scholarly journals Efficient Distortion Prediction of Additively Manufactured Parts Using Bayesian Model Transfer Between Material Systems

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Jack Francis ◽  
Arman Sabbaghi ◽  
M. Ravi Shankar ◽  
Morteza Ghasri-Khouzani ◽  
Linkan Bian
Keyword(s):  
Bayesian Model ◽  
Computation Time ◽  
Critical Issue ◽  
Material System ◽  
Element Analysis ◽  
Distortion Model ◽  
Material Systems ◽  
New Material ◽  
Model Transfer

Abstract Distortion in laser-based additive manufacturing (LBAM) is a critical issue that adversely affects the geometric integrity of additively manufactured parts and generally exhibits a complicated dependence on the underlying material. The differences in properties between distinct materials prevent the immediate application of a distortion model learned for one material to another, which introduces the challenge in LBAM of learning a distortion model for a new material system given past experiments. Current methods for investigating the distortion of different material systems typically involve finite element analysis or a large number of experiments in an empirical study. However, these methods do not learn from previous experiments and can incur significant costs in terms of computation, time, or resources. We propose a Bayesian model transfer methodology that is both physics-based and data-driven to leverage past experiments on previously studied material systems for more efficient distortion modeling of new systems. This method transfers distortion models across distinct materials based on the statistical effect equivalence framework by formulating the differences between two materials as a lurking variable. Our method reduces the experimentation and effort needed for specifying distortion models for new material systems. We validate our methodology in a case study of distortion model transfer from Ti–6Al–4V disks to 316L stainless steel disks. This case study is the first instance of model transfer between material systems and illustrates the ability of the Bayesian model transfer methodology to address the issue of comprehensive distortion modeling across varying material systems in LBAM.

scholarly journals Experimental and Numerical Studies on Ballistic Laminates on the Polyethylene and Polypropylene Matrix

2017 ◽  
Vol 35 (02) ◽  
pp. 187-197 ◽  
Author(s):  
P. Mayer ◽  
D. Pyka ◽  
K. Jamroziak ◽  
J. Pach ◽  
M. Bocian
Keyword(s):  
Hybrid Composite ◽  
Material System ◽  
Aramid Fibers ◽  
Advantages And Disadvantages ◽  
Numerical Studies ◽  
Thermoplastic Matrix ◽  
Material Systems ◽  
New Material ◽  
Innovative Material ◽  
Polypropylene Matrix

ABSTRACTThe paper analyzes the issues relating to the applicability of innovative material systems for flexible composite armors. The authors made several samplings of aramid fibers (Kevlar 49) by replacing the epoxy resin base, which is often described in the literature, with the thermoplastic matrix - polyethylene (HDPE) and polypropylene (PP). The samples were fired with .38 Special Full Metal Jacketed (FMJ) ammunition produced by the S&B Company, and then the process of firing was modeled in the ABAQUS program. The advantages and disadvantages of the new material system including the possibility of its use in the construction of hybrid composite armors have been presented on the basis of the results of numerical analyses and ballistic tests.

A Slim Sector Model for the Analysis of Fatigue Life of Fine Pitch Flip Chip Packages

2005 ◽  
Author(s):  
Bing Zhao ◽  
Andrew A. O. Tay
Keyword(s):  
Fatigue Life ◽  
Flip Chip ◽  
Computation Time ◽  
Critical Issue ◽  
Temperature Cycling ◽  
Element Analysis ◽  
Sector Model ◽  
Fine Pitch ◽  
Time Required ◽  
Diagonal Plane

