Design of Precise Lightweight Mirror

2013 ◽  
Vol 284-287 ◽  
pp. 2717-2722
Author(s):  
Tomáš Vít ◽  
Radek Melich ◽  
Jan Václavík ◽  
Vít Lédl
Keyword(s):  
Mechanical Design ◽  
Optical Glass ◽  
Point Of View ◽  
Mechanical And Thermal Properties ◽  
Shape Accuracy ◽  
Space Applications ◽  
Lightweight Structures ◽  
Optical Surfaces ◽  
Lightweight Structure ◽  
Strength And Stiffness

The presented paper shows results from the mechanical design of lightweight mirrors for space applications, where demand for maximum weight loss goes together with demands for sufficient strength, shape accuracy, and surface quality of optical surfaces. The paper illustrates the material properties of different materials, which are often used for manufacturing precise optics. It compares three materials – e.g. optical glass such as NFS-15, optical ceramic such as Zerodur, and Silicon-infiltrated sintered Silicon Carbide – from the point of view of suitability for machining and their mechanical and thermal properties. It also shows the possibility of mass reduction by using different geometries of lightweight structure. Paper shows the results of numerical simulations of specified load-cases and comparison of different lightweight structures and different materials with respect to their strength and stiffness.

scholarly journals Investigation of Energy-Absorbing Properties of a Bio-Inspired Structure

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 881
Author(s):  
Adrian Dubicki ◽  
Izabela Zglobicka ◽  
Krzysztof J. Kurzydłowski
Keyword(s):  
Absorption Capacity ◽  
Compression Tests ◽  
Element Analysis ◽  
Lightweight Structures ◽  
New Energy ◽  
Absorbing Material ◽  
Lightweight Structure ◽  
3D Printed ◽  
Deformation Force ◽  
Energy Absorbing

Numerous engineering applications require lightweight structures with excellent absorption capacity. The problem of obtaining such structures may be solved by nature and especially biological structures with such properties. The paper concerns an attempt to develop a new energy-absorbing material using a biomimetic approach. The lightweight structure investigated here is mimicking geometry of diatom shells, which are known to be optimized by nature in terms of the resistance to mechanical loading. The structures mimicking frustule of diatoms, retaining the similarity with the natural shell, were 3D printed and subjected to compression tests. As required, the bio-inspired structure deformed continuously with the increase in deformation force. Finite element analysis (FEA) was carried out to gain insight into the mechanism of damage of the samples mimicking diatoms shells. The experimental results showed a good agreement with the numerical results. The results are discussed in the context of further investigations which need to be conducted as well as possible applications in the energy absorbing structures.

scholarly journals An Experimental Characterization of TORVEastro, Cable-Driven Astronaut Robot

Robotics ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 21
Author(s):  
Francesco Samani ◽  
Marco Ceccarelli
Keyword(s):  
Mechanical Design ◽  
Vision System ◽  
Service Robot ◽  
Test Results ◽  
Operation Performance ◽  
Space Applications ◽  
Outdoor Space ◽  
Motion Characteristics ◽  
Three Degree Of Freedom

TORVEastro robot design is presented with a built prototype in LARM2 (Laboratory of Robot Mechatronics) for testing and characterizing its functionality for service in space stations. Several robot astronauts are designed with bulky human-like structures that cannot be convenient for outdoor space service in monitoring and maintenance of the external structures of orbital stations. The design features of TORVEastro robot are discussed with its peculiar mechanical design with 3 arm-legs as agile service robot astronaut. A lab prototype is used to test the operation performance and the feasibility of its peculiar design. The robot weighs 1 kg, and consists of a central torso, three identical three-degree of freedom (DoF) arm–legs and one vision system. Test results are reported to discuss the operation efficiency in terms of motion characteristics and power consumption during lab experiments that nevertheless show the feasibility of the robot for outdoor space applications.

DIGITAL FABRICATION AS A LEARNING MEDIA FOR LIGHTWEIGHT STRUCTURE WITH CASE STUDY OF SHELL STRUCTURE

MODUL ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 126-133
Author(s):  
Stephanus Evert Indrawan ◽  
LMF Purwanto
Keyword(s):  
Shell Structure ◽  
Laser Cutting ◽  
Digital Fabrication ◽  
Scalar Model ◽  
Structure System ◽  
Lightweight Structures ◽  
Digital Devices ◽  
Lightweight Structure ◽  
Realization Process

The lightweight structure system is an effort to optimize the structure to distribute the load efficiently. Unfortunately, students often have difficulty imagining the learning outcomes application in the real world when studying light structural systems. However, the use of the scalar model can still explain several essential aspects of a lightweight structural system, one of which is the effect of connection and formation of material components on the structural capability. Therefore, this paper aims to bridge the learning process by utilizing digital devices from the concept stage of structural modeling with the help of software (Rhinoceros, Grasshopper, and Kangaroo) to the realization process using laser cutting. The method used is a semi-experimental method that applies Hooke's law principle, which produces a shell structure system with a digital fabrication approach that utilizes a lightweight material, namely, corrugated paper board, as the primary material. This paper concludes that digital technology and digital fabrication processes can help students understand the concept of lightweight structures because they can use computer simulations, cut them using laser cutting, and assemble them in the field in a series of simultaneous processes. 

