Finite Element Analysis of Fiber Cement Corrugated Roofing Sheet under Bending

The study presents a numerical model for evaluation of the stresses in corrugated sheets under bending. The numerical analysis was performed from a three dimensional finite element model. From the analysis, the most intense tensional stress occurs in the trough and bottom surface of the corrugated sheet. While the most intense value of compressive stress occur in the crest and top surface of the sheet. Based on the principal stress contour diagram, the researcher also observed that the maximum uniformly distributed load carrying capacity of the fiber-cement corrugated sheet under bending, considering the linear material properties is 710N.

Magnetostratigraphy and Kinematic Characteristics of Datca Graben (Mugla, SW Turkey)

<p>This study involves kinematic development and magnetostratigraphy of infill of the Datça Graben located at the southwesternmost corner of Anatolia (Turkey). The study comprises kinematic analysis based on fault slip data collected from the margins of the Datça Graben and the magnetostratigraphic analysis of infill of the Datça Graben. For the kinematic analysis, 977 fault-slip data were collected from 44 sites. The data are analyzed using a software which is based on Angelier’s reduced stress tensor algorithm. For the magnetostratigraphic analysis, 344 samples are used and the paleomagnetic measurements of those samples are performed in the Fort Hofddjik Paleomagnetism Laboratory, University of Utrecht.</p><p>The results of the kinematic analysis have shown that the Datça Basin has developed under the effects of N-S-directed tensional stress regime manifested by WNW-ESE- striking normal faults. As a result of paleomagnetic measurements, the infill sediments of the Datça Graben can be represented by a reversed-normal-reversed polarity pattern, which can be correlated to C2r.1r-C2r.1n-C2r.2r subchrons within the C2r chron of the Early Matuyama in Geomagnetic Polarity Time Scale. This means that the graben filling sediments deposited between 2.3 Ma to 1.9 Ma, in the Late Pliocene.</p><p>This age interval suggests that the Datça Graben has completed its development from half-graben to full-graben geometry by the effects of syn-sedimentary WNW-ESE-striking faults in the Late Pliocene.</p><p>This thesis is supported by TUBITAK (Grant No: 117R012).</p>

Horizontal tensional stress and mountain development : In example of Gilbert Range and Khuren Khanan Range, Mongolia

Results of analysis of schematic geological cross section constructed using satellite image interpretation and 1:200 000 scale geological map through the Tavan Zagiin Khooloi, Gilbert Range, Dund Goliin Khooloi and Khuren Khanan Range are represented in this paper. Our results show that within the above mentioned mountain ranges decollement faults formed due to S to N trending tensional tectonic stress and, moreover, numerous thrust and back-thrust faults formed perpendicular to them. SW-NE, N-S trending tensional stresses are dominant in the western part of Mongolia and northwestern part of China. Interaction forces opposing them are the circumstances of forming new thrust faults in the Tavan Zagiin Khooloi and Dund Goliin Khooloi. Along the existing thrust faults, the Gilbert Range and Khuren Khanan Range were formed. Mountain blocks were uplifted due to the back-thrust faults and crustal thickening took place. As a result of horizontal tensional stress, the mountain development and shortening occurred. Хэвтээ чиглэлтэй хүчний үйлчлэл ба уул үүсэх хөдөлгөөн: Гилбэртийн нуруу, Хүрэн ханангийн нурууны жишээн дээр Хураангуй: Таван загийн хоолой, Гилбэртийн нуруу, Дунд голын хоолой, Хүрэн ханангийн нурууг хамарсан, тэдгээрт хөндлөн буюу өргөргийн дагуу чиглэлтэй геологийн тойм зүсэлтийг сансрын зургийн тайлал, 200000 масштабтай геологийн зургууд ашиглан хийсэн ажлын үр дүнг энд үзүүлсэн болно. Геологийн тойм зүсэлтээр дээрх нэр бүхий газруудад У-Х хэвтээ чиглэлтэй шахах тектоник хүчний үйлчлэлээс үүссэн деколлемент хагарал, түүнд хөндлөн чиглэлтэй үүсч буй олон тооны тохролтот болон эсрэг тохролтот хагарлуудын үйлчлэл хэрхэн нөлөөлж байгааг тайлбарласан үр дүнг толилуулж байна. Манай орны баруун хагас, Хятадын баруун хойд хэсэгт БУ-ЗХ, У-Х чиглэсэн хэвтээ чиглэлтэй тектоник хүч, харин түүний эсрэг үйлчлэх тулах хүчнүүдийн харилцан үйлчлэлээс үүдэн Таван загийн хоолой, Дунд голын хоолойд шинээр тохролууд үүсч байгаа бол Гилбэрт, Хүрэн ханангийн нуруунд өмнө нь үүссэн тохролуудын дагуу хавтангууд бие биенийхээ дээгүүр давхралдах, эсрэг тохролтот хагарлаар хавтангууд дээш шахагдан гарснаар уул, нурууд улам өндөрсөж, тасралтат хавтан улам зузаарч байна. Хэвтээ чиглэлтэй шахах хүчний үйлчлэлийн үр дүнд агшилт явагдаж, өөр хоорондоо ойртож, өндөрсөж байна. Түлхүүр үг: тохролтот хагарал, эсрэг тохролтот хагарал, Таван загийн хоолой, Дунд голын хоолой

