Main Plate Research Articles

Continental breakup and UHP rock exhumation in action: GPS results from the Woodlark Rift, Papua New Guinea

AbstractWe show results from a network of campaign Global Positioning System (GPS) sites in the Woodlark Rift, southeastern Papua New Guinea, in a transition from seafloor spreading to continental rifting. GPS velocities indicate anticlockwise rotation (at 2–2.7°/Myr, relative to Australia) of crustal blocks north of the rift, producing 10–15 mm/yr of extension in the continental rift, increasing to 20–40 mm/yr of seafloor spreading at the Woodlark Spreading Center. Extension in the continental rift is distributed among multiple structures. These data demonstrate that low‐angle normal faults in the continents, such as the Mai'iu Fault, can slip at high rates nearing 10 mm/yr. Extensional deformation observed in the D'Entrecasteaux Islands, the site of the world's only actively exhuming Ultra‐High Pressure (UHP) rock terrane, supports the idea that extensional processes play a critical role in UHP rock exhumation. GPS data do not require significant interseismic coupling on faults in the region, suggesting that much of the deformation may be aseismic. Westward transfer of deformation from the Woodlark Spreading Center to the main plate boundary fault in the continental rift (the Mai'iu fault) is accommodated by clockwise rotation of a tectonic block beneath Goodenough Bay, and by dextral strike slip on transfer faults within (and surrounding) Normanby Island. Contemporary extension rates in the Woodlark Spreading Center are 30–50% slower than those from seafloor spreading‐derived magnetic anomalies. The 0.5 Ma to present seafloor spreading estimates for the Woodlark Basin may be overestimated, and a reevaluation of these data in the context of the GPS rates is warranted.

Local–global mode interaction in stringer-stiffened plates

A recently developed nonlinear analytical model for axially loaded thin-walled stringer-stiffened plates based on variational principles is extended to include local buckling of the main plate. Interaction between the weakly stable global buckling mode and the strongly stable local buckling mode is highlighted. Highly unstable post-buckling behaviour and a progressively changing wavelength in the local buckling mode profile are observed under increasing compressive deformation. The analytical model is compared against both physical experiments from the literature and finite element analysis conducted in the commercial code Abaqus; excellent agreement is found both in terms of the mechanical response and the predicted deflections.

Trapped vortices in multiply connected domains

This paper details a generalized method to, within some numerical tolerance, compute vortex equilibria in the presence of many obstacles. Given a conformal mapping between a pre-image circular domain and the physical domain, stationary conditions for the point vortices and the desired Kutta conditions are constructed and then solved using a Brownian Ratchets scheme. The method is applied to a Kasper Wing (three plate) configuration and results are compared to those of a single plate. The lift experienced by the main plate is seen to be sensitive to the placement of the two additional plates but their presence can be force enhancing for certain configurations.

Cellular buckling in stiffened plates

An analytical model based on variational principles for a thin-walled stiffened plate subjected to axial compression is presented. A system of nonlinear differential and integral equations is derived and solved using numerical continuation. The results show that the system is susceptible to highly unstable local–global mode interaction after an initial instability is triggered. Moreover, snap-backs in the response showing sequential destabilization and restabilization, known as cellular buckling or snaking, arise. The analytical model is compared with static finite element (FE) models for joint conditions between the stiffener and the main plate that have significant rotational restraint. However, it is known from previous studies that the behaviour, where the same joint is insignificantly restrained rotationally, is captured better by an analytical approach than by standard FE methods; the latter being unable to capture cellular buckling behaviour even though the phenomenon is clearly observed in laboratory experiments.

Experimental Study on Effect of Vibratory Flap Position on Dynamic Response of Clamped Rectangular Plate with Cut-Out

In structural applications, plates with cut-out or holes are commonly used. The structure will deteriorate dynamically due to presence of cut-out and experiences amplification in vibrations. This paper presents an experimental study on effect of position of vibratory flap on dynamic response of a clamped rectangular plate with cut-out subjected to harmonic excitation. Vibratory flap is an auxiliary plate attached on the main plate as a cantilever plate and acts as a dynamic vibration absorber, which is used to reduce the vibration of the plate at first and second frequencies. Investigation has been carried out for different combinations of flap location and orientation through experimental sine sweep test. From the test it is found that, there is an optimum position where vibration suppression is more effective with improved dynamic response of the plate with cut-out in the presence of flap. The experimental results have shown good agreement with the published finite element analysis results.

