Hammer Type Research Articles

Effect of Sheet Pile Driving on Geotechnical Behavior of Adjacent Building in Sand: Numerical Study

Construction vibration such as sheet pile driving can produce earthborn vibrations which may be leads to problems for the supporting soils and adjacent structures. Vibrations create the stress waves traveling outward from the source through the soil and cause structural damage due to dynamic vibration induced settlement. The main aim of the present research is to study the vibration effect through sheet pile driving technique on the surrounding soil and adjacent structure. A series of plain strain finite element analysis using Plaxis 8.2 dynamic module is run to simulate the installation technique of a sheet pile unit using driving technique (hammer type). The effect of construction stages with different embedded sheet pile depth, sand relative density, and foundation distance from the driving source is also studied. The influence of hammer driving amplitude on the foundation response and excess pore water pressure are presented. The results showed that the increase of both embedment sheet pile depth and hammer efficiency can significantly produce higher excess pore water pressure and foundation settlement. The increase of sand density can also has a great effect in increasing the foundation damage of adjacent structure compared with low sand relative density. The building damage can significantly take place when the driving is closed to foundation.

Rebound Hammer Tests of High-Strength Concrete: Effects of Internal Stress and the Shape of the Impact Area of the Test Specimens on the Measurement Results

This study examines the factors affecting the results of non-destructive testing of high-strength concrete performed on cubes and on cylinders and examines the processing of calibration relations. Tests were performed with both a type N and a type L Schmidt impact hammer (with a standard impact energy of 2.205 Nm and 0.735 Nm respectively). The assessed factors were internal stress in a specimen and the shape of the impact area. Test specimens were loaded by a force corresponding to the stress in specimen 0%, 10%, 20%, 30%, and 50% from the expected compressive strength. Rebound numbers of the unloaded test specimens were significantly lower than those of the loaded specimens. Therefore, calibration relations and/or correction coefficients processed by measurements of unloaded specimens can be assessed as unsuitable. To process calibration relations, we recommend exerting internal stress in amounts of 15% to 20% of the expected compressive strength of the tested HSC samples. During the determination of the effect of the shape of the test area on the cylindrical test specimen, it was assumed that the rebound numbers on the plane and the round test area would be the same. However, the test results revealed that the rebound numbers in the differently shaped test areas were different. For Schmidt impact hammer type N, the rebound numbers in the round test area were lower by 0.7 units on average, and for Schmidt impact hammer type L, the rebound numbers in the round test area were lower by 1.7 units on average compared to the plane test area rebound numbers.

Aspects regarding FEM simulation of stress in hammer mill working tool

Considering the need for development and improvement of biomass processing equipment, researchers bring contribution by making suggestions to design also through simulation and modelling of different stresses that occur on equipment’s working tools. In this paper the stress in hammer mill working tools was analysed using FEM simulation with the help of SolidWorks 2016 Premium, projecting the geometric model and FEM simulation for a MC 22 hammer mill. The hammer mill has a four bolts rotor on which are the hammer disposed. The hammer mills rotor frequency is about 2940 rot/min. An important result in FEM simulation was the fact that the maximum reaction in the hammer joint was 11635 N. After FEM simulation experimental research were done using shredded miscanthus and energetic willow, the mill being equipped alternately with 4 types of hammers, with corners processed differently.

Fluidic DTH hammer with backward-impact-damping design for hard rock drilling

Hard rock drilling is increasingly important due to progress in both the use of geothermal heat as a new energy source and the development of new unconventional gas fields. The DTH hammer drilling method is generally considered one of the best approaches for drilling hard rocks. A fluidic DTH hammer with backward-impact-damping design for hard rock drilling was proposed in the study. Striking features of this DTH hammer tool include extended life expectancy and capability to withstand drilling fluids solids content. A sequence of numerical and experimental investigations were performed on the newly designed fluidic DTH hammer. It is observed that the backward-impact-damping design is effective in protecting the fluidic oscillator from damage. Although the backward-impact-damping design may cause a decrease in the single-impact energy, the increased impact frequency can offset the aforementioned disadvantage to a certain extent. The paper brings attention to several interesting aspects of the fluidic DTH hammer. The accumulated data provide useful information to develop this type of a DTH hammer and facilitate its popularization and application in hard rock drilling.

