Research on Cutting Mechanism and Cutting Force Theoretical Model Based on Indentation Fracture Mechanics in Turning Lithium Disilicate Glass

Based on the theory of energy transfer, this study analyzes the fracture mechanism of machinable ceramics, and establishes the machinable ceramic tool-workpiece-chip coupling cutting force model. Research on the brittleness removal of hard and brittle materials by indentation test. The pre-existing defects on the surface of the workpiece are subjected to tensile stress. With continuous loading on a certain point on the surface of the workpiece, the cracks begin to sprout and expand; when the critical load is loaded, the cracks become unstable; with the load continues, the conical cracks expand in an unstable state. The Hertz crack system is obtained at the end of the indentation. The crack system model is established based on indentation fracture mechanics. According to Griffith energy balance theory, different types of energy models of the crack system are established. The theoretical model of cutting force is established according to the principle of energy conservation, the tool input is equal to the energy change between crack systems. The results of turning experiments show that the main cutting force increases with the increase of the radius of the tool nose, and decreases with the increase of the tool rake angle. The calculated values of the theoretical model of cutting force in turning of hard and brittle materials are basically consistent with the experimental values.

Imaging damage zones and fault growth processes with high-precision relocations of earthquake sequences.

<p>The architecture of fault damage zones combines various elements. Halos of intense fracturing forms around principal slip planes, possibly resulting from the shearing of slip surface rugosity or from dynamic stresses caused by earthquake ruptures. Splays forming off the tips and off the edges of a growing fault result in larger scale fracture networks and damage zones. Faults also grow by coalescence of en-echelon segments, such as Riedel fractures in a shear zone, and stress concentration at the steps results in linking damage zones. We show that these various elements of a shear-crack system can be recognized at seismogenic depth in earthquake sequences. Here we examine high-precision, absolute earthquake relocations for the Mw5.7 Magna UT, Mw6.4 Monte Cristo CA and Mw 5.8 Lone Pine CA earthquake sequences in 2020. We use iterative, source-specific, station corrections to loosely couple and improve event locations, and then waveform similarity between events as a measure for strongly coupling probabilistic event locations between multiplet events to greatly improve precision (see presentation EGU21-14608, and Lomax, 2020). The relocated seismicity shows mainly sparse clusters of seismicity, from which we infer multi-scale fault geometries. The uncertainty on earthquake locations (a few hundred meters) is typically larger than the width of halo damage zones observed in the field so that it is not possible to distinguish small aftershocks that could occur on a fracture within the halo or on a principal slip plane.</p><p>The relocated Magna seismicity shows a west-dipping, normal-faulting mainshock surface with an isolated, mainshock hypocenter at its base, surrounded up-dip in the hanging wall by a chevron of complex, clustered seismicity, likely related to secondary fault planes. This seismicity and a shallower up-dip cluster of aftershock seismicity correspond to clusters of background seismicity. The Lone Pine seismicity defines a main, east-dipping normal-faulting surface whose bottom edge connects to a steeper dipping splay, surrounded by a few clusters of background and reactivated seismicity. The space-time relation between background seismicity and multi-scale, foreshock-mainshock sequences are clearly imaged. The Monte Cristo Range seismicity (Lomax 2020) illuminates two, en-echelon primary faulting surfaces and surrounding, characteristic shear-crack features such as edge, wall, tip, and linking damage zones, showing that this sequence ruptured a complete shear crack system. In this example the width of the damage zone increases toward the earth surface.  Shallow damage zones align with areas of dense surface fracturing, subsidence and after-slip, showing the importance of damage zones for shaking intensity and earthquake hazard.</p><p>For all three sequences, some of the seismicity clusters delineate planar surfaces and concentrate along the edges of the suspected main slip patches. Other clusters of seismicity may result from larger scale damage associated with splay faults, en-echelon systems and linking zones, or with zones of background seismicity reactivated by stress changes from mainshock rupture. These types of seismicity and faulting structures may be more developed in the case of a complex rupture on an immature fault</p><p>__<br>Lomax (2020) The 2020 Mw6.5 Monte Cristo Range, Nevada earthquake: relocated seismicity shows rupture of a complete shear-crack system. https://eartharxiv.org/repository/view/1904</p>

High-precision, absolute earthquake location based on waveform similarity between events and application to imaging foreshocks, fault complexity and damage zones for recent western US earthquakes.