구조 응력 기법을 적용한 필릿 용접부 두께 지수 산정에 관한 연구

In this study, non-load-carrying fillet welded joints fabricated using EH grade-steel are evaluated with the structural stress approach. The thickness effect was investigated by a study on welded steel joints with thickness ranging from 25 to 80mm. As-welded joint for main plate thickness of 25 to 80mm, the fatigue strength is reduced gradually. On the other hand, in case of main plate thickness of 25 to 80mm, the structural stress concentration factor increases gradually. As a result, for structural stress approach, thickness effect is not required for correction. Based on these results, a new evaluation fillet welded joint for fatigue design purposes has been proposed FAT 125.

종방향 면내 압축하중 하의 세장한 선박 이중판 하이브리드 설계시스템 구축

In view of the importance of material reduction and rational structural design due to the rapid increase in oil and steel prices, an optimized structural hybrid design system for the doubler plate of a ship's hull structure was developed. A direct design process by a structural designer was added to this developed optimized system to increase the design efficiency and provide a way of directly inserting a designer's decisions into the design system process. As the first step of the doubler design system development, the design formulas used in doubler design system were introduced. Based on the introduction of influence coefficients <TEX>$K_{t_c}$</TEX> <TEX>$K_{t_d}$</TEX>, <TEX>$K_{b_d}$</TEX> and <TEX>$K_{a_d}$</TEX> according to the variations in the doubler length, breadth, doubler thickness, and average corrosion thickness of the main plate, the design formulas for an equivalent plate thickness were developed, and a hybrid design system using these formulas was suggested for the slender doubler plate of a ship structure subjected to a longitudinal in-plane compression load. By using this developed design system, a more rational doubler plate design can be expected considering the efficient reinforcement of the plate members of ship structures. Additionally, a more detailed structural analysis through local strength evaluations will be performed to verify the efficiency of the optimum structural design for the doubler plate.

수치해석을 이용한 토글식 100톤 사출성형기의 중량 개선에 관한 연구

Nowadays, three-dimensional computer added design(3D CAD) tool are widely and actively used for design of mechanical machine. Because using the tool is more effective to understand design concept and to collaborate with other operation than using two-dimensional design tool. In this study, the 3D CAD tool which is called I-DEAS was applied for three-dimensional modeling of main parts and assembling of modeled parts for identification the entire shape of a injection molding machine. In addition, a study was also performed regarding reduction for the weight of main plates for saving production cost and energy in the machine. A finite element method(FEM) program in I-DEAS tool was used for the improvement study. First, the current main plates were structural analysed and then the plate deformations, weak regions and stress distributions were graped. By the FEM results, the 2nd improved designing of the plates was conducted such as reinforcement or slimming of the plate wall thickness. The 2nd structural FEM was performed for verification of the redesigned plates and then the FEM results were compared with the 1st FEM`s result. The weight of the main plates were averagely reduced approximately 3 - 7%. By these results, it was seemed that the improved plates have a useful availability.

Structural Design and Artistic Expression of Landscape Multi-Span Arch Footbridge

In order to perfectly make the bridge function, structural style, architectural art modeling with the surrounding environment, this paper, based on the design of landscape five-span arch footbridge, studies the span arrangement, structural style, building materials, railing shape, ornament style and color, and lamplight illumination of the bridge considering the factors such as hydrology, geology, surrounding environment (e.g. buildings and park), traffic flow and entire urban planning. To reduce the stress of main arch and the horizontal thrust of substructure, the new structure of T-frame with sloped plate was put forward to bear the deck loads with the assistance of main plate arch. The thin concrete walls were cast on the top sides of the main plate arch, which were decorated by fine stone with the modern decoration construction technology. The white marble railings present lively morphology with carved lotus and pomegranate on the column cap, and many kinds of flowers on the panels. The spotlights make dramatic night sense for the bridge. Therefore, the landscape footbridge in the classical arch graceful shape was constructed by the modern building material and the optimized reinforced concrete structure, which presents the unity and coordination of structural design and artistic expression.