Discovery of circa 115,000-year-old bone retouchers at Lingjing, Henan, China.

Most Chinese lithic industries dated between 300,000 and 40,000 are characterized by the absence of Levallois debitage, the persistence of core-and-flake knapping, the rarity of prepared cores, their reduction with direct hard hammer percussion, and the rarity of retouched flakes. Here we report the discovery of seven bone soft hammers at the early hominin Lingjing site (Xuchang County, Henan) dated to 125,000–105,000. These artefacts represent the first instance of the use of bone as raw material to modify stone tools found at an East Asian early Late Pleistocene site. Three types of soft hammers are identified. The first consists of large bone flakes resulting from butchery of large herbivores that were utilized as such for expedient stone tools retouching or resharpening. The second involved the fracture of weathered bone from medium size herbivores to obtain elongated splinters shaped by percussion into sub-rectangular artefacts. Traces observed on these objects indicate intensive and possibly recurrent utilization, which implies their curation over time. The last consists of antler, occasionally used. Lingjing bone tools complement what we know about archaic hominin cultural adaptations in East Asia and highlight behavioural consistencies that could not be inferred from other cultural proxies. This discovery provides a new dimension to the debate surrounding the existence of the Middle Palaeolithic in the region. The attribution of East Asian sites to the Middle Palaeolithic assumes that cultural traits such as the Levallois method represent evolutionary hallmarks applicable to regions of the world different from those in which they were originally found. Here, we promote an approach that consists in identifying, possibly from different categories of material culture, the original features of each regional cultural trajectory and understanding the behavioural and cognitive implications they may have had for past hominin populations.

Schmidt hammer rebound hardness tests for the characterization of ancient fired clay bricks

ABSTRACTThis article presents results of non-destructive Schmidt hammer tests performed on ancient fired clay bricks sampled from historical masonry. These tests were carried out in order to evaluate, and compare, the different degrees of degradation, depending on the bricks’ specific exposures and locations within a wall. The results indicate that this technique is sensitive enough to distinguish sample locations and measure weathering differences, even for different surfaces of a particular sample. For each case study, referenced surfaces were tested for bricks from a facade or interior wall. Each surface was tested with a Schmidt hammer type LB at ten different points of measurement, and these measurements were repeated ten times. For each impact at a particular point, a mean rebound value was calculated to provide an index of the degree of brick-surface microweathering.

A utilização do percutor em pedra branda na debitagem lamelar durante o Magdalenense na Estremadura portuguesa

O desenvolvimento de programas direccionados de talhe experimental em sílex permitiu identificar os estigmas relacionados com a utilização de percutores em pedra branda. Pelegrin (2000) explorou os limites e constrangimentos da utilização deste tipo de percutores e desde a publicação dos critérios distintivos, que permitem reconhecer esta técnica no material arqueológico, ela foi identificada em vários sítios e em diferentes cronologias na Europa e no Próximo Oriente. A identificação fortuita de estigmas evocativos da utilização de percutores em pedra branda na colecção lítica da camada 3 da Lapa dos Coelhos motivou um registo sistemático, desses atributos, durante o estudo de outras colecções magdalenenses da Estremadura portuguesa. Foram observados e registados os seguintes atributos: tipo de talão (cortical, liso, diedro, facetado, microfacetado, linear, punctiforme, esmagado e retocado), presença de labiado, vestígios de abrasão (ligeira ou marcada), presença de esquirolamento do bolbo, presença de fissuração do cone de percussão, existência de rugas finas concêntricas a partir do bolbo de percussão e presença de linha do talão irregular. A análise e quantificação destes estigmas de percussão permitiu identificar um número significativo de peças com evidência de debitagem por percutor brando (orgânico e mineral) mas a associação recorrente de caracteres distintivos leva a crer que a utilização de percutores em pedra branda terá sido significativa. Não dispomos de dados para uma comparação efectiva de toda a sequência regional do Paleolítico Superior, contudo, na amostra observada a utilização de um percutor de pedra branda parece ter aumentado a partir do Magdalenense final. Apesar de preliminares estes dados devem ser tidos em conta, uma vez que, esta informação é fundamental para a reconstituição das escolhas técnicas efectuadas no passado.

