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Gleb Moses
Gleb Moses

Article Spinner 5 0 Cracked [TOP]

That's right -- the task of oiling the spinners fell onto young boys who were just entering their teenage years and who made about 30 or 40 cents for a day's work. Because the parts of the machine that had to be lubricated were at the crotch level of the workers, they sprayed oils that would get into their pants, and thanks to the piss-poor hygiene of the workers, it would then seep right into the skin. Of their balls.

Article Spinner 5 0 Cracked

The condition produced painful-looking sores on the surface of the scrotum that penetrated deeper, affecting the testicles, then the abdomen, and eventually resulting in death. Over a period of just 20 years, there were about 500 deaths from "mule spinners' cancer," but that's not too surprising, considering that the preferred treatment of the condition among doctors was to dose their poor victims with -- you guessed it -- mercury.

How does this happen? Well, grab a piece of paper and light it. See how quickly it burns? Now wad another piece tightly into a ball and try it again. See how much harder it is to light now? That's because the flat paper is all surface area -- fires need oxygen, and anything with lots of surface area has a better chance of burning. But tiny particles of dust are nothing but surface area. So it doesn't matter how harmless and nonflammable the substance is as a solid -- break it up into tiny bits and mix it with air, and you've got the potential to leave a goddamned crater in the ground.

Elorm Kojo Ntumy would like to thank Georgette for her help in completing this article. Joey Clift is a sketch comedy writer and performer living in Los Angeles. He's written bits and segments for Scare Tactics on SyFy, Tosh.0 on Comedy Central, and World's Deadliest on National Geographic Wild. His sketch group Dumbshit Mountain can be found on YouTube and Facebook.

In turbofan engine, ice accretion on a spinner cone may lead to a decline in the engine aerodynamic performance and an increase of the vibration amplitude of the engine. The shedding ice debris from the spinner cone may damage fan blades and endanger flying safety. An understanding of the mechanisms responsible for the ice shedding process is necessary to optimize the design of spinner cone and de-icing system to avoid hazardous ice shedding. The combination of ice adhesive and cohesive failure leads to the complexity of the ice shedding from a rotating spinner cone. In this paper, a novel ice shedding model for a spinner cone with consideration of ice cohesive and adhesive failure is proposed. The cohesive zone material model is applied to simulate the initiation and propagation of ice/spinner cone interface crack. The extended finite element method is introduced to model crack growth inside the ice. The ice shedding process from a spinner cone is explained and analyzed by using the combination of cohesive zone material and extended finite element method. Some factors that affect the break-up and shedding of the ice are discussed, which include the mechanical properties of the ice and ice/spinner cone interface. A preliminary validation of this model is carried out through the comparison of numerical results and experimental data. This model can provide useful information for further study on the ice debris trajectory prediction and ice impact analysis.

Ice accretion on a turbofan engine could cause serious problems and result in serious aircraft accidents. From an engine system level, there exist four types of icing effect: vibration, operability, temporary thrust/power loss, and components damage [1]. The spinner cone is in the front of the engine, and it is easy to encounter icing problems. Ice accretion on the spinner cone can cause unbalanced weight, and the vibration amplitude of the engine will increase. It also can block the flowpath and may cause engine stall, surge, and resonance, which may lead to temporary thrust/power loss. Shedding ice debris from the spinner cone can damage fan and compressor components. Certification procedures have been established to ensure safe operation for the engine under icing conditions. Though significant efforts have been devoted to the research of icing physics and icing protection, a successful prediction of icing accretion and shedding still requires further studies and improvements. An understanding of the mechanisms responsible for the ice shedding process is necessary to optimize the spinner cone design to avoid hazardous ice shedding. The combination of ice adhesive and cohesive failure leads to the complexity of the ice shedding from a rotating spinner cone. In this paper, ice adhesive failure is defined as the occurrence of failure near or at the ice/substrate interface, and cohesive failure is defined as the occurrence of failure in the ice. A novel ice shedding model for a spinner cone with consideration of ice cohesive and adhesive failure is proposed in this paper.

