Structural Design of Large Aperture Rectangular Mirror for Space Telescope

2012 ◽  
Vol 256-259 ◽  
pp. 855-858
Author(s):  
Zhi Lai Li
Keyword(s):  
Structural Design ◽  
Optical Axis ◽  
Lightweight Design ◽  
Materials Selection ◽  
Support Design ◽  
Element Analysis ◽  
Space Telescope ◽  
First Order ◽  
Large Aperture ◽  
Flexible Support

Structural design of large aperture mirror is one of the key technologies for space telescope development. To meet the requirements of high stiffness, strength and thermal dimensional stability, some factors such as support scheme, materials selection, lightweight design and flexible support design were taken into account. The three supports location of the mirror was determined according to the modal analytical solution. By adjusting the parameters of flexure hinge, influences of gravity, assembly stress and thermal stress on the mirror were reduced obviously. Finite element analysis (FEA) results indicate that the surface accuracy reach to rms10.2nm and 10.8nm under the gravity along optical axis direction and 5°C uniform temperature rise respectively, the fundamental frequency of the mirror component is 268Hz. Dynamics test shows that the first order natural frequency is 256Hz, which shows an error less than 5% compared to FEA results.

Lightweight Vehicle Structural Design with Advanced Steel Grades and Profiles

2015 ◽  
Vol 809-810 ◽  
pp. 1199-1204 ◽  
Author(s):  
Cristian Ulianov ◽  
Ramy Shaltout ◽  
Adrian Ciprian Balan
Keyword(s):  
Structural Design ◽  
Lightweight Design ◽  
Element Analysis ◽  
Lightweight Structures ◽  
Traditional Design ◽  
Design And Manufacturing ◽  
Steel Grades ◽  
Structural Solutions ◽  
Significant Effort

In the recent decades, the vehicle lighweighting problem has been addressed through various methodologies by different researchers and industries. Significant effort has been made recently to develop lightweight structural solutions by employing state-of-the-art and emerging materials, manufacturing processes and technologies. The presented research aimed to investigate the possibility of designing vehicle lightweight structures using advanced steel grades and novel structural profiles developed by industry by integrating smart design and manufacturing solutions. A case study was developed in the presented paper on a freight wagon structure. The structural stress analysis of the new lightweight design has been carried out through Finite Element Analysis (FEA) for validating the proposed solutions. The FEA considered the standard loading scenarios, taking into account both the static and dynamic operational loads, and the results were evaluated against the traditional design of a similar benchmark homologated vehicle. The results demonstrate that novel steel products can be successfully employed for designing sustainable and feasible lightweight vehicle structures.

Research on the Support and Gravitational Deformation of Large Aperture Primary Mirror of Space Telescopes

2012 ◽  
Vol 516 ◽  
pp. 181-185
Author(s):  
Yang Lin Peng ◽  
Yi Fan Dai ◽  
Shan Yong Chen
Keyword(s):  
Body Motion ◽  
Space Telescopes ◽  
Key Factors ◽  
Support Design ◽  
Element Analysis ◽  
Primary Mirror ◽  
Imaging Quality ◽  
Large Aperture ◽  
Support Methods ◽  
Surface Figure

The surface figure of the primary mirror in a large aperture telescope is one of the key factors influencing imaging quality. Space telescopes are used in weightless environments, which is different from the ground environment for optical machining and testing. Therefore the effect of the deformation induced by gravity on the imaging quality is not negligible and the mirror support is to be carefully designed to unload the gravity during the course of machining and testing. In this paper, finite element analysis software is adopted to simulate and compare the deformation induced by gravity of a metre-scale aspheric lightweight primary mirror with different support methods and different working conditions. The results are then imported into MetroPro software supplied by ZYGO Corporation, to remove the tilts and rigid body motion of the mirror and calculate the primary aberrations from the deformation. Finally, sensitivity analysis of support deformation is implemented and the principles of mirror support design are summarized. The research is instructive for design, machining and testing of large aperture mirrors.

