Coupled Computation of Fluid and Material Response for Non-Charring Ablative Materials in Hypersonic Flow

Hypersonic vehicles are subjected to high heat loads throughout their flight trajectories, and as a result, some form of thermal protection system (TPS) is required to ensure the vehicle’s survival. Accurate prediction of the behavior of these materials in a hypersonic environment is crucial to the efficient design of a hypersonic flight vehicle. It can be very costly and difficult, however, to experimentally replicate the flow conditions found in many hypersonic regimes, and for this reason it is desirable to be able to simulate the behavior of TPS materials under these flight conditions. This study aims to improve the modeling of the coupled fluid-material response problem for TPS materials in realistic hypersonic flows by coupling a hypersonic CFD code with an axisymmetric material response code

The design and implementation of material and information flow for manufacturing systems

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2000.Includes bibliographical references (p. 143-145).Production systems are characterized by complex interactions between elements, both human and mechanical, with the goal to accomplish certain high-level manufacturing objectives. In order to ensure that the decisions made and the actions taken during the design and implementation of production systems are aligned with all of the objectives, a structured approach must be followed. In developing this structured approach, the axiomatic design methodology is applied, which provides the means for creating a hierarchy of system design objectives (what to do) and solutions (how to do it). From this conceptual design process, a Production System Design and Implementation (PSDI) Path is presented here. The PSDI Path guides the design through a series of steps in creating a successful physical manufacturing system environment in terms of the original high-level objectives. Defining the material and information flow in the system is a critical part of the PSDI path. Based on the steps in the PSDI Path and the design hierarchy, a procedure for constructing the material and information flow in the production system is developed. To aid in the design of material and information flow in the manufacturing system, a manufacturing system modeling environment is developed as the tool for visualizing and communicating the flow in the manufacturing system design. KEYWORDS: Lean Manufacturing, Value Stream Management, Manufacturing System Design, Production System Design, Cellular Manufacturing, Axiomatic Design.by Brandon J. Carrus.S.M

Design of a high-temperature experiment for evaluating advanced structural materials

This report describes the design of an experiment for evaluating monolithic and composite material specimens in a high-temperature environment and subject to big thermal gradients. The material specimens will be exposed to aerothermal loads that correspond to thermally similar engine operating conditions. Materials evaluated in this study were monolithic nickel alloys and silicon carbide. In addition, composites such as tungsten/copper were evaluated. A facility to provide the test environment has been assembled in the Engine Research Building at the Lewis Research Center. The test section of the facility will permit both regular and Schlieren photography, thermal imaging, and laser Doppler anemometry. The test environment will be products of hydrogen-air combustion at temperatures from about 1200 F to as high as 4000 F. The test chamber pressure will vary up to 60 psia, and the free-stream flow velocity can reach Mach 0.9. The data collected will be used to validate thermal and stress analysis models of the specimen. This process of modeling, testing, and validation is expected to yield enhancements to existing analysis tools and techniques

The role of primitive part modelling within an integrative simulation environment

The component-based modeling approach to the simulation of HVAC systems has been in used for many years. The approach not only supports plant simulation but also allows the integration of the building and plant domains. Frequently, however, the plant models do not match exactly the types being used in a given project and where they do, may not be able to provide the required information. To address such limitations research has been undertaken into alternative approaches. The aim of such research is to provide a modeling approach that is widely applicable and offers efficient code management and data sharing. Primitive Part (PP) modeling is one such effort, which employs generic, process-based elements to attain modeling flexibility. Recent efforts have been on the development of data structure and graphics that facilitates PP auto-connection via computer interface. This paper describes the approach using an example application and its suggested role within an integrative simulation environment

Manufacturing Process Modeling and Simulation

This paper presents a methodology to be employed in the whole process design phase including first and second processing. This methodology consists of a set of steps which are characterised by an independent model. This paper’s objective is to analyse the coherence between the different models and the coherence between the model and the objectives of each step. The final stage is to develop the production plans. The casting process was the first one to be analyzed. Casting models were created using CAD software (Catia V5R17) and imported into the casting simulation environment (Magmasoft). Filling and solidifying processes have been simulated using different casting models in order to optimize the final configuration. The machining process was modeled using the machining features concept and it was simulated using Catia’s Advanced Machining environment. Two machining strategies have been analyzed according to positioning strategies. Process engineering software was used to create the process plans and to analyze the resource allocation

Modeling of Traceability Information System for Material Flow Control Data.

This paper focuses on data modeling for traceability of material/work flow in information layer of manufacturing control system. The model is able to trace all associated data throughout the product manufacturing from order to final product. Dynamic data processing of Quality and Purchase activities are considered in data modeling as well as Order and Operation base on lots particulars. The modeling consisted of four steps and integrated as one final model. Entity-Relationships Modeling as data modeling methodology is proposed. The model is reengineered with Toad Data Modeler software in physical modeling step. The developed model promises to handle fundamental issues of a traceability system effectively. It supports for customization and real-time control of material in flow in all levels of manufacturing processes. Through enhanced visibility and dynamic store/retrieval of data, all traceability usages and applications is responded. Designed solution is initially applicable as reference data model in identical lot-base traceability system

NASA Lewis Research Center low-gravity fluid management technology program

A history of the Lewis Research Center in space fluid management technology program is presented. Current programs which include numerical modeling of fluid systems, heat exchanger/radiator concept studies, and the design of the Cryogenic Fluid Management Facility are discussed. Recent analytical and experimental activities performed to support the Shuttle/Centaur development activity are highlighted

Ship product modelling

This paper is a fundamental review of ship product modeling techniques with a focus on determining the state of the art, to identify any shortcomings and propose future directions. The review addresses ship product data representations, product modeling techniques and integration issues, and life phase issues. The most significant development has been the construction of the ship Standard for the Exchange of Product Data (STEP) application protocols. However, difficulty has been observed with respect to the general uptake of the standards, in particular with the application to legacy systems, often resulting in embellishments to the standards and limiting the ability to further exchange the product data. The EXPRESS modeling language is increasingly being superseded by the extensible mark-up language (XML) as a method to map the STEP data, due to its wider support throughout the information technology industry and its more obvious structure and hierarchy. The associated XML files are, however, larger than those produced using the EXPRESS language and make further demands on the already considerable storage required for the ship product model. Seamless integration between legacy applications appears to be difficult to achieve using the current technologies, which often rely on manual interaction for the translation of files. The paper concludes with a discussion of future directions that aim to either solve or alleviate these issues

The influencing mechanism of manufacturing scene change on process domain knowledge reuse

It is necessary for a enterprise to reuse outside process domain knowledge to develop intelligent manufacturing technology. The key factors influencing knowledge reuse in digital manufacturing scene are manufacturing activities and PPR (Products, Processes and Resources) related to knowledge modeling, enterprise and integrated systems related to knowledge utilizing. How these factors influence knowledge modeling and utilizing is analyzed. Process domain knowledge reuse across the enterprises consists of knowledge reconfiguration and integrated application with CAx systems. The module-based knowledge model and loosely-coupled integration application of process domain knowledge are proposed. The aircraft sheet metal process domain knowledge reuse is taken as an example, and it shows that the knowledge reuse process can be made flexible and rapid