Effect of strain rate on the adhesive bond shearing resistance of stiff clay

2021 ◽  
Vol 27 ◽  
pp. 100479
Author(s):  
Jian Han ◽  
Zhen-Yu Yin ◽  
Christophe Dano ◽  
Pierre-Yves Hicher
Keyword(s):  
Strain Rate ◽  
Adhesive Bond ◽  
Shearing Resistance ◽  
Stiff Clay

The Performance of Dynamically Embedded Anchors in Calcareous Silt

2013 ◽  
Author(s):  
Christophe Gaudin ◽  
Conleth D. O’Loughlin ◽  
Muhammad S. Hossain ◽  
Evan H. Zimmerman
Keyword(s):  
Strain Rate ◽  
Penetration Depth ◽  
Diving Behaviour ◽  
Model Parameters ◽  
Geotechnical Centrifuge ◽  
Testing Programme ◽  
Experimental Programme ◽  
Shearing Resistance ◽  
Anchor Length ◽  
New Type

The Omni-Max anchor is a new type of dynamically installed anchor featuring a mooring arm located close to the anchor tip that is free to rotate about the anchor length. An experimental programme has been undertaken on a geotechnical centrifuge to assess the anchor performance in calcareous silt. The testing programme includes (i) anchor drops and measurement of the penetration depth, and (ii) anchor pull and assessment of the anchor trajectory. An anchor embedment model based on strain rate enhanced shearing resistance is capable of satisfactorily predicting anchor embedment using model parameters that are similar to those used for clay. The diving behaviour of the anchor, post keying, is demonstrated, provided that the initial embedment after impact is deep enough to prevent a shallow mechanism to develop during anchor keying.

scholarly journals Strain Rate Dependent Behaviour of a Natural Stiff Clay

1999 ◽  
Vol 39 (2) ◽  
pp. 69-82 ◽  
Author(s):  
Anna d’Onofrio ◽  
Francesco Silvestri ◽  
Filippo Vinale
Keyword(s):  
Strain Rate ◽  
Rate Dependent ◽  
Stiff Clay ◽  
Dependent Behaviour

Assessing the penetration resistance acting on a dynamically installed anchor in normally consolidated and overconsolidated clay

2017 ◽  
Vol 54 (1) ◽  
pp. 1-17 ◽  
Author(s):  
C. O’Beirne ◽  
C.D. O’Loughlin ◽  
C. Gaudin
Keyword(s):  
Strain Rate ◽  
Frictional Resistance ◽  
Embedment Depth ◽  
Rate Dependency ◽  
Mems Accelerometer ◽  
Rate Dependent ◽  
Centrifuge Tests ◽  
Shearing Resistance ◽  
Soil Interface ◽  
Overconsolidated Clay

Predicting the final embedment depth of a dynamically installed anchor is a key prerequisite for reliable calculation of anchor capacity. This paper investigates the embedment characteristics of dynamically installed anchors in normally consolidated and overconsolidated clay through a series of centrifuge tests involving a model anchor instrumented with a microelectric mechanical system (MEMS) accelerometer, enabling the full motion response of the anchor to be established. The data are used to assess the performance of an anchor embedment model based on strain-rate-dependent shearing resistance and fluid mechanics drag resistance. Predictions of a database of over 100 anchor installations — formed from this study and the literature — result in calculated anchor embedment depths that are within ±15% of the measurements. An interesting aspect, consistent across the entire database, relates to the strain rate dependence on frictional resistance relative to bearing resistance. The predictions reveal that strain rate dependency may indeed be higher for frictional resistance, although only if a soil strength lower than the fully remoulded strength is considered as the reference strength, which suggests that water may be entrained along a boundary layer at the anchor–soil interface during installation.