Design of the Lightweight Structure and its Mechanical Properties

2013 ◽  
Vol 461 ◽  
pp. 57-62
Author(s):  
Xiao Ting Jiang ◽  
Ce Guo ◽  
Xiu Yan Cao ◽  
Zhen Yu Lu
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Fiber Material ◽  
Element Analysis ◽  
Static Compression ◽  
Lightweight Structures ◽  
Carbon Fiber Material ◽  
The Finite Element Analysis ◽  
Lightweight Structure

Based on the microstructure of the cross-section of the beetle's elytra, a kind of bio-inspiredlightweight structure was designed and made by the carbon fiber material. The compressive andshear mechanical properties of the lightweight structures were studied with finite element method.In addition, quasi-static compression experiments of the structure samples were carried out. Theexperimental results and the finite element analysis results were compared and analyzed, whichproved the effectiveness of the finite element analysis.

Static and Dynamic Analysis of Motor Cycle Wheel Designs

2015 ◽  
Vol 813-814 ◽  
pp. 915-920 ◽  
Author(s):  
A. Eswara Kumar ◽  
M. Naga Raju ◽  
Navuri Karteek ◽  
Daggupati Prakash
Keyword(s):  
Vital Role ◽  
Point Of View ◽  
Al Alloy ◽  
Analysis Tool ◽  
Structural Stiffness ◽  
Element Analysis ◽  
Static And Dynamic Analysis ◽  
Wheel Rim ◽  
Strength And Stiffness ◽  
Von Mises

The wheel of a vehicle plays a vital role to bear the load applies on it. Generally spokes acts as the supports between the wheel rim and hub. These spokes must have sufficient strength and stiffness to avoid the failure of the wheel. In present days these wheels are made up of aluminum alloy, magnesium alloy and steel. To reduce the weight of the wheel many wheel designs are implemented and applied for different vehicles. In this paper three different wheel designs are chosen, those are inclined spokes, curved spokes and Y shaped spokes made up of Al alloy, Mg alloy and Steel. Static structural analysis subjected to pressure on the wheel rim and free vibrational analyses are performed by using finite element analysis tool Ansys 12. The objective of the present work is to observe the best design which contains higher structural stiffness, specific structural stiffness with lower von mises stresses under static load conditions. It is observed that curve shaped spoke designs are better in for manufacturing of wheel in both static and dynamic point of view.

Identification and Analysis of Residual Stresses in the Axisymmetric Workpiece Existing before and after Machining

2016 ◽  
Vol 686 ◽  
pp. 33-38 ◽  
Author(s):  
Tadeusz Otko ◽  
Wojciech Zębala
Keyword(s):  
Point Of View ◽  
Internal Stresses ◽  
Entire Volume ◽  
Shape Accuracy ◽  
Workpiece Surface ◽  
Plastic Processing ◽  
Machining Allowance ◽  
Before And After ◽  
The Impact

Semi-manufactured parts dedicated for precise machining often have internal stresses which have remained after previous cutting and plastic processing. These stresses reside in a fixed state of balance over the entire volume of the workpiece. Removal of the machining allowance is associated with a change in the state of balance and deformation of the workpiece, which affect its dimensional and shape accuracy. The study, involving non-stress removal of precisely defined volume of the machining allowance and determination of the impact of this treatment on the deformation of the workpiece surface is presented. It is important from the point of view of dimensional tolerance of the axially symmetrical workpiece, finally processed by turning.

scholarly journals IMPROVING RESILIENCE IN ARCHITECTURAL HERITAGE? THE RECONSTRUCTION OF THE VAULTING SYSTEMS AFTER THE 1805 EARTHQUAKE IN MOLISE (ITALY)

2020 ◽  
Vol XLIV-M-1-2020 ◽  
pp. 921-928
Author(s):  
L. Romano
Keyword(s):  
Southern Italy ◽  
Point Of View ◽  
Architectural Heritage ◽  
Large Area ◽  
Lightweight Structures ◽  
Clay Bricks ◽  
Construction Techniques ◽  
Poor Region ◽  
Formal Point

