Buckling behavior of laminated composite cylinders under external hydrostatic pressure

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Zhun Li ◽  
Guang Pan ◽  
KeChun Shen
Keyword(s):  
Slenderness Ratio ◽  
Golden Section ◽  
Laminated Composite ◽  
Content Type ◽  
Buckling Behavior ◽  
Golden Section Method ◽  
Helical Winding ◽  
Initial Geometric Imperfections ◽  
Winding Angle ◽  
Composite Cylinders

PurposeThe objective of this paper is to investigate numerically the buckling behavior of submersible composite cylinders.Design/methodology/approachBy means of FEM and golden section method, the search of hoop winding layers, longitudinal winding layers and helical winding layers are studied to optimize the buckling pressure. Considering the mid-strengthening cylinder, the size and distribution of stiffeners are studied systematically.FindingsThe results show that laying the hoop winding layers in the two outer sidewalls and the longitudinal winding layers in the middle of the shell is helpful to increase the buckling pressure, and the optimal helical winding angle changes with slenderness ratio.Originality/valueFor mid-strengthening cylinder, the effect of helical winding angle of stiffener on buckling pressure becomes weak gradually with the increase of stiffener thickness. With the increasing of the spacing between stiffeners, the buckling pressure increases first and decreases later. What is more, the mid-strengthening cylinder is less sensitive to the initial geometric imperfections than unstiffened shells.

Appraisal of Allowable Loads by Simplified Rules

1986 ◽  
Vol 108 (2) ◽  
pp. 131-137
Author(s):  
D. Moulin
Keyword(s):  
Experimental Investigation ◽  
Plastic Region ◽  
Thin Structures ◽  
Geometric Imperfections ◽  
Buckling Behavior ◽  
Simplified Method ◽  
Post Buckling ◽  
Initial Geometric Imperfections ◽  
Fast Breeder Reactors ◽  
Breeder Reactors

This paper presents a simplified method to analyze the buckling of thin structures like those of Liquid Metal Fast Breeder Reactors (LMFBR). The method is very similar to those used for the buckling of beams and columns with initial geometric imperfections, buckling in the plastic region. Special attention is paid to the strain hardening of material involved and to possible unstable post-buckling behavior. The analytical method uses elastic calculations and diagrams that account for various initial geometric defects. An application of the method is given. A comparison is made with an experimental investigation concerning a representative LMFBR component.

ON THE ACCELERATION OF OPTIMIZATION METHODS FOR THE PROBLEM OF SYNTHESIS OF MULTILAYER OPTICAL COATINGS

2021 ◽  
Vol 6 ◽  
pp. 13-26
Author(s):  
Alexander Mitsa ◽  
◽  
Petr Stetsyuk ◽  
Alexander Levchuk ◽  
Vasily Petsko ◽  
...  
Keyword(s):  
Objective Function ◽  
Golden Section ◽  
Optical Coatings ◽  
Generalized Gradient ◽  
Arithmetic Operations ◽  
Section Method ◽  
Suffix Arrays ◽  
Multidimensional Search ◽  
Golden Section Method ◽  
Speed Up

Five ways to speed up the multidimensional search in order to solve the problem of synthesis of multilayer optical coatings by using the methods of zero and first orders have been considered. The first way is to use an analytical derivative for the target quality function of the multilayer coating. It allows us to calculate accurately (within the computer arithmetic) the value of the gradient of a smooth objective function and generalized gradient of a non-smooth objective one. The first way requires the same number of arithmetic operations as well as finite-difference methods of calculating the gradient and the generalized gradient. The second way is to use a speedy finding of the objective function gradient using the prefix- and suffix-arrays in the analytical method of calculating the gradient. This technique allows us to reduce the number of arithmetic operations thrice for large-scale problems. The third way is the use of tabulating the values of trigonometric functions to calculate the characteristic matrices. This technique reduces the execution time of multiplication operations of characteristic matrices ten times depending on the computer’s specifications. For some computer architectures, this advantage is more than 140 times. The fourth method is the use of the golden section method for the one-dimensional optimization in the problems of synthesis of optical coatings. In particular, when solving one partial problem it is shown that the ternary search method requires approximately 40% more time than the golden section method. The fifth way is to use the effective implementation of multiplication of two matrices. It lies in changing the order of the second and third cycles for the well-known method of multiplying two matrices and fixing in a common variable value of the element of the first matrix. This allows us to speed up significantly the multiplication operation of two matrices. For matrices having 1000 x 1000 dimension the acceleration is from 2 to 15 times, depending on the computer's specifications.

