to the normal or radial direction: ε = −12° ~ +12° for the leaned and γ = −5° ~ +10° for the swept airfoils. A total of 40 models are analyzed to study the effects of lean and sweep on aerodynamic performance. To investigate the influence of swirl clocking, the analysis cases include the center of the swirl that was positioned at the leading edge as well as the middle of the passage. The prediction results show that the relationship of the changes in mass flow rate and throat area are not monotonic. Further observation confirms the redistribution of loading and flow angle under different lean and sweep angles; thus, three-dimensional design is a key influencing factor on aerodynamic performance. In the presence of swirl clocking, NGV performance is changed significantly and the findings offer new insight and opportunities to improve three-dimensional NGV airfoil design.

Exploring the relationship between pain intensity and knee moments in participants with medial knee osteoarthritis: a cross-sectional study

BackgroundHigh biomechanical loading is believed to be a risk factor to pain in people with knee osteoarthritis (OA), but controversial findings have been reported on the relationship between external knee adduction moment (KAM) and pain. A more comprehensive analysis considering other factor such as external knee flexion moment (KFM) could help better reveal this relationship. This study explored the relationship between external knee adduction moment and pain intensity in participants with knee osteoarthritis (OA) using an integrated path analysis model.MethodsThis was a cross-sectional study based on laboratory setting. Forty-seven participants with clinical and radiographic medial knee OA were analyzed for their external knee adduction moment (KAM) and knee flexion moment (KFM) during walking using a motion analysis system. Pain intensity was measured by visual analogue scale (VAS) and the pain subscale of the Knee Injury and Osteoarthritis Outcome Score. Varus/valgus alignment was captured and quantified using a bi-planar X-ray system. Using a path analysis model, the relationships between pain intensity, KAM, KFM, OA radiographic severity, knee varus angle and walking speed were examined.ResultsThe proposed path model met the goodness-of-fit criteria. Based on this model, KAM had a negative effect on VAS pain indirectly through the mediation of KFM. The model indicated KAM and KFM were negatively related to one another; and KFM was positively related to VAS. The KAM index, defined as (KAM/ (KAM + KFM)), was negatively related to VAS.ConclusionsPath analysis enabled the construction of a more integrated pathokinematic framework for people with knee OA. The KAM index which reflected the load sharing on the frontal and sagittal planes also revealed its relationship with pain. Re-distribution of mechanical loading from frontal to sagittal plane might be a strategy for pain avoidance associated with mechanical irritation.

Analytical model of oil pipeline overground transitions, laid in mountain areas

Abnormal climate changes cause adverse physical and geographical processes (erosion of soils, waterlogging, flooding, etc.) over the world. This situation stipulates study on effect of soil foundation malleability on pipeline transition strength because of its important diagnostic value. The article develops an engineering approach for stress–strain state estimation of oil pipeline overground transitions, laid in mountainous areas. A mathematical statement was made and analytical solutions of the boundary-value problem were described, which take into account overland transition contact with soil foundation. In order to carry out the force analysis, a tubular rod simulated the oil pipeline contacting with the soil foundation on the adjacent to the overground transition section according to the Fuss-Winkler hypothesis. The overground transition was schematised with a thin-walled shell at the final stage of the assessment of strength. The maximum axial stresses were determined for overground transition operation, considering transition’s two-dimensional thermoelastic state. The final assessment of the strength was carried out according to the energy criterion. The proposed method for the overground transition simulation makes possible considering the soil foundation property effects on the behavior of the oil pipeline transition and presents the results in the form of concise analytical expressions convenient for engineering practice. The conducted researches showed the effect of significant redistribution of loading in the oil pipeline overground transition caused by changes of soil foundation stiffness. Also, the boundary effect of perturbation of the stressed state in adjacent underground sections was found. It was determined the zone sizes the boundary effect has significant manifestations. The boundary state of the pipeline is most often achieved in its lower fibers at a short distance from the edge of the underground section. The obtained results of researches were tested on real constructions of overground transitions of oil pipeline laid in mountainous areas.