In the near future, it is likely that the interconnection pitch of flip chips will fall below 100 microns. For a flip chip of 20mm × 20mm at this pitch, there will be 40,000 interconnections on the chip. Even after taking advantage of symmetry whereby only a one-eighth model need be analyzed, there will be 5,000 interconnections. If solder were used to form the interconnection, plasticity and creep effects would need to be taken into account. Despite the great advances in computer technology, the computer memory and computation time required for a full 3D finite element analysis (FEA) of such a fine-pitch IC package is prohibitive. This paper presents a slim sector model which could be used to overcome this problem. Essentially, a slim sector of the package adjacent to the diagonal is analyzed rather than a 1/8 model. The appropriate boundary condition to be applied to the slim sector model is a critical issue. With the large number of interconnections, it is reasonable to expect that the displacement of points close to the diagonal plane of the package will tend to be directed radially outwards from the neutral point at the centre of the package. The validity of this assumption was investigated by performing a full 3D FEA of the 1/8 model of two flip chip packages of dimensions 4mm square and 6mm square. A few slim sector models have been developed and their accuracy and computational efficiency studied. The fatigue life of the critical solder joint was determined by performing a temperature cycling simulation between −40C and 150C. The elastoplastic and creep properties of solder were taken into account. As the 1/8 model is the most accurate model, its results were taken as reference. It was found that the accuracy of the best slim sector model ranged between 12% and 27%. A comparison was also made between the slim sector model and the popular strip model. It was found that the slim sector model was much more accurate than the strip model which gives error of 61–248%.

Application of CAD/CAE, Reverse Engineering and Rapid Prototyping in New Product Development Industry

2013 ◽  
Author(s):  
Muni Prabaharan
Keyword(s):  
Rapid Prototyping ◽  
Product Design ◽  
New Product Development ◽  
Mechanical Characteristics ◽  
Failure Modes ◽  
New Product ◽  
Element Analysis ◽  
New Material ◽  
Fea Simulation

This paper is written based on some industrial practices. It presents some aspects about rapid prototyping which stays at the base of manufacturing design using CAD/CAE programs and its integration in industrial field. A big economical advantage is that products made by rapid prototyping express a low risk failure and the manufacturing process takes less time and lower costs than the conventional techniques. A new product design was produced by rapid prototyping techniques starting from a broken one. First, the mechanical characteristics of broken product were investigated by Finite Element Analysis (FEA). It provides a way of simulating the product design under working condition and an opportunity to understand failure modes. Therefore, problems in tooling would be minimized. After FEA simulation, a new material was chosen in order to increase the mechanical characteristics. The new product material improves all the mechanical characteristics. At the end of this paper, the case study is presented. Before that, new framework is proposed.

Cross-sectional TEM specimen preparation from magneto-optical disk by ultramicrotomy

1993 ◽  
Vol 51 ◽  
pp. 236-237
Author(s):  
F. Shaapur ◽  
M.J. Kim ◽  
Seh Kwang Lee ◽  
Soon Gwang Kim
Keyword(s):  
System Development ◽  
Thin Foil ◽  
Specimen Preparation ◽  
Material System ◽  
Cross Sectional ◽  
Protective Layers ◽  
New Material ◽  
Diamond Saw ◽  
Original Production ◽  
Thick Medium

TEM characterization and microanalysis of the recording media is crucial and complementary to new material system development as well as quality control applications. Due to the type of material generally used for supporting the medium, i.e., a polymer, conventional macro- and microthinning procedures for thin foil preparation are not applicable. Ultramicrotorny (UM) is a viable option and has been employed in previous similar studies. In this work UM has been used for preparation of XTEM samples from a magneto-optical (MO) recording medium in its original production format.The as-received material system consisted of a 4-layer, 2100 Å thick medium including a 300 Å TbFeCo layer enveloped by silicon nitride protective layers supported on a 1.2 mm thick × 135 mm (5.25 in.) diameter polycarbonate disk. Recording tracks had an approximate pitch of 1.6 μm separated by 800 Å deep peripheral grooves. Using a Buehler Isomet low-speed diamond saw, 1 mm wide and 20 mm long strips were cut out of the disk along the recording tracks.

scholarly journals Reservoir Sediment Management Using Artificial Neural Networks: A Case Study of the Lower Section of the Alpine Saalach River

Water ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 818
Author(s):  
Markus Reisenbüchler ◽  
Minh Duc Bui ◽  
Peter Rutschmann
Keyword(s):  
Real World ◽  
Close Correlation ◽  
Critical Issue ◽  
Management Tool ◽  
Lower Section ◽  
Reservoir Sediment ◽  
Efficiency And Effectiveness ◽  
Artificial Neural ◽  
Artificial Neural Network Ann

