Impact compression behaviors of high-capacity long piles

2010 ◽  
Vol 47 (12) ◽  
pp. 1335-1350 ◽  
Author(s):  
Arthur K.O. So ◽  
Charles W.W. Ng
Keyword(s):  
Energy Transfer ◽  
Impact Velocity ◽  
Stress Wave ◽  
Impact Energy ◽  
High Capacity ◽  
Measured Data ◽  
Impact Compression ◽  
Impact Forces ◽  
The Impact ◽  
Pile Length

The Hiley formula underestimates driving resistance of long piles. Methods using affected pile length have been suggested, but have been found to be inapplicable for high-capacity piles. The impact compression behaviors of about 4700 high-capacity H-piles that were 14–80 m long at final set were studied. Measured data revealed that maximum impact forces are very scattered, but their means are independent of the hammer type, ram weight, ram drop, impact velocity, and pile length. Maximum impact compression of pile and affected pile length exist in both long and short piles. The affected pile length in turn is significant to the blow efficiency, hammer constant, and energy transfer ratio. This length is governed by the impact momentum and impact energy, and can be estimated by an energy-based equation. If the affected pile length determined by this equation is substituted into the Hiley formula to back-analyze the driving resistance, predictability of the driving formula can be improved by about 8%. This improvement is significant enough to reduce the number of hammer blows required at very hard driving conditions and reduce pile damage. Furthermore, this proposed equation is simple to use in the field and is more economical compared with stress-wave monitoring techniques.

scholarly journals Lifting a sessile oil drop from a superamphiphobic surface with an impacting one

2020 ◽  
Vol 6 (34) ◽  
pp. eaba4330
Author(s):  
Olinka Ramírez-Soto ◽  
Vatsal Sanjay ◽  
Detlef Lohse ◽  
Jonathan T. Pham ◽  
Doris Vollmer
Keyword(s):  
Surface Tension ◽  
Energy Transfer ◽  
Impact Velocity ◽  
Sessile Drop ◽  
Cloud Formation ◽  
Impact Dynamics ◽  
Combustion Engines ◽  
Intrinsic Properties ◽  
Natural Processes ◽  
The Impact

Colliding drops are encountered in everyday technologies and natural processes, from combustion engines and commodity sprays to raindrops and cloud formation. The outcome of a collision depends on many factors, including the impact velocity and the degree of alignment, and intrinsic properties like surface tension. Yet, little is known on binary impact dynamics of low-surface-tension drops on a low-wetting surface. We investigate the dynamics of an oil drop impacting an identical sessile drop sitting on a superamphiphobic surface. We observe five rebound scenarios, four of which do not involve coalescence. We describe two previously unexplored cases for sessile drop liftoff, resulting from drop-on-drop impact. Numerical simulations quantitatively reproduce the rebound scenarios and enable quantification of velocity profiles, energy transfer, and viscous dissipation. Our results illustrate how varying the offset from head-on alignment and the impact velocity results in controllable rebound dynamics for oil drop collisions on superamphiphobic surfaces.

scholarly journals Experimental and Numerical Investigation of Hard Rock Breakage by Indenter Impact

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Hongxiang Jiang ◽  
Zhiyuan Cai ◽  
Ouguo Wang ◽  
Deguang Meng
Keyword(s):  
Energy Consumption ◽  
Impact Velocity ◽  
Impact Energy ◽  
Specific Energy ◽  
Specific Energy Consumption ◽  
Decisive Role ◽  
Rock Breakage ◽  
Radial Cracks ◽  
The Impact ◽  
Indenter Shape

To investigate the effect of indenter shape, impact energy, and impact velocity on the rock breakage performance, a test device for rock fragmentation by indenter impact was developed to obtain the rock breakage volume, depth, and area under different impact conditions. By comparing the rock breakage volume, depth, area, and specific energy consumption, the results show that indenter shape has a greater influence on the rock breakage performance than that of the impact velocity with the same impact energy, and impact energy plays a decisive role in rock breakage performance with an identical indenter shape and impact velocity. For the lowest to highest specific energy consumption, the order of indenter shape is cusp-conical, warhead, hemispherical, spherical-arc, and flat-top under the same impact energy and velocity, but the cusp-conical indenter is damaged after several impacts. The rock breakage volume, depth, and area all increase with the increase in impact energy, but the effect of the impact velocity could be ignored under the same impact energy. In addition, the rock breakage features of the numerical simulation and experiments are similar, which show that the crushing zone close to the indenter impact point is mainly caused by the high compressive stress, and then radial cracks are caused by the accumulative energy release. The findings of this study will contribute to progress in the performance and efficiency for percussive rock drilling.