Delamination of Laminate Plates

2014 ◽  
Vol 969 ◽  
pp. 97-100 ◽  
Author(s):  
Eva Kormaníková
Keyword(s):  
Finite Element Analysis ◽  
Mixed Mode ◽  
Plate Theory ◽  
Laminate Plate ◽  
Element Analysis ◽  
Interface Elements ◽  
First Order ◽  
Plate Elements ◽  
Interface Modeling ◽  
Shear Deformable

The paper deals with numerical modeling of delamination of laminate plate consists of unidirectional fiber reinforced layers. The methodology adopts the first-order shear laminate plate theory and fracture and contact mechanics. There are described sublaminate modeling and delamination modeling by the help of finite element analysis. With the interface modeling there is calculated the energy release rate along the lamination front. Numerical results are given for mixed mode delamination problems by implementing the method in a 2D finite analysis, which utilizes shear deformable plate elements and interface elements. Numerical example is done by the commercial ANSYS code.

Novel Trapezoidal-Loop Piezoelectric Energy Harvester

2014 ◽  
Vol 672-674 ◽  
pp. 402-406
Author(s):  
Bing Jiang ◽  
Shuai Yuan ◽  
Xiao Hui Xu ◽  
Mao Sheng Ding ◽  
Ye Yuan ◽  
...  
Keyword(s):  
Output Voltage ◽  
Energy Harvester ◽  
Research Field ◽  
Structure Design ◽  
Loop Structure ◽  
Element Analysis ◽  
Resonant Frequencies ◽  
First Order ◽  
Microelectronic Devices ◽  
Piezoelectric Energy

In recent years, piezoelectric energy harvester which can replace the traditional battery supply has become a hot topic in global research field of microelectronic devices. Characteristics of a trapezoidal-loop piezoelectric energy harvester (TLPEH) were analyzed through finite-element analysis. The output voltage density is 4.251V/cm2 when 0.1N force is applied to the free end of ten-arm energy harvester. Comparisons of the resonant frequencies and output voltages were made. The first order resonant frequency could reach 15Hz by increasing the number of arms. Meanwhile, the output voltage is improved greatly when excited at first-order resonant frequencies. The trapezoidal-loop structure of TLPEH could enhance frequency response, which means scavenging energy more efficiently in vibration environment. The TLPEH mentioned here might be useful for the future structure design of piezoelectric energy harvester with low resonance frequency.

Approach for Effective Design and Cost Estimation of New built / Conversion FPSO (2014)

2014 ◽  
Author(s):  
Upendra Malla ◽  
Krishna M. Karri
Keyword(s):  
Cost Estimation ◽  
Structural Design ◽  
Effective Means ◽  
Step Method ◽  
Support Design ◽  
Field Development ◽  
Early Stages ◽  
The Cost ◽  
Offshore Field ◽  
Effective Design

Floating Production Storage and Offloading (FPSO) sizing and cost estimation has become a challenging task at the early stages of offshore field development. During the early stages of field development designer needs to size and estimate cost in order to decide feasibility of the project. This paper describes a step by step method used to size and estimate the cost of a new built (or) converted FPSO based on basic engineering, existing FPSO data and corresponding metocean criteria for a particular location. This step by step approach covers FPSO sizing, hull structural design, mooring sizing, topsides support design and steel renewal using offshore classification rules and regulations. FPSO cost is estimated based on the design particulars (i.e. hull weights, FPSO particulars, mooring sizes etc.) and current market unit rates. This approach is an effective means to size and estimate cost of an FPSO at early stages of field development which saves overall time and cost for a client.