« La réussite d’une production repose sur l’attention prêtée aux détails »: l’exemple des débitages lamellaires par méthode du Raysse (Gravettien moyen, France)

Après un bref rappel historiographique sur le Gravettien moyen français (Noaillien et Rayssien), cet article se propose de faire le point sur les derniers développements concernant les burins-nucléus du Raysse et les lamelles de la Picardie (deux « fossiles directeurs » caractéristiques du Rayssien, c’est-à-dire la seconde phase du Gravettien moyen). Il s’agira de rappeler les objectifs de ces débitages lamellaires et les grands principes techniques qui les régissent tout en détaillant l’ensemble des pièces caractéristiques (burin-nucléus, lamelles de la Picardie, lamelles du Raysse) qui permettent de les reconnaitre. Ensuite, certains aspects morpho-dimensionnels et qualitatifs de la variabilité des lamelles de la Picardie et des burin-nucléus du Raysse seront détaillés à partir de quelques exemples (La Picardie, la Grotte-du-Renne et Solvieux). Pour finir, à partir de l’étude technologique des burins-nucléus du Raysse et de reconstitutions expérimentales, plusieurs détails techniques discrets inédits seront présentés. Ainsi, outre la préparation très particulière des talons à facettage latéralisé oblique, l’incidence du geste de percussion ainsi que le maintien du nucléus apparaissent aussi comme des éléments indispensables à la bonne mise en œuvre de la méthode du Raysse. La compréhension intime de ces éléments de détails relève d’une meilleure lecture technologique des assemblages tout autant qu’elle constitue un élément clef pour l’étude de l’évolution et de la transmission des systèmes techniques.

Hammering Does Not Fit Fitts' Law.

While movement is essential to human wellbeing, we are still unable to reproduce the deftness and robustness of human movement in automatons or completely restore function to individuals with many types of motor impairment. To better understand how the human nervous system plans and controls movements, neuromechanists employ simple tasks such as upper extremity reaches and isometric force tasks. However, these simple tasks rarely consider impacts and may not capture aspects of motor control that arise from real-world complexity. Here we compared existing models of motor control with the results of a periodic targeted impact task extended from Bernstein's seminal work: hammering a nail into wood. We recorded impact forces and kinematics from 10 subjects hammering at different frequencies and with hammers with different physical properties (mass and face area). We found few statistical differences in most measures between different types of hammer, demonstrating human robustness to minor changes in dynamics. Because human motor control is thought to obey optimality principles, we also developed a feedforward optimal simulation with a neuromechanically inspired cost function that reproduces the experimental data. However, Fitts' Law, which relates movement time to distance traveled and target size, did not match our experimental data. We therefore propose a new model in which the distance moved is a logarithmic function of the time to move that yields better results (R2 ≥ 0.99 compared to R2 ≥ 0.88). These results support the argument that humans control movement in an optimal way, but suggest that Fitts' Law may not generalize to periodic impact tasks.

IMPACT OF ADDING BIOGAS LIQUID SLURRY ON SOIL SURFACE ON PENETRATION RESISTANCE

In this study, the impact of adding biogas liquid slurry (BLS) on soil surface on soil penetration resistance (soil cone index) was investigated. The soil penetration resistance was measured using two types of penetrometers: a hand-held type and a hammer type. The BLS application rates were 0, 2, 4 and 6 lit/m2. The BLS was spread on the soil surface three days before measurements. The soil penetration resistance was measured up to a 20 cm depth in no-till sandy clay loam soil. The statistical analysis showed that the effects of the BLS application on the soil penetration resistance were significantly different (P < 0.05). The highest penetration resistance value was found in the control application (no BLS applied) and the lowest value was obtained in the BLS application of 6 lit/m2. The average values of soil penetration resistance measured by the two types of penetrometers within the penetration depth profile of 0–20 cm for the control treatment were 3756 kPa (hand-held type) and 3743 kPa (hammer-type). The lower soil penetration resistances were measured as 2315 kPa (hand-held type) and 2394 kPa (hammer-type) at a BLS application rate of 6 lit/m2. The results also showed that the soil penetration resistance was affected by BLS application rate and the penetration depth, and this effect can be predicted using the models generated from the study (within the investigated range of the variables). It could be concluded that adding BLS to the soil surface reduced soil penetration resistance, which may improve root growth and distribution. In addition, the study concluded that the effects of BLS application on soil properties and soil strength over longer periods should be further studied.