The character of ice shedding from a spinner cone is closely related to many factors, which may include the shape of the cone, ice/spinner cone interface adhesion strength and icing conditions (temperature, supercooled water droplet size, freestream velocity, spinner cone rotating speed, etc.). Figure 6 shows a schematic plot of a block of ice shedding from the surface of a spinner cone. Note that the x axis is the axis of rotation of the spinner cone. The necessary condition of the occurrence of ice shedding phenomenon is that a block of ice is surrounded by interface cracks and internal cracks, which initiate and propagate under centrifugal loading and additional bending moment. More specifically, the propagation of interface cracks and internal cracks are driven by radial stress, hoop stress, and bending stress along longitudinal direction. As a result of the crack propagation, both adhesive failure and cohesive failure may occur. In this paper, at least three main internal cracks are assumed to be part of the ice shedding necessary condition, which could be classified by their directions. Namely, two of the main internal cracks are longitudinal cracks, and one is a circumferential crack. The sequence of the initiation of interface cracks and internal cracks is highly dependent on the ice shape, ice type (glaze ice, rime ice, and mixed ice). The interface strength of the ice/substrate is also a very important factor, which is related to the material, roughness, and temperature. After comparing the stress analysis results with the experimental results, we made assumptions about cracks initiation sequence as follows. One or two longitudinal cracks first initiate due to high hoop stress in the process of ice accretion.Interface crack initiates due to centrifugal loading and high radial stress.Circumferential or latitudinal crack(s) initiate due to bending loads and high axial stress.

Figure 7 shows the block diagram of ice shedding simulation process, and each step is described in detail thereafter. The whole process is fully automatically executed. First, the ice shape image is processed by using image processing technology and then digitized. The ice shape geometry data are used to generate finite element mesh. Then, the ice mechanical property and the centrifugal loading are defined and input. The boundary condition is imposed on the spinner cone, and the ice is bonded with the surface of the spinner cone by contact elements with initially bonding conditions, and the contact elements have a cohesive zone material property. Thus, it does not need to apply boundary condition on the ice. Before the detailed simulation is carried out, a preliminary stress analysis is performed to find out possible locations of an interface crack, and an internal crack may initiate. In this paper, according to the assumptions, XFEM models will be generated, and enrichment will be imposed on these locations where a longitudinal crack may initiate and propagate. After this step, the boundary conditions will be imposed on the CZM model to simulate the debonding process of the interface between ice and spinner cone. Finally, detailed stress analysis is performed by using XFEM model, and the program will predict if there exists local or whole failure in the ice or in the interface and if ice shedding will occur. If the ice shedding does not occur, the program will import a new ice shape at the next time step and repeat the preceding calculation until the ice shedding occurs.

When using this CZM and XFEM in calculating ice shedding problems in this paper, some assumptions are as follows. Between the ice and spinner cone surface, only adhesive failure may occur. The cohesive failure is ignored.The ice and the spinner cone surface are initially perfectly bonded.The ice is homogeny, with no porosity or air bubble in the ice.

Several FE models are built to calculate the stress in the ice and simulate the interface debonding and crack growth process. For the preliminary stress analysis, five two-dimensional (2-D) axial symmetry FE models are built, as shown in Fig. 8. For the longitudinal crack initiation and growth simulation, six 2-D FE models are built near the end of the ice with different dimensions, as shown in Fig. 9. For the interface failure analysis, a three-dimensional (3-D) FE model is used, as shown in Fig. 10. A 30 deg segment of the spinner cone and the ice is used to generate the FE mesh. Here, the value of 30 deg is assumed. The spinner cone and ice FE meshes consist of 44,751 and 71,967 3-D eight-node structural solid elements, respectively. In the interface between the spinner cone and ice, 4914 interface elements are generated, whereas in the final ice shedding simulation, a 2-D FE model similar to FE model for the preliminary stress analysis is used with some modifications, which include clearing the elements in the spinner cone, enrichment of the elements for XFEM analysis, and transferring the correspondent displacement on the interface nodes, as shown in Fig. 11. Typically, the average size of the elements in the spinner cone and ice is 0.5 mm. On the interface between the spinner cone and the ice, the FE mesh is refined to capture the process of ice/substrate debonding. A mesh sensitivity study has been carried out, and the stress results in the ice with different mesh densities is shown in Table 2. It can be seen that, with the increasing of the mesh density, the maximum stress in the ice is increasing. If the stress is normalized by dividing maximum stress using the fine mesh, the normalized stress using 0.5 mm mesh size is 0.9961, which is very close to 1.0. This result demonstrates that this element size is indeed sufficiently small for stress analysis and ice shedding analysis.


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