Control of Large-Scale Impacts by Designed Structural Damping

2005 ◽  
Author(s):  
Jan Wigaard ◽  
Christopher Hoen ◽  
Sverre Haver
Keyword(s):  
Impact Energy ◽  
Large Scale ◽  
Permanent Deformation ◽  
Energy Levels ◽  
Attractive Alternative ◽  
Safety Level ◽  
Shock Absorbers ◽  
Impact Forces ◽  
Multi Body ◽  
The Impact

Modification of deep-water floaters often involves module installation using a floating crane vessel. The impact forces caused by relative motions between the floating vessels represent a major challenge during set down on the floater deck due to the large inherent variability of these forces. Traditionally the difficulties in predicting impact forces during module installation have been overcome by the use of experienced based rules of thumb rather than accurate simulations and calculations. One has to some degree relied on the indeed present but un-quantifiable effect of human intelligence of the operation supervisor. Traditionally the impact forces are taken either by elastic deformation of the module itself and/or the installation guides or by permanent deformation of intermediate structural elements through e.g. plastic yielding of ductile metal members or crushing of wood members. Designing the module and the guides to be able to take the entire probable range of impact forces is difficult due to the inherent contradiction between wanted flexibility and required strength. The large uncertainties of the impact energy imply that it is difficult to design these intermediate elements to cover all possible impact energy levels. Furthermore, these elements cannot be applied in cases where repeated impacts may occur. An attractive alternative to the traditional solutions is application of industrial shock absorbers. The performance of these is predictable and they can be designed to cover the estimated range of impact energy. This paper will present a more precise and consistent design and analyses methodology that gives a more accurate measure on the reliability of the operation in accordance with code requirements. The paper will show application of industrial shock absorbers as an alternative to traditional solutions for impact handling during offshore module installation to floating vessels, illustrated with experience gained by the installation of two modules on the Visund Semi. Results from multi-body simulations and model tests comparing traditional methods with the proposed solution will be given. The significant benefits obtained with respect to increased operational performance, reduced acceleration loads on the installed equipment, the increased predictability of the operation, and the consistent safety level in accordance with code requirements, will be highlighted. The possibility to apply designed damping for other offshore applications like dropped object protection etc, is also discussed.

3D printed geometrically tessellated sheets with origami-inspired patterns

2021 ◽  
pp. 0021955X2110618
Author(s):  
Anastasia L. Wickeler ◽  
Hani E. Naguib
Keyword(s):  
Impact Energy ◽  
Single Layer ◽  
Impact Testing ◽  
Impact Loads ◽  
Geometrical Complexity ◽  
Impact Forces ◽  
3D Printed ◽  
The Impact ◽  
Multiple Configurations ◽  
Absorb Impact Energy

This study demonstrates that the impact energy absorption capabilities of flexible sheets can be significantly enhanced by implementing tessellated designs into their structure. Configurations of three tessellated geometries were tested; they included a triangular-based, a rectangular-based, and a novel square-based pattern. Due to their geometrical complexity, multiple configurations of these tessellations were printed from a rubber-like material using an inkjet printer with two different thicknesses (2 and 4 mm), and their ability to absorb impact energy was compared to an unpatterned inkjet-printed sheet. In addition, the effect of multi-sheets stacking was also tested. Due to the tailored structure, the impact testing showed that the single-layer sheets were more effective at absorbing impact loads, and experience less deformation, than their two-layer counterparts. The 4 mm thick tessellated patterns were most effective at absorbing impact loads; all three thick patterns measured about 40% lower impact forces transferred to the base of the samples compared to the unpatterned counterparts.

Research on the Mechanical Properties and Energy Consumption Transfer Law of Cement Tailings Backfill Under Impact Load

2021 ◽  
Vol 13 (5) ◽  
pp. 889-898
Author(s):  
Yong-Ye Mu ◽  
Xiang-Long Li ◽  
Jian-Guo Wang ◽  
Zhi-Gao Leng
Keyword(s):  
Mechanical Properties ◽  
Energy Transfer ◽  
Impact Load ◽  
Peak Stress ◽  
Peak Strain ◽  
Impact Compression ◽  
Average Strain Rate ◽  
Failure Morphology ◽  
The Stability ◽  
The Impact

The cemented tailings backfill (CTB), which plays a significant role in the stability of mine structure, is made of cement, tailings, and water in a certain proportion. When blasting and excavating an underground mine, the CTB will be disturbed by blasting. The impact load of blasting has an impact on the stability of the CTB, which is directly related to the safety of mine construction. The mechanical behaviour of CTB is generally affected by the cement-tailings ratio (C/T) and average strain rate (ASR). Therefore, a series of impact experiments were carried out on three CTB specimens with different C/T using a SHPB. Combined with the experimental results, this account reports studies on the effects of C/T and ASR on the mechanical properties of CTB, and on the energy transfer laws of CTB during impact compression. The research results show that when the ASR is less than 70 s−1, the peak stress and the peak strain have the same trend, and both of them continue to increase with the increase of ASR.When the ASR exceeds 70 s−1, as the ASR increases, the peak stress continues to increase, but the peak strain decreases gradually. Afterwards, the law of energy transfer of the CTB specimen was analyzed. It was found that as the incident energy increased, the energy reflection ratio of the CTB increased. Both the energy transmitted ratio and the energy dissipation ratio decreased. The volumetric energy showed a sharp increase first and then a trend Because of the slowly increasing trend. Finally, according to the failure morphology of the CTB, it is found that the ASR and the C/T together affect the failure of the CTB. The failure model of the CTB is mainly split failure and crush failure.