Breaking blades: Experimental programme on intentional fracturing systems of lithic tools

This research represents a first approach to the characterization of blade fractures produced intentionally using various techniques, according to an experimental protocol. The objective is to establish a reference base of marks which serve to define the fractures documented in the archaeological record.&#x0D; The fractured blade being a very common element in different sites throughout in the Iberian Peninsula during the Neolithic and Chalcolithic Ages. In fact, from the Late Neolithic a new concept applied to the creation of lithic tools arose, involving the fracturing of blades through the improvement of fracturing techniques. In addition, a preference for obtaining the mesial fragments of the blades or those which have more regular measurements can be observed. This type of lithic instrument represents high percentages of all the retouched material, and may possess only one fractured end or, more commonly, both, bi-fractured.&#x0D; With the archaeological evidence, we decided to carry out an experiment to define and classify the marks that result during the intentional fracturing of laminar fragments, contemplating different variables. We used three types of techniques for fracturing blades: flex, direct percussion and indirect percussion, and we used different types of hammer, made of stone, antler and copper.&#x0D; For the results, we have standardized the descriptions of different parts of the fracture distinguishing: types of fracture, fracture planes, fracture marks and macrowear. However, we should point out that this experimentation is the beginning of a line of research that, over time, must integrate a wider experimental base which also considers the other mentioned causes of fracture, as well as the functional objective of these tools.&#x0D; The preliminary study through this experimentation has made it possible to define and describe the types of fractures resulting from the use of different blade fracturing methods. We also have described the main types of fracture marks generated from each fracturing technique.

Influence of olive ripening degree and crusher typology on chemical and sensory characteristics of Correggiolo virgin olive oil.

In this study, two types of crusher, hammer and blade, were used to produce olive oils from cv. Correggiolo olives at four stages of ripeness, to analyse the effect of these two factors on oil quality indices (free acidity, peroxide value, UV absorption), on phenolic compounds content and sensory profiles. Differences in chemical and sensory data were analysed by two-way ANOVA. Ripeness exerted a stronger influence than the crushing equipment on quality indices, phenolic content and sensory evaluation; moreover the statistical significance of interaction between the factors considered suggests that they are intertwined. Differences in the texture of olive pastes obtained by squashing and crushing were clearly evident at the first stage of ripeness via observation with a scanning electron microscope. The stronger mechanical action of the hammer crusher also produced smaller pit fragments compared to the blade crusher, as shown by particle size analysis of the kernels fragments. Knowledge about the interaction between ripening and crushing will allow olive oil producers to pursue a product of the quality most suitable for a particular type of consumer. For example, bitterness and pungency, characters recently connected with health effects because sensory markers of extra virgin olive oil (EVOO) polyphenols, do not have a great sensory appeal for most consumers; however, there is a niche of gourmet estimators interested in these peculiar flavours and ready to pay a premium price for them. The producer will be able to customise the EVOO by modulating its chemical and sensory characteristics, especially the phenolic fraction, thus addressing the needs of consumers with different tastes. © 2016 Society of Chemical Industry.

