Papers by Keyword: Mechanics

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Authors: Justin O. Karl, Andrew T. Copeland, Amy K. Besio
Abstract: The behavior of parts subjected to simultaneous thermal and mechanical fatigue loads is an area of research that carries great significance in the power generation, petrochemical, and aerospace industries. Machinery with expensive components undergo varying applications of force while exposed to variable temperature working fluids. An example case is found in steam turbines, which subject stainless steel blades to cyclic loads from rotation as well as the passing of heated gases. Accurate service life prediction is especially challenging due to the thermo-mechanical loading being present on the complex geometric profile of the blades. This research puts forth a method for determining crack initiation lifetimes in variably-notched type 304 austenitic stainless steel specimens subjected to differing fatigue and thermo-mechanical fatigue conditions. A base analytical model and genetic algorithm were used to develop phenomenology-informed predictions that fall within a factor of two of the actual crack initiation times.
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Authors: Wan Qiang Cheng, Sheng Jie Di, Xue Yong Xu, Gang Song
Abstract: Architectures of fault systems play important role in stability and mechanics of rock mass. While growth mechanism of faults is intrinsic controler for architectures of fault systems. This paper presents a case on faulting in the dam area of an oversized hydropower in Southwestern China. The faults in this area are mostly strike-slip faults with shallow brittle deformation characters, extending tens to hundreds of meters. These faults can be divided into four groups which are formed during two generations corresponds to two periods of tectonic events. Growth model of these faults have been built based on geologic and mechanic data. The first generation of faults was formed based on preexisting joints. While the secondary generation emerge only if the existing faults become critically misaligned during rotation of the primary stresses. The criterion laws for formation of secondary faults are suggested. According to the growth model, we can predict placement of secondary faults in space. Conversely, when geometry and space characters of the fault systems are known, we can estimate mechanic parameters and tectonic environments of the rock mass.
883
Authors: Michał Ostaszewski, Franciszek Siemieniako
Abstract: In the article a construction of a laboratory station for determination of angles in three kinematic pairs of human lower limbs exoskeleton is described. The constructed exoskeleton is supposed to support human lower limbs only on plane vertical to ground. In article the results of measurement of movement parameters of walking human lower limbs obtained using the measuring station. Measurement of angular displacement on the station is realized using six angular displacement absolute transducers. The station is also one of the components contained in lower limb exoskeleton being constructed. The measuring construction will be used to identify actuating systems during exoskeleton construction phase.
326
Authors: Min Zheng, Ao Fang, Hong Yan Duan, Ding Fan
Abstract: The gradient calcium phosphate bioceramic coating was produced on titanium alloy substrate by laser cladding. The microstructure, microhardness, fracture toughness, and residual stress of the tatanium-based gradient bioceramic composite coating were investigated. The results show that the microhardness gradually decreases with further depth increasing cross-section. The highest microhardness of the coating and the transition layer is 1544HV and 1160HV, respectively. The fracture toughness KIC is 3.72±0.03 MPa·m1/2 of bioceramic coating and 4.55±0.02 MPa·m1/2 of the transition layer, which is closely resembles the human compact bone. Furthermore, the residual stress gradually decreases from the coating to substrate, which is 221MPa between ceramic layer and the transition layer and 108MPa between the transition layer and substrate. This distribution is conforms to gradient composition design, which reducing harm of the specimen deformation and cracking.
353
Authors: Yu Fei Liu, Zhen Zhen Dong, Wei Zheng Chen, Guang Zhi Li
Abstract: In this paper, combining with the domestic design and application of the snowplow in quality and quantity two aspects, basing on engineering application software ADAMS and CATIA, dynamics for 10t snowplow working device was researched, and the strength of the main stress components was analyzed by finite element method. On the basis of lightweight, strength and structure reasonable design, the snowplow device structure was verified feasibility through the research results. The paper studies could have a certain theoretical reference for the theoretical design and practical application of similar products.
308
Authors: Er Bao Peng, Hong Ge Zhang, Hong Ying Wang
Abstract: To study vibration signals processing mechanics and the analysis method of the numerical control machine. vibration signals analysis method include time and frequent domain analysis: the time domain analysis mainly has the statistical analysis and the correlation function analysis. frequency domain analysis include spectral analysis, cepstrum analysis, data envelopment analysis. vibration signals pretreatment is the most commonly used and effective method on the mechanical device condition monitor and the failure diagnosis.
162
Authors: Zhi Jie Sun
Abstract: To research the mechanics characteristic of support structure of shallow-buried large section loess tunnel with different construction methods, 3D Numerical Simulation is applied and the large-section loess tunnel of highway is taken as an example. Comparing mechanics characteristic of support structure in three types of construction method conditions, the research results show that:The Benching stepping method which caused large surrounding rock deformation can reduce the value of structural performance. While the Both side heading is just opposite.
589
Authors: Syed A.A. Shah, Syed T. Hasan
Abstract: The performance of metal matrix composites (MMCs) depends critically on the quality of the matrix-reinforcement interface. The nature of the interface in turn depends on the processing of the MMCs. At the micro-level, local concentration gradients around the reinforcement are being developed during processing and due to the metal matrix attempting to deform during deformation which can be very different to the nominal conditions. This plays a crucial role in the development of micro-structural events such as segregation and precipitation at the matrix-reinforcement interface. Micro-deformation characteristics of matrix reinforcement interface are modelled using commercial FE software and compared with analytical and experimental data. A method of calculation has been applied to predict the interfacial fracture strength of aluminium silicon carbide (Al-SiC) with 20% Vol fraction. Preliminary results show that the model succeeds in predicting the trends in relation to segregation and intergranular fracture strength behaviour in these materials. The proposed hypothesis will help the design engineers to select and use the materials in structural/load bearing applications. Interfacial strengthening characteristics will in turn give more accurate life predictions of such smart composite systems.
137
Authors: Zhi Qiang Xu
Abstract: The conveyer belt is a major component of the conveyor , whose cost accounted for half of the of the entire cost of the conveyor. The loss of the conveyor is mainly due to the use of friction and wear generated in the process, so study on the friction characteristics is very meaningful. The friction and wear of the conveyor is one of the factors affecting their life. Therefore, conducting applied research on belt conveyors and mechanical analysis becomes increasingly important. In this paper, some qualitative research on the mechanical properties is carried out, starting from the application of the conveyor belt.
218
Authors: Ke Qiu, Feng Luo
Abstract: This paper expresses several quantities of Mechanics that can be solved using eigen value and eigen vector of matrix in a unified expression. It revealed and discussed the mathematical nature of these quantities of Mechanics. The eigen matrix diagonalization method that can be used to easily solve all the eigen values and orthogonal eigen vectors of a matrix is given. This method is liberation from the difficulties of solving these quantities traditionally.
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