<p>We present a high-precision, absolute earthquake location procedure (NLL-SSST-coherence) based on waveform similarity between events and using the probabilistic, global-search NonLinLoc (NLL) location algorithm. NLL defines a posterior probability density function (PDF) in 3D space for absolute hypocenter location and invokes the equal differential-time (EDT) likelihood function which is very robust in the presence of outlier data. For NLL-SSST-coherence location we take initial NLL locations and iteratively generate smooth, 3D, source-specific, station travel-time corrections (SSST) for each station and phase type and an updated set of locations. Next, we greatly reduce absolute location, aleatoric error by combining location information across events based on waveform coherency between the events. This absolute coherency relocation is based on the concept that if the waveforms at a station for two or more events are very similar (have high coherency) up to a given frequency, then the distance separating these “multiplet” events is small relative to the seismic wavelength at that frequency. The NLL coherency relocation for a target event is a stack over 3D space of the event’s SSST location PDF and the SSST PDF’s for other similar events, each weighted by the waveform coherency between the target event and the other event. Absolute coherency relocation requires waveforms from only one or a few stations, allowing precise relocation for sparse networks, and for foreshocks and early aftershocks of a mainshock sequence or swarm before temporary stations are installed.</p><p>We apply the NLL-SSST-coherence procedure to the Mw5.8 Lone Pine CA, Mw5.7 Magna UT and Mw6.4 Monte Cristo NV earthquake sequences in 2020 and compare with other absolute and relative seismicity catalogs for these events. The NLL-SSST-coherence relocations generally show increased organization, clustering and depth resolution over other absolute location catalogs. The NLL-SSST-coherence relocations reflect well smaller scale patterns and features in relative location catalogs, with evidence of improved depth precision and accuracy over relative location results when there are no stations over or near the seismicity.</p><p>For all three western US sequences in 2020 the NLL-SSST-coherence relocations show mainly sparse clusters of seismicity. We interpret these clusters as damage zones around patches of principal mainshock slip containing few events, larger scale damage zone and splay structures around main slip patches, and background seismicity reactivated by stress changes from mainshock rupture. The Monte Cristo Range seismicity (Lomax 2020) shows two, en-echelon primary slip surfaces and surrounding, characteristic shear-crack features such as edge, wall, tip, and linking damage zones, showing that this sequence ruptured a complete shear crack system. See presentation EGU21-13447 for more details.</p><p>Lomax (2020) The 2020 Mw6.5 Monte Cristo NV earthquake: relocated seismicity shows rupture of a complete shear-crack system. Preprint: https://eartharxiv.org/repository/view/1904</p><p> </p>

Mapping the Bubble Trap Feeding Eruptions of Strokkur Geyser, Iceland

<p>Geysers are characterized by regular eruptions of hot water fountains. Their internal system consists of a heat source at depth, an often complex crack system and a conduit linking it to the surface. The conduit and crack system is filled with water, steam and gases similar to a volcano. Bubble traps are sometimes and rarely mapped and alternative heat-driven models for geyser eruptions exist.</p><p>Using a multidisciplinary, dense and close network of video cameras, seismometers, water pressure sensors and a tiltmeter we studied pool geyser Strokkur in June 2018. These multidisciplinary observations and particle-motion based tremor locations enabled us to derive a schematic cross section describing the driving mechanisms and the fluid dynamic processes within the bubble trap, crack system and conduit. We imaged a bubble trap at 23.7+-4.4 m depth, 13 to 23 m west of the conduit. We divide the eruptive cycle into eruption, refilling of the conduit, gas accumulation in the bubble trap and a trail of bubbles from the bubble trap into the conduit where they collapse at depth and have gained novel insights in understanding the gas accumulation, migration and collapse in such hot geyser systems in different phases of the eruptive cycle.</p><p>The dataset of this experiment can be accessed here:</p><p><strong>- Eibl, E. P. S.</strong>, Müller, D., Allahbakhshi, M., Walter, T. R., Jousset, P., Hersir, G. P., Dahm, T., (2020) ' Multidisciplinary dataset at the Strokkur Geyser, Iceland, allows to study internal processes and to image a bubble trap.' GFZ Data Services. DOI: 10.5880/GFZ.2.1.2020.007</p><p>- <strong>Eibl, E. P. S.</strong>; Walter, T.; Jousset, P.; Dahm, T.; Allahbakhshi, M.; Müller, D.; Hersir, G.P. (2020): 1 year seismological experiment at Strokkur in 2017/18. GFZ Data Services. Other/Seismic Network. DOI:10.14470/2Y7562610816</p>