Use of the Acoustic Energy Meter (AEM) for rapid geomorphological field assessment of rock hardness: comparison with Schmidt hammer R‐value

AbstractRapid, field‐based assessments of rock hardness are required in a broad range of geomorphological investigations where rock intact strength is important. Several different methods are now available for taking such measurements, in particular the Schmidt hammer, which has seen increasing use in geomorphology in recent decades. This is despite caution from within the engineering literature regarding choice of Schmidt hammer type, normalization of rebound (R‐) values, surface micro‐roughness, weathering degree and moisture content, and data reduction/analysis procedures. We present a pilot study of the use of an Acoustic Energy Meter (AEM), originally produced, tested and developed within the field of underground mining engineering as a rapid measure of rock surface hardness, and compare it with results from a mechanical N‐Type Schmidt hammer. We assess its capabilities across six lithological study sites in southeast Queensland, Australia, in the Greater Brisbane area. Each rock exposure has been recently exposed in the 20th/21st century. Using a ‘paired’ sampling approach, the AEM G‐value shows an inverse relationship with Schmidt hammer R‐value. While both devices show variability with lithology, the AEM G‐values show less scatter than the Schmidt hammer. We conclude that each device can contribute to useful rock hardness testing in geomorphological research, but the AEM requires further field testing in a range of environments, and in particular on older and naturally‐exposed rock surfaces. Future evaluations can extend this pilot study by focusing on sampling procedures, energy sources, and data reduction protocols, within the framework of a comparison study with other rock hardness testing apparatus. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Failure mechanisms and structural optimization of shredder hammer for metal scraps

Recycling retired cars can relieve the environmental pollution and resource waste efficiently. However, a few publications can be found on the failure mechanisms and optimization method of recycling equipment, shredders. Thus, the failure mechanisms and structural optimization of shredder hammers for retired cars are studied aiming improving shredding efficiency and reducing cost. Failure types of shredder hammer are studied theoretically, and it is found that wear failure and fatigue failure are the two main failure types of shredder hammer. The shredding process of metal scraps is analyzed by finite element method, and it can be divided into four stages based on the stress states: initial stage, collision stage, grinding stage and separation stage. It is proved that the shredding efficiency can be improved by increasing cutouts on the hammer head. Finally, it is determined that the hammer with two cutouts is the optimal structure for metal scraps, which can improve the shredding efficiency by 20% and lengthen the hammer life by 15%. This study provides scientific basis for the industry application and theoretical foundation for further research.

Способ оптимизации повышения износостойкости молотков кормодробилок

The aim of the study is the reliability of feed mill´s improvement by the study of hammer´s design parameters and the choice of the materials for its manufacture. The object of study is the process of the hammer´s wear in a feed mill of the hammer type. The results of theoretical re-search to improve the wear resistance of feed mill hammers´ are given. Analyzing feed mill work, we came to the conclusion that the hammer deviates from the radial position to the corner α. Theoretical calculations found that to avoid grain´s slipping on a hammer of a feed mill, a hammer with known cutting edge´s angle of 16-18º must be manufactured.

