Deformation Control Based on In-Situ Sensors for Mask Projection Based Stereolithography

2014 ◽  
Author(s):  
Kai Xu ◽  
Yong Chen
Keyword(s):  
Temperature Increase ◽  
Computer Aided Design ◽  
Test Case ◽  
Element Analysis ◽  
Ir Camera ◽  
Deformation Control ◽  
Fea Model ◽  
Building Process ◽  
Curl Distortion

Curl distortion is one of the main reasons for the part inaccuracy in the Mask Image Projection based Stereolithography (MIP-SL) process. During the building process, the photopolymerization of liquid resin leads to temperature increase. After cooling down, the cured layers will shrink while they are constrained by its supports or the previously built layers. Consequently, residue stresses exist in the built part and will lead to curl distortion after all the supports are removed. In this paper, we investigate the thermal effect in the building process by using an infrared (IR) camera as an in-situ temperature monitoring sensor. Test cases of cured layers with different shapes, sizes and layer thicknesses have been designed and tested. The experimental results show that the temperature increase of a cured layer is mainly related to its layer thickness, while its shapes and sizes have less effect. The temperature increase of a cured layer is also related to its building position in the Z axis. The calibrated temperature increases in the MIP-SL process can be incorporated in a Finite Element Analysis (FEA) model in order to simulate the curl distortion of a given computer-aided design model. Physical experiments of a simple test case have been built, measured, and compared with the FEA simulation result. A discussion of the curl distortion in the MIP-SL process including its prediction and compensation is given.

Photocuring Temperature Study for Curl Distortion Control in Projection-Based Stereolithography

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Kai Xu ◽  
Yong Chen
Keyword(s):  
Test Case ◽  
Test Cases ◽  
Ir Camera ◽  
Temperature Study ◽  
Building Process ◽  
Distortion Control ◽  
Curl Distortion ◽  
Different Shapes ◽  
Major Factors ◽  
Thermal Cooling

Polymerization shrinkage and thermal cooling effect have been identified as two major factors that lead to the curl distortion in the stereolithography apparatus (SLA) process. In this paper, the photocuring temperature during the building process of mask image projection-based stereolithography (MIP-SL) and how it affects parts' curl distortion are investigated using a high-resolution infrared (IR) camera. Test cases of photocuring layers with different shapes, sizes, and layer thicknesses have been designed and tested. The experimental results reveal that the temperature increase of a cured layer is mainly related to the layer thickness, while the layer shapes and sizes have little effect. The photocuring temperatures of built layers using different exposure strategies including varying exposure time, grayscale levels, and mask image patterns have been studied. The curl distortions of a test case based on various exposure strategies have been measured and analyzed. It is shown that, by decreasing the photocuring temperature of built layers, the exposure strategies using grayscale levels and mask image patterns can effectively reduce the curl distortion with the expense of increased building time. In addition to curl distortion control, the photocuring temperature study also provides a basis for the curl distortion simulation in the MIP-SL process.

scholarly journals A hybrid method technique for design and optimization of Formula race car exhaust muffler

2020 ◽  
Vol 11 (2) ◽  
pp. 174-180
Author(s):  
Barhm Mohamad ◽  
Jalics Karoly ◽  
Andrei Zelentsov ◽  
Salah Amroune
Keyword(s):  
Computer Aided Design ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Design Parameters ◽  
Piping System ◽  
Element Analysis ◽  
Software Analysis ◽  
Race Car ◽  
Fea Model ◽  
Car Exhaust

AbstractIn this work a multilevel Computational Fluid Dynamics (CFD) analysis has been applied for the design of a Formula race car exhaust muffler with improved characteristics of sound pressure level (SPL) and fluid dynamic response. The approaches developed and applied for the optimization process range from the 1D to fully 3D CFD simulation, exploring hybrid approaches based on the integration of a 1D model with 3D tools. Modern mufflers typically have a complex system of chambers and flow paths. There are a variety of sound damping and absorbing mechanisms working to quiet the sound flowing through a muffler and piping system. Two calculation methods were selected for this study. The muffler has a complex inner structure containing perforated pipe and fiber material. Computer-aided design (CAD) file of the muffler was established for developing Finite Element Analysis (FEA) model in AVL BOOST v2017 and another commercial advanced design software (SolidWorks 2017). FEA model was made to monitor the flow properties, pressure and velocity. After the model was verified, sensitivity studies of design parameters were performed to optimize the SPL of the muffler. The software analysis results are included in the paper. Recommendations are made for obtaining smoother SPL curves for various measurement methods.