scholarly journals Effect of Uniaxial Fatigue Aging and Fabric Orientation on Low Impact Velocity Response of Glass Fibers/Elium Acrylic Composite Laminates

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4089
Author(s):  
Tomasz Libura ◽  
Rodrigue Matadi Boumbimba ◽  
Alexis Rusinek ◽  
Zbigniew L. Kowalewski ◽  
Tadeusz Szymczak ◽  
...  
Keyword(s):  
Impact Velocity ◽  
Impact Energy ◽  
Composite Structures ◽  
Glass Fibers ◽  
Impact Resistance ◽  
Woven Fabric ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Engineering Structures ◽  
The Impact

Impact resistance is one of the most critical features of composite structures, and therefore, its examination for a new material has a fundamental importance. This paper is devoted to the characterization of the fully recyclable thermoplastic ELIUM acrylic resin reinforced by glass fabric woven, which belongs to a new category of materials requiring advanced testing before their application in responsible elements of engineering structures. Its high strength, low weight as well as low production cost give excellent opportunities for its wide application in the automotive industry as a replacement of the thermoset-based laminates. The study presents an experimental work concerning the effect of damage due to low and high cyclic fatigue aging of two groups of specimens, first with the woven fabric orientations of [0°/90°]4 and secondly with [45°/45°]4, on the low impact velocity properties. The impact resistance was measured in terms of load peak, absorbed energy, penetration threshold and damage analysis. The low velocity impact results indicate that the uniaxial cyclic loading (fatigue aging) of the material leads to the reduction of impact resistance, especially at the high impact energy levels. Scanning Electron Microscopy (SEM) and Computed Tomography (CT) scan observations reveal that the damage area grows with the increase of both strain amplitude and impact energy.

The Measurement of the Velocity Outside the High Pressure Water Jet and Abrasive Water Jet Nozzle Based on the Energy Transfer Method

2010 ◽  
Vol 135 ◽  
pp. 361-364 ◽  
Author(s):  
Rong Guo Hou ◽  
C.Z. Huang ◽  
H.T. Zhu ◽  
Z.W. Niu
Keyword(s):  
High Pressure ◽  
Energy Transfer ◽  
Water Jet ◽  
Abrasive Water Jet ◽  
Impact Forces ◽  
Pressure Water ◽  
High Pressure Water Jet ◽  
Transfer Method ◽  
The Impact ◽  
Core Part

The energy transfer method is used to measure the flow velocity of the outside the high pressure water jet (WJ) and Abrasive water jet (AWJ) nozzle. The impact forces of the flow measured by the piezoelectricity ergometer will be transformed to the velocity value, the average velocity of the flow outside the nozzle will be obtained. The result indicates the velocity will reduce along the direction of the flow, and the velocity of the AWJ flow will reduced greatly than the WJ flow, which indicates that the length of the core part of the AWJ flow is shorter than the WJ Flow, the stand-off should be within the 0mm-15mm ranges to gain the most effective machining.

Parametric Analysis of the Dynamic Response of Hot-Rolled H-Shaped Steel Beam under Lateral Impact Load

2012 ◽  
Vol 215-216 ◽  
pp. 998-1002 ◽  
Author(s):  
Chang Pei ◽  
Rui Wang
Keyword(s):  
Dynamic Response ◽  
Impact Velocity ◽  
Impact Energy ◽  
Impact Load ◽  
Steel Beam ◽  
Lateral Impact ◽  
Analysis Model ◽  
Fea Model ◽  
Hot Rolled ◽  
The Impact

The analysis on the basic mechanical properties of hot-rolled H-shaped steel beam under lateral impact load was done by use of ABAQUS. The reliability of the FEA model was verified through comparing with the existing experiment of H-shaped steel beam subjected to lateral impact. And then, this FEA model was used to research the dynamic response of the H-shaped steel beam subjected to lateral impact. The main parameters include the impact energy, mass and impact velocity of the impact hammer. The results indicate that the finite element analysis model built in this paper could accurately simulate the process of hot-rolled H-shaped steel beam under lateral impact load and the impact energy, mass and impact velocity have different influences on the dynamic response of H-shaped steel beam.

scholarly journals Mathematical function for the transition curves description 

2012 ◽  
Vol 51 (No. 3) ◽  
pp. 85-90
Author(s):  
R. Chotěborský ◽  
D. Herák ◽  
V. Bezouška ◽  
P. Hrabě ◽  
M. Müller
Keyword(s):  
Impact Energy ◽  
Material Properties ◽  
Impact Test ◽  
Charpy Impact ◽  
Data File ◽  
Charpy Impact Test ◽  
Measured Data ◽  
Mathematical Function ◽  
The Impact ◽  
Transition Curves

Toughness is one of important material properties. At present steel is still the most used material. Owing to the temperature this material can fail both brittly and ductily. Therefore we look for the temperature above which the material will failur ductily. The Charpy impact test is one of methods how to determine the ductility by the temperature – transition access in the determined temperature range. The measured data file is large and it requires the interlay by a curve which presents the relation between the impact energy and the temperature.

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