One of the goals of PDM is to allow files to be stored in a central location, but when they are used, to move these files to the local computer — not just moving files to the LAN, but the actual computer of the user. By having all the files stored centrally, and a database with software managing the revisions, this complex choreographed dance with large amounts of data works far better than manual file management; multiple individuals either are copying files in and out of a central location or are all working on the files directly from the network folders.Working on network folders presents immense risks — overwriting data does not have an undo option. In addition, the delete function does not have a recycle bin. When you manage mission critical company design data on a network without these safety net mechanisms, you are taking unnecessary risks. A PDM system eliminates these risks and automates many other error-prone file anagement tasks, including revision management, document ownership, access to design documentation for the entire company, and security/traceability.( Solidworks Administiration, Matt LOMBARD, John Wiley & Sons, 2009, p.30-31)
Object-Oriented Models
An Object-Oriented(OO) model organizes a system around real-world objects, or conceptual objects, that exist in the user's world, as opposed to functions and data that are split apart. A real-world object, an entity that exists within the application domain, is defined in terms of its responsibilities (behavior), its data (attributes), and its relationships to other objects. All functions of the object are encapsulated (hidden) in the details of the object itself. Therefore, when functional changes are required, they are made within the object, causing little or no disruption to the rest of the model. To utilize the modified or added functions in an object, the remaining objects in the model can be provided with an interface.
The goal of a good object-oriented model is to have self-sufficient objects. This type of object is capable of initiating itself and possesses the intelligence to manage itself through several states, to provide its functional responsibility in the model. (Quality Software Project Management, Robert T. Futrell; Donald F. Shafer; Linda I. Safer, Prentice Hall, 2002, chapter 22)
Low-Cycle Fatigue
The cyclic loads are relatively high, significant amount of plastic strain are induced during each cycle, and short lives or low numbers of cycles to failure are exhibited if these relatively high loads are repeatedly applied. This type of behavior has been commonly called low-cycle fatigue or, more recently, cyclic strain-controlled fatigue. The transition from low-cycle fatigue behavior to high-cycle fatigue behavior generally occurs in the range from about 10^4 to 10^5 cycles, and many investigators now define the low-cycle fatigue range to be failure in 50000 cycles or less. ( Failure of Materials In Mechanical Design, Jack A. COLLINS, John Wiley & Sons, 1993, Second Edition, p.393 )
High-speed automated assembly utulizes transfer mechanisms designed specially for assembly. Two examples of such assembly are the rotary indexing machine and in-line indexing machine in which individual assembly is carried out on products that are indexed for proper positioning during assembly.(Manufacturing Engineering and Technology, Serope Kalpakjian, Steven R. Schmid, Prentice Hall, 5th Edition , p.1181)
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