Aerospace. Constant displacement hydraulic motors. General specifications for 35000 kPa systems

Geosynthetic-reinforced soil structures have been used extensively in recent decades due to their significant advantages over more conventional earth retaining structures, including the cost-effectiveness, reduced construction time, and possibility of using locally-available lower quality soils and/or waste materials, such as recycled construction and demolition (C&D) wastes. The time-dependent shear behaviour at the interfaces between the geosynthetic and the backfill is an important factor affecting the overall long-term performance of such structures, and thereby should be properly understood. In this study, an innovative multistage direct shear test procedure is introduced to characterise the time-dependent response of the interface between a high-strength geotextile and a recycled C&D material. After a prescribed shear displacement is reached, the shear box is kept stationary for a specific period of time, after which the test proceeds again, at a constant displacement rate, until the peak and large-displacement shear strengths are mobilised. The shear stress-shear displacement curves from the proposed multistage tests exhibited a progressive decrease in shear stress with time (stress relaxation) during the period in which the shear box was restrained from any movement, which was more pronounced under lower normal stress values. Regardless of the prior interface shear displacement and duration of the stress relaxation stage, the peak and residual shear strength parameters of the C&D material-geotextile interface remained similar to those obtained from the conventional (benchmark) tests carried out under constant displacement rate.

Download Full-text

Hydraulic motors for new offshore booms

Marine Pollution Bulletin ◽

10.1016/0025-326x(90)90657-t ◽

1990 ◽

Vol 21 (8) ◽

pp. 406-407

Keyword(s):

Hydraulic Motors

Download Full-text

Design and Operational Experience of the SWATH Ship Navatek I

Marine Technology and SNAME News ◽

10.5957/mt1.1993.30.3.153 ◽

1993 ◽

Vol 30 (03) ◽

pp. 153-171

Author(s):

Ludwig H. Seidl ◽

William F. Clifford ◽

James P. Cummings

Keyword(s):

Structural Analysis ◽

Parametric Study ◽

Historical Development ◽

Ship Motion ◽

Actual Data ◽

Operational Experience ◽

General Design ◽

Design Considerations ◽

Constant Displacement ◽

Hull Forms

A presentation is attempted linking the historical development, general design considerations for Small Waterplane Area, Twin-Hull (SWATH) hull shapes, the design of a particular SWATH, the Navatek/, and her operational experience. The "carrier vessel" concept on which the Navatek I is based is introduced. Principal dimensions and general arrangements are shown. A parametric study of twin-strut SWATH hull forms for a hull of constant displacement is presented in some detail. Stability and ship motion are discussed and actual data for the Navatek I presented. The overall structural analysis is briefly presented, including the method of analysis for the Navatek I. The SWATH captain's operational experience with the Navatek I during her extensive journeys is related to quite some extent.

Download Full-text

Deformation of Porous, Nanostructured Silver at Room Temperature and 150 °C

MRS Proceedings ◽

10.1557/opl.2013.963 ◽

2013 ◽

Vol 1513 ◽

Author(s):

Guillaume Noiseau ◽

Michael F. Becker ◽

John W. Keto ◽

Desiderio Kovar

Keyword(s):

Room Temperature ◽

Local Strain ◽

Direct Write ◽

Compression Tests ◽

Sufficient Energy ◽

Starting Point ◽

Mean Size ◽

Constant Displacement ◽

Patterned Films ◽

Porous Silver

ABSTRACTPorous, nanostructured silver samples were produced using a direct-write method where a nanoparticle aerosol consisting of particles with a mean size of approximately 5 nm were accelerated to speeds of approximately 1000 m/sec and impacted onto a translating substrate [1]. The impacting particles have sufficient energy to stick to the substrate, allowing patterned thick films to be directly written from the aerosol without a mask. Unlike other low temperature processing routes for achieving patterned films, no organics are added that can interfere with postdeposition processing. Typical films are 5- 100 μm thick, up to several centimeters long, and have an as-deposited relative densities as high as 70% of bulk Ag. Compression tests were carried out in steps at room temperature and at 150°C under constant displacement rates. Local strain and densification were measured by optical profilometry between each compression step. The results can be used as a starting point to better understand the mechanisms that govern plasticity, creep, and sintering in nanostructured, porous silver at low processing temperatures.

Download Full-text

Spherical indentation load-relaxation of soft biological tissues

Journal of Materials Research ◽

10.1557/jmr.2006.0243 ◽

2006 ◽

Vol 21 (8) ◽

pp. 2003-2010 ◽

Cited By ~ 121

Author(s):

Jason M. Mattice ◽

Anthony G. Lau ◽

Michelle L. Oyen ◽

Richard W. Kent

Keyword(s):

Costal Cartilage ◽

Kidney Tissue ◽

Biological Tissues ◽

Indentation Load ◽

Spherical Indentation ◽

Load Relaxation ◽

Soft Biological Tissues ◽

Long Time ◽

Constant Displacement ◽

Soft Biological Materials

Elastic-viscoelastic correspondence was used to generate displacement–time solutions for spherical indentation testing of soft biological materials with time-dependent mechanical behavior. Boltzmann hereditary integral operators were used to determine solutions for indentation load-relaxation following a constant displacement rate ramp. A “ramp correction factor” approach was used for routine analysis of experimental load-relaxation data. Experimental load-relaxation tests were performed on rubber, as well as kidney tissue and costal cartilage, two hydrated soft biological tissues with vastly different mechanical responses. The experimental data were fit to the spherical indentation ramp-relaxation solutions to obtain values of short- and long-time shear modulus and of material time constants. The method is used to demonstrate linearly viscoelastic responses in rubber, level-independent indentation results for costal cartilage, and age-independent indentation results for kidney parenchymal tissue.

Download Full-text