SOME ENGINEERING FACTORS AFFECTING THE PREPARATION OF MORINGA RESIDUES FOR ANIMAL DIETS

Moringa oleifera, a rapid growing tree found in a different climatic condition, the moringa is a promising tree and has the potential to become a new source of fresh forage material per unit area compared to other forage crops high productivity. Moringa produce a large amount of the residues consisting of branches and stalks which lefts over after getting moringa leaves for human use, causing environmental problems. Therefore, the main objectives of this research are to prepare moringa residues to be used as a dietary supplement for animals feed due to it's content of many nutrients, protein sources and vitamins, to decrease the cost of the feed. Meanwhile the essential factor is preventing the accumulation of these quantities and environment pollution. Some physical, mechanical properties and chemical composition of moringa residues were investigated at moisture content (8%). In order to determine engineering treatments to get the most appropriate lengths for cutting of moringa residues to be used as appropriate residues roughage for animal diets. A local manufacture hammer mill machine was used for crushing and milling the moringa residues, three different types of hammer were used in this machine to cut the right lengths. The current research focus on machine noise levels and air pollution dust particle due to crushing and milling the moringa residues for human safety. The quantity of fine particles inhaled and produced from a local hammer mill machine operator was recorded. The microbiological analysis showed the presence of microorganisms such as Bacteria, Fungi, Actinomyces and Yeasts in the moringa dust particles. The nutritional characteristics of stems (stalks) of Moringa oleifera plant with two levels of grinding (fine and coarse Moringa oleifera stems) _______________________________________ 1 Researcher, Agricultural Engineering Research Institute (AEnRI), Agricultural Research Center (ARC), Dokki. Egypt. 2Prof., Animal Production Research Institute, (ARC), Dokki. Egypt. (Fine MOS; from > 0.6 mm to 1.4 mm and Coarse MOS; from >1.4 mm to 6.7 mm) and clover hay (CH) were studied in a completely randomize design using: chemical composition In-vivo digestibility coefficients and feeding values determination. Results revealed that crude protein (CP) content was 12.81, 12.24 and 13.08% for (Fine MOS and Coarse MOS) and clover (CH), respectively. The MOS had high crude fiber (CF) content than CH, while recorded high ether extract (EE) 3.12% content while stems recorded low EE 1.03 and 0.94% content. The fiber fraction (NDF, ADF, ADL, cellulose and hemicellulose) of MOS content were higher than those in CH content. Fine MOS) with highest nutrient digestibility, TDN (50.72%) and DCP (8.39%), followed by coarse MOS (TDN, 48.46% and DCP, 7.12%). Meantime, intermediate values of nutrients digestibility of clover hay led to intermediate TDN and DCP values (45.41and 8.14%) respectively. The results revealed that fine grinded Moringa oleifera stalks had great potential as livestock feed for small ruminants holder, especially during dry season and it consider a good quality roughage compare to clover hay.

Substantiation of type and parameters of downhole air hammer with a view to increase small diameter hole drilling velocity

The article substantiates the need of designing a rotary–percussion drilling tool to drill holes 40–60 mm in diameter and to 50 m long. The drilling rig with a downhole air hammer has been designed and manufactured. The authors have carried out analytical and experimental research to determine drilling velocity in different rocks of varying hardness.

Rock Mass classification using three types of hammers at the quarry sites of Gokayama Dam

Rock Mass classification using three types of hammers at the quarry sites of Gokayama Dam

The relationship between the rock classification using three types of hammers and strength of rocks

The relationship between the rock classification using three types of hammers and strength of rocks

Mechanics of the implosion of cylindrical shells in a confining tube

A fundamental experimental investigation, with corresponding computational simulations, was conducted to understand the physical mechanisms of implosions of cylindrical shells occurring within a tubular confining space which has a limited potential energy reservoir. In particular, attention was focused on studying the generation of pressure waves from the implosion, the interaction of the pressure waves with the confining tube walls and end caps, and the collapse mechanisms of the implodable volume. Experiments were conducted with three implodable volume geometries which had similar critical collapse pressures. The implodable volumes were aluminum 6061-T6 cylindrical tubing and were placed concentrically within the confining tube. Pressure histories recorded along the length of the confining tube during the experiments were utilized to analytically evaluate the deformation of the implodable volume using fluid–structure coupled deformation models. Computational simulations were conducted using a coupled Eulerian–Lagrangian scheme to explicitly model the implosion process of the tubes along with the resulting compressible fluid flow. The numerical model developed in this study is shown to have high correlation with the experimental results and will serve as a predictive tool for the simulation of the implosion of different cylindrical geometries as well as various tube-in-tube implosion configurations. The experimental results show that the limited hydrostatic potential energy available in a confined environment, as compared to a free field, significantly influences the implosion process. The wall velocities of the implodable volume during the collapse, as well as the extent of the collapse progression, are largely affected by the sudden decrease in the available hydrostatic potential energy. This energy is shown to be partially transformed into elasto-plastic strain energy absorbed in the deformation of the implodable volume, as well as the kinetic energy of the water during the implosion process. Experiments also show that the extent of the collapse progression of an implodable volume can potentially be inhibited within a closed environment, which can lead to the arresting of an implosion event prior to completion for larger implodable volumes. The pressure waves generated during collapse comprise of waves emitted due to the impact of the implodable volume walls, the arrest of rushing water and contact propagation along the walls. These processes later evolve into water hammer type axial wave behavior.