Curing Temperature Study for Curl Distortion Control and Simulation in Projection Based Stereolithography

2014 ◽  
Author(s):  
Kai Xu ◽  
Yong Chen
Keyword(s):  
High Resolution ◽  
Curing Temperature ◽  
Test Case ◽  
Ir Camera ◽  
Temperature Study ◽  
Distortion Control ◽  
Curl Distortion ◽  
Major Factors ◽  
Thermal Cooling ◽  
Case Based

Polymerization shrinkage and thermal cooling effect have been identified as two major factors leading to the curl distortion in the Stereolithography (SLA) process. In this paper, the curing temperatures of built layers in the mask image projection based Stereolithography (MIP-SL) process are investigated using a high-resolution infrared (IR) camera. The curing temperatures of built layers using different exposure strategies including varying exposure time, grayscale levels and mask image patterns have been studied. The curl distortions of a test case based on various exposure strategies have been measured and analyzed. It is shown that, by decreasing the curing temperature of built layers, the exposure strategies using grayscale levels and mask image patterns can effectively reduce the curl distortion. In addition to curl distortion control, the curing temperature study also provides a basis for the curl distortion simulation in the MIP-SL process.

Shape Optimization of Fuel Cell Molded-on Gaskets for Robust Sealing

2006 ◽  
Author(s):  
Andreas Vlahinos ◽  
Kenneth Kelly ◽  
Kevin Mease ◽  
Jim Stathopoulos
Keyword(s):  
Computer Aided Design ◽  
Proton Exchange Membrane ◽  
Groove Depth ◽  
Proton Exchange ◽  
Hyperelastic Material ◽  
Element Analysis ◽  
Cross Sectional ◽  
Material Models ◽  
Fea Model ◽  
Sectional Shape

In typical Proton Exchange Membrane fuel cells, a compressed gasket provides a sealing barrier between cell and cooler bipolar plate interfaces. The gasket initially bears the entire bolt load, and its resisting reaction load depends on the cross-sectional shape of the gasket, bipolar plate’s groove depth, and the hyperelastic properties of the gasket material. A nonlinear, finite element analysis (FEA) model with various hyperelastic material models, large deformations, and contact was used to evaluate the load-gap curves. The deformed shapes and the distributions of stress, strain, and deflections are presented. Mooney-Rivlin and Arruda-Boyce hyperelastic material models were used, and a comparison of load-gap curves is shown. A process is presented that couples the computer-aided design geometry with the nonlinear FEA model that was used to determine the gasket’s cross-sectional shape, which achieves the desired reaction load for a given gap.

Tire Bead Overheating in Urban Buses and Trucks Using Drum Brake Systems

1998 ◽  
Vol 26 (1) ◽  
pp. 51-62
Author(s):  
A. L. A. Costa ◽  
M. Natalini ◽  
M. F. Inglese ◽  
O. A. M. Xavier
Keyword(s):  
Heat Transfer ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Energy ◽  
Structural Integrity ◽  
Experimental Temperature ◽  
Temperature Profiles ◽  
Element Analysis ◽  
Drum Brake ◽  
Fea Model

Abstract Because the structural integrity of brake systems and tires can be related to the temperature, this work proposes a transient heat transfer finite element analysis (FEA) model to study the overheating in drum brake systems used in trucks and urban buses. To understand the mechanics of overheating, some constructive variants have been modeled regarding the assemblage: brake, rims, and tires. The model simultaneously studies the thermal energy generated by brakes and tires and how the heat is transferred and dissipated by conduction, convection, and radiation. The simulated FEA data and the experimental temperature profiles measured with thermocouples have been compared giving good correlation.