Size-dependent pull-in instability of torsional nano-actuator

It is well established that the mechanical behavior of ultra-small elements is size-dependent. In this paper, strain gradient continuum theory is applied for modeling the size-dependent pull-in instability of torsional nano-actuator. An actuator with a general hexagonal shape main plate is considered. The governing equation of the actuator is derived taking the effect of electrostatic and Casimir forces into account. Variation of the tilt angle as a function of the applied voltage is calculated. Moreover, the pull-in voltage and pull-in angle of the actuator are determined. Results show that when the thickness of the torsional beam is comparable with the intrinsic material length scales, size effect can substantially increase the instability voltage and angle of the rotational actuator. Moreover, the effect of the Casimir force on the size-dependent pull-in instability of the torsional actuator is discussed. Interestingly, the proposed model is able to predict the experimental results more accurately than the previous classic models and reduce the gap between previous theories and experimental measurements.

Experimental Study of Flat Format Multichannel Triggered Rail Spark Gap

This paper is concerned with the development and testing of a compact flat format multichannel electrically triggered rail spark gap. It is tested for multichannel discharge under atmosphere for high reliability. Multichannel discharge rail spark gaps can be developed using laser trigger or fast rising trigger voltage pulse . The extra volume and weight added by laser or fast triggering circuits limit the use in pulse power applications. An electrically multitriggered low-inductance spark gap is developed. It is used as a multichannel low-inductance discharging element in a fast rising high-current generation system. The trigger of such rail gap is realized using the set of round copper pins similar to single trigger pin in a field distortion spark gap. In parenthesis, five different trigger pins are located in main trigger plate and these are isolated with high impedance. Therefore, five different trigger signals are generated with time difference of tens of nanoseconds. The major material erosion at five points of both stainless steel main electrodes confirms the multichanneling discharge. The main gap spacing in this switch is 4 mm and the trigger is located close to the ground electrode for reducing the delay time and jitter in delay time. This paper shows the trigger circuit design, main gap voltage, and trigger voltage effect on the closing of the spark gap and picture of electrodes after use.

Crack of a helicopter main rotor actuator attachment: failure analysis and lessons learned

Crack of a helicopter main rotor actuator attachment: failure analysis and lessons learned

Characteristics of a tsunamigenic megasplay fault in the Nankai Trough

Slip on the shallow part of a megasplay fault that is an out‐of‐sequence thrust and branch of the main subduction plate boundary can cause devastating tsunamis after earthquakes. We analyzed the three‐dimensional geometry, including dip amount and azimuths, roughness distributions, and thickness variations, of the shallow part of a megasplay fault in the Nankai Trough using a three‐dimensional seismic data set. The fault is divided into three zones based on its geometry: thick, smooth, and simply convex in the east; complexly curved in the middle; and thin and kinked in the west. Results of scientific drilling indicate that the eastern region of the fault is most active, and local heterogeneities in fault geometry, including roughness and thickness, may control the slip on this part of the fault. The present findings can be used to evaluate the risk of future tsunamis arising from movement on shallow thrust faults at subduction margins.

Tethys tectonic evolution and its bearing on the distribution of important mineral deposits in the Sanjiang region, SW China

