Devi K. Kalla

MULTIPLE REGRESSION AND COMMITTEE NEURAL NETWORK FORCE PREDICTION MODELS IN MILLING FRP

This work utilizes the mechanistic modeling approach for predicting cutting forces and simulating the milling process of fiber-reinforced polymers (FRP) with a straight cutting edge. Specific energy functions were developed by multiple regression analysis (MR) and committee neural network approximation (CN) of milling force data and a cutting model was developed based on these energies and the cutting geometry. It is shown that both MR and CN models are capable of predicting the cutting forces in milling of unidirectional and multidirectional composites. Model predictions were compared with experimental data and were found to be in good agreement over the entire range of fiber orientations from 0 to 180°. Furthermore, CN model predictions were found to greatly outperform MR model predictions.

Unit Process Life Cycle Inventory for Product Manufacturing Operations

Rapid access to or generation of life cycle information is a potentially valuable tool for the design of products to meet the needs of sustainability improvement. A new approach is developed to use the manufacturing unit process, commonly outlined in manufacturing process taxonomy systems, as the basis for life cycle inventory. This will initially involve 50–70 unit processes from the taxonomy and will generate energy and mass profiles for each unit process life cycle (uplci). These uplci can be adjusted for each case to include the major variables affecting such operations as related to any specific product. The sum of the performance of a sequence of uplci thus provides the life cycle of the specific product from a defined set of plant process inputs.Copyright

Current Research Trends in Abrasive Waterjet Machining of Fiber Reinforced Composites

The use of fiber reinforced polymer (FRP) composites in the aircraft and automotive industries exponentially. Reinforced fibers which are abrasive in nature make it hard to machine by the traditional machining. Dissipation of heat into workpiece which in turn results in enhanced cutting tool wear and damage to the workpiece is the common problems faced in traditional machining of FRPs. Nontraditional machining is favorable to reduce these issues. Abrasive waterjet machining (AWJM) is one of the best choices for machining FRPs. Development in AWJM of FRPs and the current research in this field will be discussed in details. Machining process of FRPs, quality dependents such as surface finish and variable cutting parameters will be addressed. One of main issues in AWJM noise due to high flow rate of water jet will be addressed. The importance of human safety aspects when AWJM is employed will be highlighted. Limitations and challenges in AWJM are presented elaborately.

Abrasive waterjet machining of fiber reinforced composites: A review

Machining of fiber reinforced polymer (FRP) composites is a major secondary manufacturing activity in the aircraft and automotive industries. Traditional machining of these composites is difficult due to the high abrasiveness nature of their reinforcing constituents. Almost all the traditional machining processes involve in the dissipation of heat into the workpiece which can be resulted in damage to workpiece and rapid wear of the cutting tool. This serious issue has been overcome by water jetting technologies. Abrasive waterjet machining (AWJM) is a nontraditional method and one of the best options for machining FRPs. This paper presents a review of the ongoing research and development in AWJM of FRPs, with a critical review of the physics of the machining process, surface characterization, modeling and the newer application to the basic research. Variable cutting parameters, limitations and safety aspects of AWJM and the noise related issues due to high flow rate of water jet will be addressed. Further challenges and scope of the future development in AWJM are also presented in detail.

CN force predication model in milling of carbon fiber reinforced polymers

Fiber reinforced polymers are widely used in the transportation, aerospace and chemical industries. In rare instances these materials are produced net-shape, and secondary processing such as machining and assembly may be required to produce a finished product. Because fiber reinforced polymers are heterogeneous materials, they do not machine in a similar way to metals. Thus, the theory of metal machining is not valid for the analysis of machining of fiber- reinforced composites. Previous attempts in modeling this problem have adopted Merchants theory from metal cutting by assuming that chip formation takes place in a shear plane which inclination angle is determined by the minimum energy principle. This class of models showed that model predictions are valid only for fiber orientations less than 60°. The work presented here focuses on providing predictive models for the cutting forces in unidirectional composites. The models are based on the specific cutting energy principle and account for a wide range of fiber orientations and chip thickness. Results from two forms of non-linear modeling methods, non-linear regression and committee neural networks, were compared. It was found that committee neural networks provide better prediction capability by smoothing and capturing the inherent non-linearity in the data. The model predictions were found to be in good agreement with experimental results over the entire range of fiber orientations from 0 to 180°.

New Trends and Developments in Direct Digital Manufacturing

Direct digital manufacturing (DDM), is advancing rapidly in capability and commercial potential. Directly from CAD data, parts are manufactured without traditional cutting, forming or casting methods. Some of the main developments of the recent past in DDM are discussed in this article. Microstructural and property data will be presented for each type of process, illustrating the benefits and limitations of direct digital manufacturing on various materials, and focusing on emerging and projected applications of metal and ceramic materials by direct digital manufacturing. The review is based on an extensive literature review covering academic publications, company documents and web site information.Copyright

Sustainability of fiber reinforced composites: status and vision for future

Fiber reinforced polymer (FRP) composite products offer many significant environmental benefits such as light weight, superior mechanical properties, extended service life, low maintenance and resistance to corrosion. But until now it has been difficult to compare sustainability of different FRP materials and production for processes. Concern for the environment, both in terms of limiting the use of finite resources and the need to manage waste disposal, has led to increasing pressure to recycle materials. This paper focuses on two issues that must be addressed to ensure continued growth in FRP usage is the disposal of waste generated during product manufacturing and the disposal of the products at the end of their useful life. The major cost drivers for FRPs are labor and raw materials. The use of recycled FRPS offers low-cost raw materials. This paper presents a review of the current status and outlook of FRP composites recycling and re-manufacturing techniques. A future vision for the use of FRP composites with sustainability applications is underway at many university research institutes and in industries. This paper will also state the sustainability problems of fiber reinforced composite products, and potential solutions.Copyright