Mechanisms of Sweep on the Performance of Transonic Centrifugal Compressor Impellers

Transonic centrifugal compressors with high performance are required in the oil and gas industries, modern gas turbine engines, and turbochargers. The sweep of the blades is one of the crucial features that have a significant influence on their performance. This paper numerically investigates mechanisms by which sweep affects the performance of a transonic impeller with twin splitters. Sweep is defined as scaling up or down the shroud chord, and the variation range of the sweep angle has been chosen from −25 to +25°. In the current case, results show that the variation of choke mass flow rate, pressure ratio, and efficiency value is around 1%. If the centrifugal compressor has a higher pressure ratio or a higher front loading, the sweep effect on compressor performance will be even stronger. The essential aerodynamic effect of sweep is the spanwise redistribution of the front loading, resulting in effects on the shock structure, the tip leakage vortex, and the flow separation. On the shroud section, forward sweep restricts the front loading, the shock strength, and the tip leakage vortex, which reduces the loss near the casing. On the hub section, aft sweep suppresses the front loading and the flow separation, which reduces the loss near the hub. It is the delicate balance between controlling the loss near the hub and the loss near the casing that determines the optimal sweep angle design.

Rotational gait patterns in children and adolescents following tension band plating of idiopathic genua valga.

Literature suggests that children and adolescents with idiopathic genua valga present with considerable gait deviations in frontal and transverse planes, including altered frontal knee moments, reduced external knee rotation, and increased external hip rotation. This study aimed to evaluate gait parameters in these patients after surgical correction using tension band plating (TBP). We prospectively evaluated 24 consecutive, skeletally immature patients, who received full-length standing radiographs and three-dimensional gait analysis before and after correction, and compared the results observed to a group of 11 typically developing peers. Prior to TBP the cohort showed significantly decreased (worse) internal frontal knee moments compared to the control group. After axis correction the mean and maximum knee moments changed significantly into normalized knee moments (p < 0.0001). In the transverse plane, only the foot progression angle (p = 0.020) changed significantly following intervention. Post-correction knee moments were similar to controls (p = 0.175), but the patient cohort exhibited a significantly decreased knee external rotation (p = 0.004) and increased external hip rotation (p < 0.001) during gait. In addition, the effect of transverse plane changes on knee moments in patients with restored, straight limb axis was calculated. Hence, patients with restored alignment but persistence of decreased external knee rotation demonstrated significantly greater knee moments than those without rotational abnormalities (p = 0.001). This study found that frontal knee moments during gait normalized in children with idiopathic genua valga after surgery. However, decreased external knee rotation and increased external hip rotation during gait persisted in the study cohort. Despite radiological correction, decreased external rotation during gait was associated with increases in medial knee loading. Surgical correction for children with genua valga but normal knee moments may be detrimental, due to redistribution of dynamic knee loading into the opposite joint compartment. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1617-1624, 2017.

Blast Response of Segmented Bored Tunnel using Coupled SPH–FE Method

Underground transport tunnels are vulnerable to blast events. This paper develops and applies a fully coupled technique involving the Smooth Particle Hydrodynamics and Finite Element techniques to investigate the blast response of segmented bored tunnels. Findings indicate that several bolts failed in the longitudinal direction due to redistribution of blast loading to adjacent tunnel rings. The tunnel segments respond as arch mechanisms in the transverse direction and suffered damage mainly due to high bending stresses. The novel information from the present study will enable safer designs of buried tunnels and provide a benchmark reference for future developments in this area.