The Sanjiang region in SE Tibet Plateau and NW Yunnan is known to have formed by amalgamation of Gondwana-derived continental blocks and arc terranes as a result of oceanic subduction followed by continental collision from Paleozoic to Mesozoic. In this paper we provide a synthesis of tectonic evolution, magmatism and metallogeny in the region based on data from literatures. Early Paleozoic ophiolites (473–439Ma) in the Changning–Menglian belt indicate the existence of a Proto-Tethys ocean in this region. Two episodes of subduction-related magmatism in the early-Paleozoic, one occurred in the Baoshan and Tengchong blocks at 502–455Ma and the other occurred in the Simao block at 421–401Ma, are regarded as evidence for two different events of subduction of the Proto-Tethys ocean at different locations. The Proto-Tethys was succeeded in early-Devonian by the Paleo-Tethys which comprised the main ocean and three branches: Ailaoshan, Jinshajiang and Garzê–Litang. The Changning–Menglian main ocean existed from middle-Devonian to middle-Triassic. The remnants of the oceanic crust are preserved in a few places in the Longmu Tso–Shuanghu suture as well as in the Changning–Menglian ophiolite belt. The eastward subduction of the main oceanic plate from early-Permian to early-Triassic formed a prominent arc terrane stretching >1500km from Yunnan to eastern Tibet. From the waning stage of subduction to post-subduction, numerous S-type granite plutons with ages varying between 230 and 219Ma, such as the Lincang batholith in Yunnan were emplaced at or close to the suture. This event produced several hydrothermal W–Sn deposits in the region. The tectonic evolution and associated magmatism of the Jinshajiang and Ailaoshan branch oceans are generally comparable to those of the main ocean. However, the branch oceans were subducted westward instead. The Garzê–Litang branch ocean also underwent westward subduction from middle-Devonian to late-Triassic. Arc-related high Sr/Y porphyry intrusions and associated porphyry-skarn Cu–Mo–Au deposits are common in the Jinshajiang–Ailaoshan region, especially in the Yidun arc which formed prior to Jurassic. The VMS deposits in the Sanjiang region formed in diverse tectonic settings including middle-Silurian back-arc basins, Carboniferous oceanic islands, Paleozoic subduction zones and Triassic post-subduction rifting environments. The Mesozoic and early-Cenozoic evolution of the Baoshan and Tengchong blocks was largely influenced by eastward oceanic subduction of the Meso- and Neo-Tethys from late-Permian to middle-Cretaceous and from late-Cretaceous to ~50Ma, respectively. Abundant early-Cretaceous granitoids and associated skarn-type Pb–Zn and Sn–Fe deposits in the Baoshan and Tengchong blocks were produced in the background of the Shan boundary oceanic slab subduction to the west and the break-off of the Nujiang-Bitu oceanic slab to the north. The subduction of the Neo-Tethys oceanic plate beneath the Tengchong block from Late Cretaceous to Paleogene formed abundant S-type granitoids and many skarn-type and greisen-type Sn–W deposits. Granitoids formed at 105 to 81Ma and contemporaneous hydrothermal W, Mo, Ag and Au deposits, which temporally coincided with the subduction of the Neo-Tethys, are common in the Yidun arc terrane.

Lamb wave band gaps in a homogenous plate with periodic Gaussian surfaces

The Lamb wave band structure of a one-dimensional thin plate with periodic Gaussian surfaces is calculated based on the eigen-mode matching theory (EMMT) method. The finite element method is also employed to calculate the transmission power spectra and the band structure, which are both in good agreement with the results of the EMMT method. In contrast with the straight stubs, the low-frequency band gap of the system with the Gaussian surfaces is wider, when the Gaussian domain's height and area are equal to those of the stub, and the two systems' main plate size and materials are the same. This can be confirmed by the ‘spring–mass' model, which can be used to estimate the resonant frequency. We also investigate the effects of the geometrical parameters on band structure, including the height of the Gaussian domain, the plate thickness and the filling fraction. The results suggest that the band gaps have a close relevance to them.

조선해양 구조물 주판의 Butt welding joint 수축에 관한 연구

This paper examines the characteristics of butt welding joint shrinkage for shipbuilding and marine structures main plate. The shrinkage strain of butt welding joint which is caused by the process of heat input and cooling, results in the difference between dimensions of the actual parent metal and the dimensions of design. This, in turn, leads to poor quality in the production of ship blocks and reworking through period of correction brings about impediment on improvement of productivity. Through experiments on butt welding joint`s shrinkage strain on large structures main plate, the deformation of welding residual stress in the form of I, Y, V was obtained. In addition, the results of experiments indicate that there is limited range of shrinkage in the range of 1 ~ 2 mm in 11t ~ 21.5t thickness and the effect of heat transfer of weld appears to be limited within 1000mm based on one side of seam line so there was limited impact of weight of parent metal on the shrinkage. Finally, it has been learned that Shrinkage margin needs to be applied differently based on groove phenomenon in the design phase in order to minimize shrinkage.