Focusing of Scattering Light by Improved Feedback Wavefront Shaping Technique Based on Golden Section Method

2017 ◽  
Vol 37 (6) ◽  
pp. 0626005
Author(s):  
胡显声 Hu Xiansheng ◽  
蒲继雄 Pu Jixiong ◽  
冀旋旋 Ji Xuanxuan ◽  
陈子阳 Chen Ziyang
Keyword(s):  
Golden Section ◽  
Section Method ◽  
Shaping Technique ◽  
Golden Section Method ◽  
Wavefront Shaping ◽  
Scattering Light

scholarly journals 3D Numerical Modeling of Laser Assisted Tape Winding Process of Composite Pressure Vessels and Pipes—Effect of Winding Angle, Mandrel Curvature and Tape Width

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2449 ◽  
Author(s):  
Amin Zaami ◽  
Ismet Baran ◽  
Ton C. Bor ◽  
Remko Akkerman
Keyword(s):  
Temperature Distribution ◽  
Bonding Temperature ◽  
Considerable Effect ◽  
Pressure Vessels ◽  
Process Temperature ◽  
Thermoplastic Composites ◽  
Transfer Model ◽  
3D Numerical Modeling ◽  
Helical Winding ◽  
Winding Angle

Advanced thermoplastic composites manufacturing using laser assisted tape placement or winding (LATP/LATW) is a challenging task as monitoring and predicting nip point (bonding) temperature are difficult especially on curved surfaces. A comprehensive numerical analysis of the heat flux and temperature distribution near the nip point is carried out in this paper for helical winding of fiber reinforced thermoplastic tapes on a cylindrically shaped mandrel. An optical ray-tracing technique is coupled with a numerical heat transfer model in the process simulation tool. The developed optical-thermal model predictions were compared with experimental data available in literature to validate its effectiveness. The influences of winding/placement angle, mandrel curvature and tape width on the incident angles, the laser absorbed intensity, and the process temperature distribution are studied extensively using the validated model. Winding/placement angle has a considerable effect on the temperature distribution. Increase in winding angle results in a higher temperature for tape due to more reflections coming from the substrate. On the other hand, substrate temperature decreases as the winding angle increases due to a decrease in the laser incident angles based on the local surface curvature. An increase in mandrel curvature results in higher nip point temperatures for substrate and lower one for tape. Different mandrel sizes for 90 ° placement path do not have a strong effect on the substrate process temperature as for other winding angles because of less curvature change of the corresponding irradiated area. Tape width causes local temperature variations at the edges of the tape/substrate. In order to obtain the desired process temeprature during LATW or LATP processes, the laser intensity distribution on the tape and substrate surfaces should be regulated.

scholarly journals Structural reliability and its sensitivity analysis based on the saddlepoint approximation-line sampling method by dichotomy of golden section

2019 ◽  
Vol 39 (1) ◽  
pp. 11-20
Author(s):  
Ganqing Zhang ◽  
Yanghui Xiang ◽  
Huixin Guo ◽  
Yonghong Nie
Keyword(s):  
Failure Probability ◽  
Structural Reliability ◽  
Golden Section ◽  
Saddlepoint Approximation ◽  
International Study ◽  
Normal Variable ◽  
Line Sampling ◽  
Golden Section Method ◽  
Variable Space ◽  
Solution Efficiency

In order to solve the structural reliability and its sensitivity of the implicit nonlinear performance function (PF) the advantages of the saddlepoint approximation (SA) and line sampling (LS) are merged. Also, the merits of dichotomy and the solution efficiency of the golden section method are combined to propose the saddlepoint approximation-line sampling (SA-LS) method based on the dichotomy of the golden section point. This is complicated and changeable in the non normal variable space, which is a very hot issue of the present international study. For each sample, it is quick to find its zeropoint in PF along the important line sampling direction by the previously mentioned dichotomy so that the structural failure probability can be transformed into the mean of a series linear PFs failure probability, and the reliability sensitivity is just the derivative or partial one of the probability with respect to the relational variables. Examples show that the SA-LS method based on the dichotomy of the golden section point is of high precision and fast velocity in analyzing the structural reliability and sensitivity of the implicit nonlinear PF that are complicated and changeable in the non-normal variable space.

scholarly journals Fault Location of Active Distribution Networks Based on the Golden Section Method

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Haizhu Yang ◽  
Xiangyang Liu ◽  
Yiming Guo ◽  
Peng Zhang
Keyword(s):  
Fault Location ◽  
Golden Section ◽  
Flow Analysis ◽  
Energy Resource ◽  
Distribution Networks ◽  
Load Flow ◽  
Distributed Energy ◽  
Load Flow Analysis ◽  
Distributed Energy Resource ◽  
Golden Section Method

Aiming at the problem of fault location in distribution networks with distributed energy resources (DERs), a fault location method based on the concepts of minimum fault reactance and golden section is proposed in this paper. Considering the influence of distributed energy resource supply on fault point current in distribution networks, an improved trapezoidal iteration method is proposed for load flow analysis and fault current calculation. This method only needs to measure the synchronous current of the distributed energy resource and does not need to measure the voltage information. Therefore, the investment in equipment is reduced. Validation is made using the IEEE 34-node test feeder. The simulation results show that the method is suitable for fault location of distribution networks with multiple distributed generators. This method can accurately locate the faults of the active distribution network under different conditions.

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