Reservoir sedimentation is a critical issue worldwide, resulting in reduced storage volumes and, thus, reservoir efficiency. Moreover, sedimentation can also increase the flood risk at related facilities. In some cases, drawdown flushing of the reservoir is an appropriate management tool. However, there are various options as to how and when to perform such flushing, which should be optimized in order to maximize its efficiency and effectiveness. This paper proposes an innovative concept, based on an artificial neural network (ANN), to predict the volume of sediment flushed from the reservoir given distinct input parameters. The results obtained from a real-world study area indicate that there is a close correlation between the inputs—including peak discharge and duration of flushing—and the output (i.e., the volume of sediment). The developed ANN can readily be applied at the real-world study site, as a decision-support system for hydropower operators.

scholarly journals Behavior of Offshore Pile in Calcareous Sand—Case Study

2021 ◽  
Vol 9 (8) ◽  
pp. 839
Author(s):  
Tarek N. Salem ◽  
Nadia M. Elkhawas ◽  
Ahmed M. Elnady
Keyword(s):  
Load Capacity ◽  
High Stress ◽  
Embedment Depth ◽  
Shear Stresses ◽  
Northern Coast ◽  
Compression Tests ◽  
Calcareous Sand ◽  
Element Analysis ◽  
Mixing Ratios

The erosion of limestone and calcarenite ridges that existed parallel to the Mediterranean shoreline forms the calcareous sand (CS) formation at the surface layer of Egypt's northern coast. The CS is often combined with broken shells which are considered geotechnically problematic due to their possible crushability and relatively high compressibility. In this research, CS samples collected from a site along the northern coast of Egypt are studied to better understand its behavior under normal and shear stresses. Reconstituted CS specimens with different ratios of broken shells (BS) are also investigated to study the effect of BS ratios on the soil mixture strength behavior. The strength is evaluated using laboratory direct-shear and one-dimensional compression tests (oedometer test). The CS specimens are not exposed to significant crushability even under relatively high-stress levels. In addition, a 3D finite element analysis (FEA) is presented in this paper to study the degradation offshore pile capacity in CS having different percentages of BS. The stress–strain results using oedometer tests are compared with a numerical model, and it gave identical matching for most cases. The effects of pile diameter and embedment depth parameters are then studied for the case study on the northern coast. Three different mixing ratios of CS and BS have been used, CS + 10% BS, CS + 30% BS, and CS + 50% BS, which resulted in a decrease of the ultimate vertical compression pile load capacity by 8.8%, 15%, and 16%, respectively.

Attribute Based Selection of Thermoplastic Resin for Vacuum Infusion Process

2011 ◽  
Vol 1 (3) ◽  
pp. 31-52 ◽  
Author(s):  
R. T. Durai Prabhakaran ◽  
Aage Lystrup ◽  
Tom Løgstrup Andersen
Keyword(s):  
Material System ◽  
Mathematical Tool ◽  
Thermoplastic Resin ◽  
Thermoplastic Polymers ◽  
Vacuum Infusion ◽  
Thermosetting Polymers ◽  
Current Scenario ◽  
New Material ◽  
Selection Of ◽  
Vacuum Infusion Process

The composite industry looks toward a new material system (resins) based on thermoplastic polymers for the vacuum infusion process, similar to the infusion process using thermosetting polymers. A large number of thermoplastics are available in the market with a variety of properties suitable for different engineering applications, and few of those are available in a not yet polymerised form suitable for resin infusion. The proper selection of a new resin system among these thermoplastic polymers is a concern for manufactures in the current scenario and a special mathematical tool would be beneficial. In this paper, the authors introduce a new decision making tool for resin selection based on significant attributes. This article provides a broad overview of suitable thermoplastic material systems for vacuum infusion process available in today’s market. An illustrative example—resin selection for vacuum infused of a wind turbine blade—is shown to demonstrate the intricacies involved in the proposed methodology for resin selection.

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