Effect of Strain Rate on Mechanical Properties of Two-Component Epoxy Adhesive Bond

2014 ◽  
Vol 1059 ◽  
pp. 91-97
Author(s):  
Jan Cidlina ◽  
Jozef Žarnovský ◽  
Miroslav Müller
Keyword(s):  
Strain Rate ◽  
Failure Time ◽  
Adhesive Bond ◽  
Epoxy Adhesive ◽  
Time To Failure ◽  
Bonded Joints ◽  
Affecting Factors ◽  
Epoxy Adhesives ◽  
Adhesive Bonded Joints ◽  
Basic Standard

In practice, adhesive bonded joints are loaded by different intensity and rate. In the case where bond bearing capacity is exceeded, failure occurs. One of the affecting factors is strain rate. In the laboratory tests, ČSN EN 1465 is used as a basic standard, specifying the rate of deformation in the interval of 65±20 seconds. The goal of this research is to describe the behaviour of two-part epoxy adhesives at different strain rate of bonded joints. Experiments evaluated the changes of bond strength, deformation and time to failure. Time to failure is particularly significant because of the potential consequences of fast structural joint violation.

Centrifuge Tests on Dynamically Installed Anchors

2009 ◽  
Author(s):  
Conleth D. O’Loughlin ◽  
Mark D. Richardson ◽  
Mark F. Randolph
Keyword(s):  
Strain Rate ◽  
Impact Velocity ◽  
Free Fall ◽  
Equivalent Strain ◽  
Strain Rates ◽  
Rate Dependent ◽  
Centrifuge Tests ◽  
Shearing Resistance ◽  
Anchor Length ◽  
Target Depth

Dynamically installed anchors are torpedo shaped and are designed so that after release from a designated height above the seafloor will penetrate to a target depth in the seabed by the kinetic energy obtained through free-fall and through the self-weight of the anchor. This paper presents results from an extensive series of centrifuge tests undertaken to both inform expected anchor penetrations in normally consolidated clay and form the basis for calibrating an analytical anchor embedment model. The database indicates that for anchors with no flukes, expected anchor tip embedment depths are 2 to 3 times the anchor length for impact velocities approaching 30 m/s, with a dependence on both impact velocity and to a greater extent anchor mass. The centrifuge data were used to calibrate an analytical embedment model, based on strain rate dependent shearing resistance and fluid mechanics drag resistance. Back-figured strain rate parameters increase with increasing impact velocity and are in the range 0.2–0.5 (logarithmic function) and 0.06–0.12 (power function). As the strain rates in the centrifuge tests are approximately 200 times equivalent strain rates in the field, the lower bound strain rate parameters are considered more appropriate for field conditions.

Dislocation Substructures Produced During Tensile, Creep, and Fatigue Deformation of Ti3Al at 700°C

1977 ◽  
Vol 35 ◽  
pp. 272-273
Author(s):  
S. M. L. Sastry
Keyword(s):  
Intermetallic Compound ◽  
Strain Rate ◽  
Tensile Creep ◽  
Slip Systems ◽  
Slip Vector ◽  
Superlattice Structure ◽  
Slip Activity ◽  
Dislocation Arrangement ◽  
Ordered Intermetallic ◽  
Tangled Dislocation

Ti3Al is an ordered intermetallic compound having the DO19-type superlattice structure. The compound exhibits very limited ductility in tension below 700°C because of a pronounced planarity of slip and the absence of a sufficient number of independent slip systems. Significant differences in slip behavior in the compound as a result of differences in strain rate and mode of deformation are reported here.Figure 1 is a comparison of dislocation substructures in polycrystalline Ti3Al specimens deformed in tension, creep, and fatigue. Slip activity on both the basal and prism planes is observed for each mode of deformation. The dominant slip vector in unidirectional deformation is the a-type (b) = <1120>) (Fig. la). The dislocations are straight, occur for the most part in a screw orientation, and are arranged in planar bands. In contrast, the dislocation distribution in specimens crept at 700°C (Fig. lb) is characterized by a much reduced planarity of slip, a tangled dislocation arrangement instead of planar bands, and an increased incidence of nonbasal slip vectors.

Quantitative analysis of in situ straining experiments in the case of strong frictional forces

1978 ◽  
Vol 36 (1) ◽  
pp. 570-571
Author(s):  
F. Louchet ◽  
L.P. Kubin
Keyword(s):  
Strain Rate ◽  
Radiation Effects ◽  
Dislocation Line ◽  
Critical Length ◽  
Local Strain ◽  
Local Flow ◽  
Double Kink ◽  
Dislocation Densities ◽  
Frictional Forces ◽  
Local Strain Rate

Investigation of frictional forces -Experimental techniques and working conditions in the high voltage electron microscope have already been described (1). Care has been taken in order to minimize both surface and radiation effects under deformation conditions.Dislocation densities and velocities are measured on the records of the deformation. It can be noticed that mobile dislocation densities can be far below the total dislocation density in the operative system. The local strain-rate can be deduced from these measurements. The local flow stresses are deduced from the curvature radii of the dislocations when the local strain-rate reaches the values of ∿ 10-4 s-1.For a straight screw segment of length L moving by double-kink nucleation between two pinning points, the velocity is :where ΔG(τ) is the activation energy and lc the critical length for double-kink nucleation. The term L/lc takes into account the number of simultaneous attempts for double-kink nucleation on the dislocation line.

