Search Results for circle grid strain analysis

This article describes strain analysis techniques for troubleshooting formability and process discrepancies throughout a tooling development and production stamping cycle. The techniques include strain calculations of a flat blank, forming limit curve, and forming limit diagram. The article describes the types of strain analysis, namely, thinning strain analysis and circle grid strain analysis. It also provides information on the applications of the thinning strain analysis.

Sheet metal forming operations are so diverse in type, extent, and rate that no single test provides an accurate indication of the formability of a material in all situations. This article presents an overview of types of forming, formability problems, and principal methods of measuring deformation. It reviews the effect of materials properties and temperature on formability. The article provides a detailed discussion on the two major categories of formability tests such as the intrinsic test, including uniaxial tension testing, plane-strain tension testing, biaxial stretch testing, and simulative tests such as bending tests, stretching tests, the Ohio State University test, the drawing test, and stretch-drawing tests. It extends the correlation between simulative tests and materials properties using forming limit diagrams and circle grid analysis, and discusses the improvements to the forming limit diagram technology.

Sheet forming failures divert resources from normal business activities and have significant bottom-line impact. This article focuses on the formation, causes, and limitations of four primary categories of sheet forming failures, namely necks, fractures/splits/cracks, wrinkles/loose metal, and springback/dimensional. It discusses the processes involved in analytical tools that aid in characterizing the state of a formed part. In addition, information on draw panel analysis and troubleshooting of sheet forming failures is also provided.

Steel sheet is widely used for industrial and consumer products, partly because it is relatively strong, easily joined, and readily available at moderate cost. This article discusses the mechanical properties and formability of steel sheet, the use of circle grid analysis to identify the properties of complicated shapes, and various simulative forming tests. The mechanical properties of steel sheet that influence its forming characteristics, either directly or indirectly, can be measured by uniaxial tension testing. The article covers the effects of steel composition, steelmaking practices, and metallic coatings, as well as the correlation between microstructure and formability. A guide to the selection of steel sheet is also included. The formability of steel sheet is related to various microstructural features of the sheet. The article describes some of the forming characteristics of the more commonly used formable grades. It also lists the typical mechanical properties for common grades of hot-rolled and cold-rolled steel sheets.

Statistics are extremely important tools in the operation of press shops, providing numerical process analysis capabilities. The most common use of statistics in the press shop is statistical process control (SPC) that uses statistical techniques such as control charts to analyze a process or its output to enable appropriate actions to be taken to achieve and maintain a state of statistical control. This article discusses the role of statistics in sheet metal forming operations, both in terms of SPC techniques, such as control charting, statistical deformation control, and experimental design, including single-variable studies, multivariable studies, and Taguchi experiments.

This article focuses on the effects of mechanical plasticity on workability; that is, process control of localized stress and strain conditions to enhance workability. It describes the nature of local stress and strain states in bulk forming processes, leading to a classification scheme, including testing procedures and specific process measurements, that facilitate the application of workability concepts. Using examples, the article applies these concepts to forging, rolling, and extrusion processes. The stress and strain environments described in the article suggest that a workability test should be capable of subjecting the material to a variety of surface strain combinations. By providing insights on fracture criteria, these tests can be used as tools for troubleshooting fracture problems in existing processes, as well as in the process development for new product designs.

This article describes grade designations of the various sheet steels used for draw forming. It discusses the specifications associated with most sheet draw forming materials. The article examines the behavior of stress- and strain-based forming limit curve (FLC). It provides a discussion on three separate frictional conditions acting in a draw die. The frictional conditions include the metal passing through a draw bead, the metal clamped in the binder, and the metal sliding across a die radius. The article also explains the basic steps in the vehicle development process. The steps involved in the thought process of direct engineering for formability are also explained. The article places considerable emphasis on the need for the designer to clearly define the die/tooling faces in the computer-aided design (CAD)/computer-aided manufacturing (CAM) system before the data are passed on to the construction functions.

An important activity in metalworking facilities is the testing of raw materials for characteristics that ensure the integrity and quality of the products made. This article reviews the common material parameters that can have a direct or indirect influence on workability and product quality. These include strength, ductility, hardness, strain-hardening exponent, strain-rate effects, temperature effects, and hydrostatic pressure effects. The article also reviews the material behavior characteristics typically determined by mechanical testing methods. It discusses various mechanical testing methods, including the tension test, plane-strain tension test, compression test, plane-strain compression test, partial-width indentation test, and torsion test. Aspects of testing particularly relevant to workability and quality control for metalworking processes are also described. Finally, the article details the various factors influencing workability in bulk deformation processes and formability in sheet-metal forming.

Computational fluid dynamics (CFD) is one of the tools available for understanding and predicting the performance of thermal-fluids systems. This article qualitatively describes the basic principles of CFD. The numerical methods, such as geometry description and discretization, used to solve the CFD equations are discussed. The article also demonstrates the application of CFD to a few casting problems.

This article focuses on the factors that determine the extent of deformation a metal can withstand before cracking or fracture occurs. It informs that workability depends on the local conditions of stress, strain, strain rate, and temperature in combination with material factors. The article discusses the common testing techniques and process variables for workability prediction. It illustrates the simple and most widely used fracture criterion proposed by Cockcroft and Latham and provides a workability analysis using the fracture limit line. The article describes various workability tests, such as the tension test, ring compression test, plane-strain compression test, bend test, indentation test, and forgeability test. It concludes with information on the role of the finite-element modeling software used in workability analysis.

This article is a compilation of definition of the terms related to modeling for metals processing.

This article is a comprehensive collection of terms related to metalworking operations that produce shapes from forging, extrusion, drawing, and rolling operations.

This article reviews the various types of mechanical testing methods, including hardness testing; tension testing; compression testing; dynamic fracture testing; fracture toughness testing; fatigue life testing; fatigue crack growth testing; and creep, stress-rupture, and stress-relaxation testing. Shear testing, torsion testing, and formability testing are also discussed. The discussion of tension testing includes information about stress-strain curves and the properties described by them.

This article focuses on the technology breakthroughs that make forming simulation a routine work throughout the industry. It discusses many forms of the computer-aided engineering (CAE) methodology. The article describes several failure criteria to predict the failure of sheet metal. It explains the numerical procedure for sheet metal forming and reviews the important technical issues in CAE simulations. The article provides information on the applications and process of metal-forming simulation. It also reviews the capabilities of major systems that are popular among sheet metal forming users worldwide.

This article is a compilation of definition of the terms related to simulation of metals processing.

This article begins with a discussion on the criteria for evaluating computer programs for composites structural analysis, including database capabilities, types of engineering calculations supported, interface and operating systems, and technical support. It describes the capabilities of programs, such as CompositePro, ESAComp, and V-Lab that provide a graphical interface, built-in databases, and integrated modules for the different types of analyses. The article reviews the modules of other programs used for composite analysis. The programs include ASCA, CADEC, CoDA, COMPASS, ESDU, LAP, PROMAL, and SACL. The article concludes with information on on-line programs and recourses.

Bending is a common metalworking operation to create localized deformation in sheets (or blanks), plates, sections, tubes, and wires. This article emphasizes on the bending of sheet metal along with some coverage on flanging. It informs that variations in the bending stresses cause springback after bending, and discusses the variables and their effects on springback, as well as the methods to overcome or counteract them. These methods include overbending, bottoming or setting, and stretch bending. The article provides information on elastic bending, non-cylindrical bending, elastic-plastic bending, and pure plastic bending. Sheet metal bendability is a critical factor in many forming operations. The article illustrates the derivation of two relevant bend-ductility equations.