Abstract. The 1805 earthquake damaged a large area of the Southern Italy, destroying most of the architectural heritage in the “Contado of Molise”, a poor region characterized by numerous medieval towns. In the aftermath of the catastrophe, the reconstruction and in fewer cases the restoration of important buildings, mainly the ecclesiastical ones, took place without a well-defined rebuilding plan. If, from a formal point of view, interesting design levels were not reached, the same cannot be stated for the construction solutions adopted, especially regarding vaulted systems. Actually, they were conceived either with wood, concrete with aggregates or full/hollow clay bricks. This variety of constructive raw elements is a direct manifestation of the richness of the vernacular constructive tradition. Moreover, the intrinsic lightness of such materials suggests as well the need at the time of new lightweight structures capable of standing on pre-existing weakened masonries. This approach was probably taken in order to reduce vulnerability and improve structural resilience to earthquakes. In light of these considerations, the paper focuses on the different construction techniques used to rebuild the vaulting systems after the 1805 earthquake in Molise, discussing their potentialities and weaknesses as well as their capacity to improve resilience in the architectural heritage.

scholarly journals Mechanical and tribological behaviour of PA6 and short aramid fiber composites

2021 ◽  
Vol 13 (4) ◽  
pp. 47-58
Author(s):  
George Catalin CRISTEA ◽  
Adriana STEFAN ◽  
George PELIN ◽  
Cristina-Elisabeta PELIN ◽  
Maria SONMEZ ◽  
...  
Keyword(s):  
Mechanical Test ◽  
Polyamide 6 ◽  
Mechanical Tests ◽  
Point Of View ◽  
Mechanical And Thermal Properties ◽  
Tribological Behaviour ◽  
Tribological Test ◽  
Three Point Bending ◽  
Mechanical And Tribological Characteristics ◽  
Structural Point

This paper presents the results of mechanical and tribological characteristics for two composites: PA6 as matrix and 5% aramid whiskers as additive material and PA6 + 10% aramid whiskers, comparing them to those made of PA6 (polyamide 6). To improve the mechanical and thermal properties of polyamide (PA6), the composites were prepared via the Brabender lab mixer and mould forming under given pressure and temperature conditions. Test specimens made of pure PA6 and PA6 mixed with 5 wt.% and 10 wt.% aramid whiskers were subjected to mechanical tests (three-point bending and impact), thermo–mechanical test (HDT - heat deflection temperature), tribological test (block-on-ring) and analyzed from morpho-structural point of view. Compared to the PA6 samples, the mass concentrations of aramid whiskers improved the HDT deflection temperature values. In the case of samples with 5% aramid whiskers, the absorbed energy increased by 13% and for those with 10% aramid whiskers they increased by 30%. Aramid whiskers-doped materials performed much better on severe tribological testing as compared to PA6 samples. Increasing the deflection temperature, also improved their resistance from a tribological point of view.

scholarly journals Optimizing lightweight structures with particle damping using frequency based substructuring

2020 ◽  
Vol 6 ◽  
Author(s):  
J. Oltmann ◽  
T. Hartwich ◽  
D. Krause
Keyword(s):  
Mechanical Design ◽  
Experimental Testing ◽  
Mass Gain ◽  
Large Mass ◽  
Structural Dynamic ◽  
Lightweight Structures ◽  
Particle Damping ◽  
Subsequent Discussion ◽  
Development Processes ◽  
Operating Points

In many cases, the use of damping technologies is the only option to reduce undesired vibrations. Despite various damping techniques available on the market, the design of a precise damping behaviour still needs a lot of experimental testing and engineering experience. This is also the case for particle damping. However, for lightweight structures, technologies such as particle damping provide an opportunity to improve the structural dynamic behaviour without a large mass gain. With respect to this conflict, a hybrid numerical and experimental design approach is presented based on frequency based substructuring (FBS). With this technique, the use of experimental data for design optimization is possible and detailed modelling of the nonlinear particle damping system can be avoided. Moreover, based on the FBS, an approach to optimize damping and weight is proposed. All results are compared to experiments, and a subsequent discussion shows that the predictions for particle damping with FBS are accurate for defined operating points from which realistic designs can be derived. Generally, it is shown that methodical design approaches may strongly improve not only product development processes but also structural mechanical design.

The Effect of Parent Metal Properties on the Performance of Lattice Block MaterialTM

1998 ◽  
Vol 521 ◽  
Author(s):  
M. L. Renauld ◽  
A. F. Giamei ◽  
M. S. Thompson ◽  
J. Priluck
Keyword(s):  
Copper Alloys ◽  
Internal Node ◽  
Compression Tests ◽  
Parent Metal ◽  
Element Analysis ◽  
Lightweight Structure ◽  
Strength And Stiffness ◽  
Metal Properties ◽  
Experimental Findings ◽  
The Relationship

ABSTRACTLattice Block MaterialTM, or LBMTM is a unique lightweight structure consisting of repeated cells with an internal node connected to, in the most common configuration, 14 ligaments. In its metallic version, this product is available in a variety of castable metals including aluminum alloys, copper alloys, nickel alloys and steels. The relationship between LBMTM structural performance (strength and stiffness) and parent metal properties is investigated using compression tests in three primary orientations and 3-pt. bend tests. Analytical assessment of the LBMTM via finite element analysis shows reasonable agreement with experimental findings and provides predictions for LBMTM capabilities with different materials, unit cell sizes and ligament geometries.

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