The Arabian Plate: unique fit of the earth's surface jig saw puzzle

The Arabian Plate is important and unique in many ways. The worker wants to highlight the important features characterizing the Arabian Plate. It is a unique fit of the earth's surface jig saw puzzle, different than all other lithospheric plates. It has the three known main tectonic plate boundaries, divergent, convergent and conservative ones. These boundaries are the Red Sea and Gulf of Aden, Zagros-Taurus and Dead Sea, respectively. It has three main well-defined and sharp plate boundaries, and it is surrounded by three major plates, African, Eurasian and Indian plates. The Red Sea and Gulf of Aden form the divergent boundary and spreading center. The Dead Sea Transform Fault (the Gulf of Aqaba Transform Fault) represents the conservative boundary and transform fault system. The Zagros-Taurus Thrust (Zagros-Taurus-Bitlis Thrust and Fold Belt) represents the convergent boundary and collision zone. The Arabian Plate incorporates a wide range and variety and subvariety of all three rock types, igneous, metamorphic and sedimentary rocks, this in addition to all kinds of structures. Among these are folding with major fold belts, faulting, foliation, lineation and diapirism. Transform, transcurrent, normal, graben, reverse, thrust faults are all represented one way or another. The tectonics of the Arabian shield, which forms a major part of the Arabian Plate, has long tectonic history prior to the formation of the Red Sea. After the opening and formation of the latter, the tectonics of the Arabian shield became affected and controlled by its tectonics. The Arabian Plate includes the Arabian Platform which has a relatively different setting of tectonics represented by the Central Arabian Graben. The Arabian Plate contains one of the best representative outcropped ophiolite sequences in the world. The Arabian Plate most importantly incorporates most of world oil reserve. Seismic and volcanic activities are also manifested and affected many areas in the Arabian Plate.

Adakites in the Truong Son and Loei fold belts, Thailand and Laos: Genesis and implications for geodynamics and metallogeny

LA-ICP-MS U–Pb zircon dating reveals that the Phu Kham adakites in the Truong Son Belt were emplaced during the Late Carboniferous (ca. 306 to 304Ma), whereas the Puthep 1 (PUT 1) adakites in the Loei Fold Belt were formed during the Middle Triassic (ca. 244 to 241Ma). These rock formation ages are largely coeval to Re–Os molybdenite ages (Phu Kham: ca. 304Ma; PUT 1: ca. 246Ma), suggesting close temporal links between adakite formation and copper–gold mineralization. New geochemical results show that the Phu Kham and PUT 1 adakites are characterized by low HREE and Y contents, but elevated LREE, Sr, Sr/Y, and La/Yb values. In addition, the two adakites have relatively high 143Nd/144Nd ratios (0.512648 to 0.512719), Mg# (Phu Kham: 37–68; PUT 1: 40–65), and Cr and Ni contents. These results are best interpreted as representing slab melts that have interacted with supra-subduction zone mantle wedge during ascent. Tectonically, the Phu Kham and PUT 1 adakites were most likely formed during the initiation of subduction of the Ailaoshan–Song Ma and the Main Paleo-Tethys ocean plates respectively. Close temporal relations between the adakite formation and the copper–gold mineralization suggest strong genetic links between the two in the mainland SE Asia region.

반도체 패키징용 기계식 프레스의 최적설계에 관한 연구

Mechanical molding press which is used for transformation process during semiconductor manufacturing process has structural deformations by pressure. If these deformations have over limit range, life of the press itself can be reduced and it will be exerted on a bad effect for quality of the semiconductor. In this research, the main plates and links of a press are analyzed in relation to the structural deformations caused by pressure excluding thermal deformations. After modifying the modeling, the analysis is performed again to determine optimal design of the press, and this design is introduced to ensure that most of the stresses on the main plates are within safe allowable limits. As a result, an optimal design method for the structure is investigated to produce the desired pressure even when the size of the main structure is minimized.

Lyon bracing in adolescent females with idiopathic scoliosis: assessment of results according to the SRS committee on bracing and nonoperative management standardization criteria

Background The Lyon brace, devised by Stagnara in 1950, is commonly prescribed in many European countries, and is based on the three-point pressure system. The Lyon brace also applies derotational forces to the spine, with the main thoracic plate pushing the hump from the posterior convexity toward the anterior concavity of the scoliotic curve. Lyon bracing is considered to be an effective means for conservative treatment of scoliosis.