DEVELOPMENT OF CALCITE REFERENCE MATERIALS FOR IN-SITU U-PB DATING AND TRACE-ELEMENT ANALYSIS

2016 ◽  
Author(s):  
Robert M. Holder ◽  
◽  
Bradley R. Hacker ◽  
Andrew R.C. Kylander-Clark
Keyword(s):  
Trace Element ◽  
Reference Materials ◽  
Trace Element Analysis ◽  
Element Analysis

Experimental Investigation of Laser Sintering of Conductive Adhesive for Functional Prototypes Produced by Embedding Stereolithography

2014 ◽  
Vol 1038 ◽  
pp. 75-81
Author(s):  
Bernd Niese ◽  
Philipp Amend ◽  
Uwe Urmoneit ◽  
Stephan Roth ◽  
Michael Schmidt
Keyword(s):  
Thermal Damage ◽  
Laser Sintering ◽  
Conductive Adhesive ◽  
Flexible Production ◽  
Sintering Process ◽  
Building Process ◽  
In Situ Generation ◽  
Functional Components

Embedding stereolithography (eSLA) is an additive, hybrid process, which provides a flexible production of 3D components and the ability to integrate electrical and optical conductive structures and functional components within parts. However, the embedding of conductive circuits in stereolithography (SLA) parts assumes usage of process technologies, which enables their direct integration of conductive circuits during the layer-wise building process. In this context, a promising method for in-situ generation of conductive circuits is dispensing of conductive adhesive on the current surface of the SLA part and its subsequent sintering. In this paper, the laser sintering (λ = 355 nm) of conductive adhesive mainly consisting of silver nanoparticles is investigated. The work intends to evaluate the curing behavior of the conductive adhesive, the beam-matter-interactions and the thermal damage of the SLA substrate. The investigations revealed a fast and flexible laser sintering process for the generation of conductive circuits with sufficient electrical conductivity and sufficient current capacity load. In this context, a characterization of the conductive structures is done by measuring their electrical resistance and their potential current capacity load.

scholarly journals Design and Characterization of Microscale Auxetic and Anisotropic Structures Fabricated by Multiphoton Lithography

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 446
Author(s):  
Ioannis Spanos ◽  
Zacharias Vangelatos ◽  
Costas Grigoropoulos ◽  
Maria Farsari
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mechanical Performance ◽  
Element Analysis ◽  
Mechanical Responses ◽  
Multiphoton Lithography ◽  
Anisotropic Structures ◽  
Scanning Electron

The need for control of the elastic properties of architected materials has been accentuated due to the advances in modelling and characterization. Among the plethora of unconventional mechanical responses, controlled anisotropy and auxeticity have been promulgated as a new avenue in bioengineering applications. This paper aims to delineate the mechanical performance of characteristic auxetic and anisotropic designs fabricated by multiphoton lithography. Through finite element analysis the distinct responses of representative topologies are conveyed. In addition, nanoindentation experiments observed in-situ through scanning electron microscopy enable the validation of the modeling and the observation of the anisotropic or auxetic phenomena. Our results herald how these categories of architected materials can be investigated at the microscale.

scholarly journals Discrete element analysis of the punching behaviour of a secured drapery system: from laboratory characterization to idealized in situ conditions

2021 ◽  
Author(s):  
Antonio Pol ◽  
Fabio Gabrieli ◽  
Lorenzo Brezzi
Keyword(s):  
Mechanical Response ◽  
Steel Wire ◽  
Discrete Element ◽  
Wire Mesh ◽  
Steel Plates ◽  
Loading Conditions ◽  
Element Analysis ◽  
In Situ Conditions ◽  
Wire Meshes

AbstractIn this work, the mechanical response of a steel wire mesh panel against a punching load is studied starting from laboratory test conditions and extending the results to field applications. Wire meshes anchored with bolts and steel plates are extensively used in rockfall protection and slope stabilization. Their performances are evaluated through laboratory tests, but the mechanical constraints, the geometry and the loading conditions may strongly differ from the in situ conditions leading to incorrect estimations of the strength of the mesh. In this work, the discrete element method is used to simulate a wire mesh. After validation of the numerical mesh model against experimental data, the punching behaviour of an anchored mesh panel is investigated in order to obtain a more realistic characterization of the mesh mechanical response in field conditions. The dimension of the punching element, its position, the anchor plate size and the anchor spacing are varied, providing analytical relationships able to predict the panel response in different loading conditions. Furthermore, the mesh panel aspect ratio is analysed showing the existence of an optimal value. The results of this study can provide useful information to practitioners for designing secured drapery systems, as well as for the assessment of their safety conditions.

Sign in / Sign up

Export Citation Format

Share Document