Evaluation of Mechanical and Thermal Stresses in Polymer Gear Teeth through Simulation Approach

One way to achieve lightweight and lubricant-free drive train is, among others, to convert conventional steel to polymer composite materials. This paper describes a part of this endeavor by taking a spur gear pair as a study object. One of the steel gear wheel is replaced with three different materials including Victrex PEEK 650G, Victrex PEEK 650CA30 and Luvocom PEEK 1105-8165 while keeping the gear geometry unchanged. Mechanical stresses and thermal properties are two major criteria for material selection at this stage. Therefore carbon fiber filled PEEK (Victrex PEEK 650CA30) and PEEK filled with thermal conductive minerals (Luvocom 1105-8165) are chosen to benchmark each of the criterion. The evaluation is done by modeling the gear mesh and analyzing the contact forces and heat generated in the gear tooth. The results show surface temperature on the tooth flanks, root tensional stress and contact pressure during the tooth mesh. The work suggests a guideline of materials selection. Depending on actual application a compromisation between mechanical and thermal properties often needs to be considered within the tolerance boundary in order to obtain optimized results. This work only deals with material selection. Gear design such as optimization of tooth geometry for polymer gears is out of the scope of this study and will not be discussed.

Tectono-sedimentary model for the evolution of the Silves Group (Triassic, Lusitanian basin, Portugal)

At the beginning of the Alpine cycle, the breakup of Pangea lead to the early stages of the North Atlantic opening. In the western Iberian sector of the European margin, the Lusitanian basin starts to evolve bordered eastwards by inherited reliefs from the late episodes of the Variscan orogeny. The base unit, the Silves Group, considered not earlier than the Carnian, is mainly siliciclastic and predominantly formed by arcosarenites to feldspar litarenites, coarse to very coarse-grained (wackes) and pebbly, where the sediment architecture denotes organizations in continental (Conraria, Penela and Castelo Viegas Formations) environments. A first marine episode (Isocyprina Beds of Pereiros Fm.) marks a significant change within the sedimentary record; the uppermost part corresponds to intertidal transitional environments (sabkha). New and detailed field work of sedimentological and structural nature that has been carried out in recent exposures from the type-region of Coimbra-Penela enabled us to make significant observations and to improve data collection. This allowed a full reinterpretation of the paleotectonic and paleogeographical conditions under which the Silves Group and, consequently, the eastern border of the Lusitanian basin, evolved. This study carried out in the type-region also allowed a better understanding of its sequential organization. All units are unconformity bounded by strong influxes of coarse siliciclastics from the Iberian meseta. One of those unconformities (D2b) is an angular unconformity with cartographic expression. Tectonic reconstructions were possible to make after a detailed structural analysis of normal synsedimentary faults. Regional comparisons with Eastern Iberian basins that evolved since Permian times are also discussed. We conclude that the lower red siliciclastic units are older than has been considered until now. Those units were formed in a previous tensional stress pattern of tardi-Variscan affinities, related to megashear dextral kinematics of Permian-Triassic age. We propose that units below D2b unconformity can record a Proto-Lusitanian basin; the Lusitanian basin is younger and evolved mainly after the Triassic-Jurassic limit (Castelo Viegas Fm.) within an E-W extensional context related to Atlantic type basins.

Tracing the 1271–1246 Ma Central Scandinavian Dolerite Group mafic magmatism in Fennoscandia: U–Pb baddeleyite and Hf isotope data on the Moslätt and Børgefjell dolerites

Between 1271 and 1246 Ma, dolerite dykes and sills of the Central Scandinavian Dolerite Group intruded into the Fennoscandian Shield during three distinct magmatic pulses. They are distributed around five large magmatic complexes extending from Sweden to western Finland and record large-scale intracratonic tensional stress. Coeval plutonism is observed in the westernmost terrane of the Sveconorwegian orogen in southern Norway, but differs in the sense of a bimodal character and uncertain Fennoscandian ancestry of the host terrane. We report a U–Pb baddeleyite age of 1269 ± 12 Ma for a gabbronoritic member of an E-trending set of dykes, called the Moslätt Dolerites, near Lake Vättern in southern Sweden, much farther to the south than any previously known Central Scandinavian Dolerite Group rock. A similar age of approximately 1275 Ma is obtained for a meta-dolerite sheet in the Børgefjell basement window in the Scandinavian Caledonides in Mid-Norway. The initial epsilon-Hf values for these two dykes are +3.9 and +10.1, respectively, and correspond to the range of values for other occurrences of the Central Scandinavian Dolerite Group (+4.7 to +10.3). They add to the evidence that the Central Scandinavian Dolerite Group is characterized by more positive epsilon values (depleted source) than other mafic Proterozoic suites in Fennoscandia. These results extend the distribution of c. 1270–1245 Ma mafic magmatism in Fennoscandia, particularly when accounting for significant Caledonian shortening. The Central Scandinavian Dolerite Group and coeval bimodal magmatism in S Norway may represent distal magmatic events related to a Mesoproterozoic subduction along the western margin of Fennoscandia rather than hotspot (mantle plume) activity as previously suggested.