Observations of dislocation interactions with recrystallized grain boundaries

1988 ◽  
Vol 46 ◽  
pp. 628-629
Author(s):  
C. W. Price
Keyword(s):  
Dislocation Density ◽  
Grain Boundary ◽  
Strain Rate ◽  
Grain Boundaries ◽  
Dislocation Structure ◽  
Hot Deformation ◽  
Static Recrystallization ◽  
High Dislocation Density ◽  
High Angle ◽  
Dislocation Interactions

Little evidence exists on the interaction of individual dislocations with recrystallized grain boundaries, primarily because of the severely overlapping contrast of the high dislocation density usually present during recrystallization. Interesting evidence of such interaction, Fig. 1, was discovered during examination of some old work on the hot deformation of Al-4.64 Cu. The specimen was deformed in a programmable thermomechanical instrument at 527 C and a strain rate of 25 cm/cm/s to a strain of 0.7. Static recrystallization occurred during a post anneal of 23 s also at 527 C. The figure shows evidence of dissociation of a subboundary at an intersection with a recrystallized high-angle grain boundary. At least one set of dislocations appears to be out of contrast in Fig. 1, and a grainboundary precipitate also is visible. Unfortunately, only subgrain sizes were of interest at the time the micrograph was recorded, and no attempt was made to analyze the dislocation structure.

Observation of dislocations in dynamically loaded Cu-SiO2

1986 ◽  
Vol 44 ◽  
pp. 424-425
Author(s):  
D. S. Pritchard
Keyword(s):  
Electron Microscope ◽  
Strain Rate ◽  
Single Crystal ◽  
Transmission Electron Microscope ◽  
Volume Fraction ◽  
Screw Dislocations ◽  
Spherical Inclusions ◽  
Transmission Electron ◽  
Crystal Dispersion ◽  
Strain Rate Loading

The effect of varying the strain rate loading conditions in compression on a copper single crystal dispersion-hardened with SiO2 particles has been examined. These particles appear as small spherical inclusions in the copper lattice and have a volume fraction of 0.6%. The structure of representative crystals was examined prior to any testing on a transmission electron microscope (TEM) to determine the nature of the dislocations initially present in the tested crystals. Only a few scattered edge and screw dislocations were viewed in those specimens.

The effects of strain and strain rate on residual microstructures in copper

1986 ◽  
Vol 44 ◽  
pp. 420-421
Author(s):  
M. F. Stevens ◽  
P. S. Follansbee
Keyword(s):  
Strain Rate ◽  
Applied Stress ◽  
Threshold Stress ◽  
Rate Sensitivity ◽  
Viscous Drag ◽  
Strain Rates ◽  
Strain And Strain Rate ◽  
Threshold Strength ◽  
Mechanism Transition ◽  
Intrinsic Strength

The strain rate sensitivity of a variety of materials is known to increase rapidly at strain rates exceeding ∼103 sec-1. This transition has most often in the past been attributed to a transition from thermally activated guide to viscous drag control. An important condition for imposition of dislocation drag effects is that the applied stress, σ, must be on the order of or greater than the threshold stress, which is the flow stress at OK. From Fig. 1, it can be seen for OFE Cu that the ratio of the applied stress to threshold stress remains constant even at strain rates as high as 104 sec-1 suggesting that there is not a mechanism transition but that the intrinsic strength is increasing, since the threshold strength is a mechanical measure of intrinsic strength. These measurements were made at constant strain levels of 0.2, wnich is not a guarantee of constant microstructure. The increase in threshold stress at higher strain rates is a strong indication that the microstructural evolution is a function of strain rate and that the dependence becomes stronger at high strain rates.

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