Numerical Investigation of Ultimate Strength of Stiffened Plates With Various Cross-Section Forms

2018 ◽  
Author(s):  
Huilong Ren ◽  
Yifu Liu ◽  
Chenfeng Li ◽  
Xin Zhang ◽  
Zhaonian Wu
Keyword(s):  
Aluminum Alloy ◽  
Ultimate Strength ◽  
Cross Section ◽  
High Performance ◽  
Lightweight Design ◽  
Offshore Structures ◽  
Stiffened Plates ◽  
Stiffened Plate ◽  
Element Analysis ◽  
Hull Structure

There is an increasing interest in the lightweight design of ship and offshore structures, more specifically, choosing aluminum alloys or other lightweight high-performance materials to build structure components and ship equipments. Due to its better mechanical properties and easy assembly nature, extruded aluminum alloy stiffened plates are widely used in hull structures. When the load on the hull reaches a certain level during sailing, partial or overall instability of stiffened plate makes significant contribution in an event of collapse of the hull structure. It is very necessary to investigate the ultimate strength of aluminum alloy stiffened plate to ensure the ultimate bearing capacity of large aluminum alloy hull structure. Most of studies of the ultimate strength of stiffened plates deal with stiffened plates with T–shaped stiffeners. Stiffeners of other shapes have seldom been explored. In this research, the ultimate strength of six different cross–section aluminum alloy stiffened plates and one steel stiffened plate was studied based on the non–linear finite element analysis (FEA). Taking into account stiffness, weight and other issues, the new cross–section aluminum stiffener has finally been concluded for replacing the original steel stiffener in upper deck of a warship.

scholarly journals Strategy and numerical modelling of a vehicle seat with a lightweight sandwich design for large-scale production

2018 ◽  
Vol 1 (2) ◽  
Author(s):  
Song Ren ◽  
Kay Schäfer ◽  
Daisy Nestler ◽  
Dominik Krumm ◽  
Stephan Odenwald ◽  
...  
Keyword(s):  
Large Scale ◽  
Static Load ◽  
Lightweight Design ◽  
Scale Production ◽  
Front Seat ◽  
Element Analysis ◽  
Large Scale Production ◽  
Spacer Fabric ◽  
Glass Fibre Reinforced ◽  
Vehicle Seat

A lightweight vehicle front seat with a sandwich structure, which consists of skin layers made of glass fibre-reinforced thermoplastic prepregs and a core consisting of a warp knitted spacer fabric filled with polyurethane foam, was developed. The strength test simulations of the seat structure were performed using a Finite Element Analysis approach. The results validate the new sandwich design of the vehicle seat with its adequate strength under a static load. With the innovative lightweight design, the mass of the seat was reduced up to 57 % in comparison to the reference seat from conventional mass production. In addition, a manufacturing process was advised for a large-scale production of the lightweight design within one workstation.

IMPERFECTION SENSITIVITY AND RELIABILITY USING SIMPLE BAR-SPRING MODELS FOR STABILITY

2013 ◽  
Vol 13 (03) ◽  
pp. 1250075 ◽  
Author(s):  
VAHID ZEINODDINI MEIMAND ◽  
LORI GRAHAM-BRADY ◽  
BENJAMIN WILLIAM SCHAFER
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Ultimate Strength ◽  
Structural Reliability ◽  
Plastic Hinge ◽  
Continuous Systems ◽  
Plastic Collapse ◽  
Imperfection Sensitivity ◽  
Element Analysis ◽  
First Order

The objective of this paper is to demonstrate how simple bar-spring models can illustrate elementary and advanced structural behavior, including stability, imperfection sensitivity, and plastic collapse. In addition, the same bar-spring models also provide a ready means for assessing structural reliability. Bar-spring models for a column (both post-buckling stable and unstable), a frame, and a plate are all developed. For each model the influence of geometric imperfections are explicitly introduced and the ultimate strength considering plastic collapse of the supporting springs derived. The developed expressions are compared to material and geometric nonlinear finite element analysis models of analogous continuous systems, using yield surface based plastic hinge beam elements (in MASTAN) for the column and frame and shell elements (in ABAQUS) for the plate. The results show excellent qualitative agreement, and surprisingly good quantitative agreement. The developed bar-spring models are used in Monte Carlo simulations and in the development of first order Taylor Series approximations to provide the statistics of the ultimate strength as used in structural reliability calculations. Good agreement between conventional first order second moment assumptions and the Monte Carlo simulations of the bar-spring models is demonstrated. It is intended that the developed models provide a useful illustration of basic concepts central to structural stability and structural reliability.

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