PENGARUH PEMAKAIAN HYDROCARBON CRACK SYSTEM (HCS) TERHADAP PERFORMA SEPEDA MOTOR SUPRA X 125 TAHUN 2009

Kendaraan bermotor di Indonesia yang menjadi sumber emisi gas buang terbesar adalah sepeda motor. Ini merupakan kurangnya perhatian pengguna kendaraan bermotor dengan perbandingan kompresi mesin kendaraan yang tinggi cenderung memilih mengisi bahan bakar sepeda motornya dengan premium yang harganya lebih murah namun memiliki angka oktan yang rendah. Hal ini tentu akan menimbulkan masalah terhadap pembakaran yang tidak sempurna. Efek yang ditimbulkan adalah menyebabkan meningkatnya polutan pencemaran udara. Untuk mengatasi permasalahan diatas adalah dengan cara menggunakan Hydrocarbon Crack System (HCS), HCS bekerja untuk menyempurnakan proses pembakaran, sehingga dapat menurunkan kadar emisi gas buang kendaraan. Tujuan dari penelitian ini melihat pengaruh penggunaan Hydrocarbon Crack System (HCS) terhadap performa dan kandungan emisi gas buang yang dihasilkan. Berdasarkan hasil penelitian diperoleh bahwa penggunaan HCS pada sepeda motor Honda Supra X 125 dapat menurunkan emisi gas CO sebesar 40 %. Untuk emisi gas HC penggunaan HCS dapat menurunkan emisi gas HC sebesar 37%,sedangkan untuk emisi gas buang CO2 penggunaan HCS dapat meningkatkan emisi gas CO2 sebesar 12.98%. Motor vehicles in Indonesia which are the largest source of exhaust emissions are motorbikes. This is the lack of attention of motorized vehicle users with high engine compression ratios, which tend to choose to refuel their motorbikes with premium which is cheaper but has a low octane number. This of course will cause problems with incomplete combustion. The resulting effect is to increase air pollutants. To overcome the above problems is by using the Hydrocarbon Crack System (HCS), HCS works to improve the combustion process, so that it can reduce the levels of vehicle exhaust emissions. The purpose of this study is to see the effect of the use of the Hydrocarbon Crack System (HCS) on the performance and content of the resulting exhaust emissions. Based on the research results, it was found that the use of HCS on a Honda Supra X 125 motorcycle could reduce CO gas emissions by 40%. For HC gas emissions, the use of HCS can reduce HC gas emissions by 37%, while for CO2 exhaust emissions, the use of HCS can increase CO2 emissions by 12.98%.

PENGARUH PENGGUNAAN TEKNOLOGI HYDROCARBON CRACK SYSTEM TERHADAP KONSUMSI BAHAN BAKAR SEPEDA MOTOR HONDA MEGAPRO

Sepeda motor merupakan alat transportasi yang jumlahnya semakin meningkat di Indonesia. Peningkatan jumlah sepeda motor berpengaruh terhadap peningkatan jumlah konsumsi bahan bakar. Peningkatan konsumsi bahan bakar dapat diatasi dengan salah satu cara yaitu melakukan penghematan bahan bakar pada sepeda motor menggunakan teknologi Hidrokarbon Carbon Crack System (HCS). Tujuan dari penelitian ini adalah mendeskripsikan pengaruh penggunaan teknologi HCS terhadap konsumsi bahan bakar sepeda motor Honda MegaproJenis penelitian ini merupakan penelitian eksperimental. Sampel dalam penelitian ini adalah sepeda motor Honda Megapro 150 cc tahun 2004. Teknik pengambilan sampel dalam penelitian ini menggunakan teknik purposive sample. Pengujian dilakukan dengan cara mengukur waktu yang diperlukan mesin untuk menghabiskan bahan bakar dalam volume tertentu pada putaran mesin 1500-6500 rpm dengan selisih setiap pengujian sebesar 500 rpm. Analisa data menggunakan metode deskriptif komparatif. Setelah semua data diperoleh, kemudian hasilnya dibandingkan antara data pengujian konsumsi bahan bakar sepeda motor standar dengan sepeda motor yang menggunakan teknologi HCS.Hasil dari penelitian ini menunjukkan pada putaran mesin antara 1500-6500 rpm menggunakan katalis ganda spiral HCS (panjang 500 mm) dengan satu tabung Pertamax dengan volume satu liter, konsumsi bahan bakar spesifik menurun sebesar 40,21%. Pada putaran mesin yang sama menggunakan katalis ganda spiral HCS (panjang 500 mm) dengan dua tabung Pertamax dengan volume dua liter, konsumsi bahan bakar spesifik menurun sebesar 51,80%. Hasil penelitian menunjukkan bahwa penggunaan katalis ganda pada HCS memiliki pengaruh yang baik terhadap konsumsi bahan bakar. Penggunaan HCS dengan katalis ganda dan menggunakan dua buah tabung bahan bakar dapat lebih meningkatan efisiensi bahan bakar. Kata kunci: hidrocarbon crack system, konsumsi bahan bakar, otomotif.