Improved contact load-bearing capacity of ultra-fine grained titanium: Multilayering and grading

The contact load-bearing response and surface damage resistance of multilayered hierarchical structured (MHSed) titanium were determined and compared to monolithic nanostructured titanium. The MHS structure was formed by combining cryorolling with a subsequent Surface Mechanical Attrition Treatment (SMAT) producing a surface structure consisted of an outer amorphous layer containing nanocrystals, an inner nanostructured layer and finally an ultra-fine grained core. The combination of a hard outer layer, a gradual transition layer and a compliant core results in reduced indentation depth, but a deeper and more diffuse sub-surface plastic deformation zone, compared to the monolithic nanostructured Ti. The redistribution of surface loading between the successive layers in the MHS Ti resulted in the suppression of cracking, whereas the monolithic nanograined (NG) Ti exhibited sub-surface cracks at the boundary of the plastic strain field. Finite element models with discrete layers and mechanically graded layers representing the MHS system confirmed the absence of cracking and revealed a 38% decrease in shear stress in the sub-surface plastic strain field, compared to the monolithic NG Ti. Further, the mechanical gradation achieves a more gradual stress distribution which mitigates the interface failure and increases the interfacial toughness, thus providing strong resistance to loading damage.

Rail squats: progress in understanding the Australian experience

Rail squats or studs, being a sub-surface crack in a track below a depression of the rail surface, have been studied in the Australian CRC for Rail Innovation project R3.105, from a number of perspectives. Examination of squats on track by the Rail Corporation of NSW has revealed statistics about their distribution. Examination with optical and scanning electron microscopy at the University of Queensland has shown the frequent presence of a brittle white etching layer (WEL) on the rail surface. This has led to successful adaptation of eddy currents to detect WEL rather than cracks. Tests at the University of Queensland have investigated whether the WEL can form below the normal 720℃ needed to form austenite. Examination of crack surfaces shows beach marks indicative of growth in modes II and III. Neutron diffraction testing of Australian rail has shown residual stresses in a railhead with a WEL, similar to those reported elsewhere, but with a broad surface layer in compression, not a narrow running band. Elasto-plastic finite element simulation has shown residual compression transforms into residual shear at a crack tip, which increases that due to plastic deformation from successive wheel passages, tending to encourage the crack to continue in a direction of sub-surface growth. The rate of growth of squats measured on-track in Sydney shows crack growth that corresponds to a power law with a low exponent, implying that the stress intensity at the crack tip is not a strong function of crack length. This is partly due to the localised nature of contact stresses, which allows the crack to grow beyond the region loaded. However, accounting for this effect leads to the prediction of a smaller reduction in growth rate than that observed. It is likely the low exponent reflects a smaller effect of water on crack growth, as the crack enlarges. There is also a redistribution of contact loading that occurs as a crack grows.

Measuring tidal displacement using GPS

GPS is making possible high‐precision, high‐resolution measurements of tidal displacement that could not be achieved with other methods. Earth's surface deforms due to both body tides—the deformation of the solid Earth due to the pull of the Sun and the Moon—and ocean tides—the redistribution of water mass loading over Earth's surface. Body tides and ocean tides both have components that vary on semidiurnal, diurnal, and longer periods.

Advanced Nonaxisymmetric Endwall Contouring for Axial Compressors by Generating an Aerodynamic Separator—Part II: Experimental and Numerical Cascade Investigation

Modern methods for axial compressor design are capable of shaping the blade surfaces in a three-dimensional way. Linking these methods with automated optimization techniques provides a major benefit to the design process. The application of nonaxisymmetric contoured endwalls is considered to be very successful in turbine rotors and vanes. Concerning axial compressors, nonaxisymmetric endwalls are still a field of research. This two-part paper presents the recent development of a novel endwall design. A vortex created by a nonaxisymmetric endwall groove acts as an aerodynamic separator, preventing the passage vortex from interacting with the suction side boundary layer. This major impact on the secondary flow results in a significant loss reduction by means of load redistribution, reduction in recirculation areas, and suppressed corner separation. Part I of this paper deals with the endwall design and its compressor application. The resulting flow phenomena and physics are described and analyzed in detail. The second paper presents the detailed experimental and numerical investigation of the developed endwall groove. The measurements carried out at the transonic cascade wind tunnel of DLR in Cologne, demonstrated a considerable influence on the cascade performance. A loss reduction and redistribution of the cascade loading were achieved at the aerodynamic design point, as well as near the stall condition of the cascade. This behavior is well predicted by the numerical simulation. The combined analysis of experimental and numerical flow patterns allows a detailed interpretation and description of the resulting flow phenomena. In this context, high fidelity 3D-Reynolds-averaged Navier–Stokes flow simulations are required to analyze the complex blade and endwall boundary layer interaction.