Myosin II Is Essential for the Spatiotemporal Organization of Traction Forces during Cell Motility

Amoeboid motility requires spatiotemporal coordination of biochemical pathways regulating force generation and consists of the quasi-periodic repetition of a motility cycle driven by actin polymerization and actomyosin contraction. Using new analytical tools and statistical methods, we provide, for the first time, a statistically significant quantification of the spatial distribution of the traction forces generated at each phase of the cycle (protrusion, contraction, retraction, and relaxation). We show that cells are constantly under tensional stress and that wild-type cells develop two opposing “pole” forces pulling the front and back toward the center whose strength is modulated up and down periodically in each cycle. We demonstrate that nonmuscular myosin II complex (MyoII) cross-linking and motor functions have different roles in controlling the spatiotemporal distribution of traction forces, the changes in cell shape, and the duration of all the phases. We show that the time required to complete each phase is dramatically increased in cells with altered MyoII motor function, demonstrating that it is required not only for contraction but also for protrusion. Concomitant loss of MyoII actin cross-linking leads to a force redistribution throughout the cell perimeter pulling inward toward the center. However, it does not reduce significantly the magnitude of the traction forces, uncovering a non–MyoII-mediated mechanism for the contractility of the cell.

Stress Testing of Individual Steel Strands in a Multiple-Cable Single Borehole Anchorage for Geotechnical Engineering

Multiple-cable single borehole anchorages are widely used in China, accepted and regarded as a very effective method for slope protection, landslide remediation and foundation ditch support. This paper presents a new method for testing tensional stresses of individual steel strands within anchor cables in single boreholes. A rig has been designed to permit testing of cables within a single borehole, including two special features: a metal plate that distributes tension between strands of a cable and a sensing device that measures the stress in each individual strand. The feasibility of the method has been demonstrated by an in situ tensional stress test on anchor cables at a landslide remediation site that successfully measured the forces on individual steel strands fastened to different anchorage segments within a borehole. The steel cable strands displayed nonlinear extension characteristics; and the length of anchorage segments and grout strength met design criteria. The results confirm that this design of anchorage is satisfactory and can provide valuable data for future design and construction.

Large-scale slope failure and active erosion occurring in the southwest Ryukyu fore-arc area

The southwestern Ryukyu area east of Taiwan Island is an arcuate boundary between Philippine Sea Plate and Eurasian Plate. The topographic features in the area are characterised by (1) a large-scale amphitheatre off Ishigaki Island, just on the estimated epicentre of the tsunamigenic earthquake in 1771, (2) lots of deep sea canyons located north of the amphitheatre, (3) 15–20 km wide fore-arc basin, (4) 15–20 km wide flat plane in the axial area of the trench, (5) E-W trending half grabens located on the fore-arc area, etc., which were revealed by several recent topographic survey expeditions. The diving survey by SHINKAI6500 in the fore-arc area on a spur located 120 km south of Ishigaki Island was carried out in 1992. The site is characterised dominantly by rough topography consisting of a series of steep slopes and escarpments. A part of the surface is eroded due to the weight of the sediment itself and consequently the basement layer is exposed. The site was covered with suspended particles during the diving, due to the present surface sliding and erosion. The same site was resurveyed in 1997 by ROV KAIKO, which confirmed the continuous slope failure taking place in the site. Another example that was observed by KAIKO expedition in 1997 is a largescale mud block on the southward dipping slope 80 km south of Ishigaki Island. This is apparently derived from the shallower part of the steep slope on the southern edge of the fan deposit south of Ishigaki Island. The topographic features suggest N-S or NE-SW tensional stress over the whole study area. In this sense, the relative motion between the two plates in this area is oblique to the plate boundary. So, the seaward migration of the plate boundary may occur due to the gravitational instability at the boundary of the two different lithospheric structures. This is evidenced by a lack of accretionary sediment on the fore-arc and the mechanism of a recent earthquake which occurred on 3 May 1998 in the Philippine Sea Plate 250 km SSE of Ishigaki Island.