Earthquake Shear Load in Load-Bearing Masonry Buildings

Load-bearing masonry buildings are composed of concrete slabs and supporting masonry walls, and in Australia usually incorporate slip joints in the interfaces between walls and slabs for serviceability reasons. The apparent conflicting requirements of the slip joints, to slip under long-term loads and to transmit short-term loading from wind and earthquake actions, together with the lack of attention to the design of slip joints, make slip in the joints likely to occur when the building is subjected to a lateral loading. Joint slip leads to a redistribution of loading in the building wall system, resulting in wall shear loads different from that determined using the current standard elastic design procedures. Redistribution of loading may be also caused by softening of the masonry. This paper has assessed the realistic response of various load-bearing masonry buildings, including the potential for slip in the joints and softening of the masonry, and evaluated the level of wall shear load deviations resulting from the application of current design procedures. Analyses of the buildings, using non-linear static and dynamic finite element models, have indicated that joint slip may occur in buildings subjected to earthquake loading. The application of current elastic design procedures, which do not account for loading redistribution, resulted in major wall shear load deviations, such as overestimations of up to +75% and underestimations of up to-62%. It was therefore concluded that improvements in the current design procedures are required for a more accurate evaluation of wall shear loads in load-bearing masonry buildings subjected to the lateral loading.

Elevated shear zone loading rate during an earthquake cluster in eastern California

Research Article| June 01, 2008 Elevated shear zone loading rate during an earthquake cluster in eastern California Michael Oskin; Michael Oskin * 1Department of Geological Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA *E-mail: oskin@email.unc.edu. Search for other works by this author on: GSW Google Scholar Lesley Perg; Lesley Perg 2Department of Geology and Geophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA Search for other works by this author on: GSW Google Scholar Eitan Shelef; Eitan Shelef 3Department of Geological Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA Search for other works by this author on: GSW Google Scholar Michael Strane; Michael Strane 3Department of Geological Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA Search for other works by this author on: GSW Google Scholar Emily Gurney; Emily Gurney 3Department of Geological Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA Search for other works by this author on: GSW Google Scholar Brad Singer; Brad Singer 4Department of Geology and Geophysics, University of Wisconsin, Madison, Wisconsin 53706, USA Search for other works by this author on: GSW Google Scholar Xifan Zhang Xifan Zhang 4Department of Geology and Geophysics, University of Wisconsin, Madison, Wisconsin 53706, USA Search for other works by this author on: GSW Google Scholar Geology (2008) 36 (6): 507–510. https://doi.org/10.1130/G24814A.1 Article history received: 25 Jan 2008 rev-recd: 27 Feb 2008 accepted: 03 Mar 2008 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Michael Oskin, Lesley Perg, Eitan Shelef, Michael Strane, Emily Gurney, Brad Singer, Xifan Zhang; Elevated shear zone loading rate during an earthquake cluster in eastern California. Geology 2008;; 36 (6): 507–510. doi: https://doi.org/10.1130/G24814A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract We compare geodetic velocity to geologic fault slip rates to show that tectonic loading was doubled across the eastern California shear zone (ECSZ) during a cluster of major earthquake activity. New slip rates are presented for six dextral faults that compose the ECSZ in the central Mojave Desert. These rates were determined from displaced alluvial fans dated with cosmogenic 10Be and from a displaced lava flow dated with 40Ar/39Ar. We find that the sum geologic Mojave ECSZ slip rate, ≤6.2 ± 1.9 mm/yr, is only half the present-day geodetically measured velocity of 12 ± 2 mm/yr. These rates account for cumulative fault slip and geodetic observations that span the 60-km-wide shear zone; therefore this difference cannot be attributed to postseismic relaxation. Redistribution of tectonic loading over the earthquake cycle at a regional scale suggests that earthquake clustering may be enhanced via feedback with weakening of ductile shear zones. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.