Friday, June 13, 2008
Wednesday, June 04, 2008
Monday, May 26, 2008
Saturday, August 11, 2007
Circle Grid Analysis Maximum Deformation Zone
Yanwu Xu has an article in the August 2007 issue of Metalforming Magazine. This article is based on his book "Modern Formability: Measurement, Analysis, and Applications.
This article details manually measuring deformed circles in the grid to find the ellipse of maximum deformation. This then is the center of the Deformation Zone.
I remember Eric Kam said he spent a number of years doing circle grid analysis. This article answered a few questions I had and gave me some new ones.
http://www.metalformingmagazine.com
http://www.hansergardner.com
__________________
James G Peck
http://autobodymfg.blogspot.com
This article details manually measuring deformed circles in the grid to find the ellipse of maximum deformation. This then is the center of the Deformation Zone.
I remember Eric Kam said he spent a number of years doing circle grid analysis. This article answered a few questions I had and gave me some new ones.
http://www.metalformingmagazine.com
http://www.hansergardner.com
__________________
James G Peck
http://autobodymfg.blogspot.com
Tuesday, June 05, 2007
Automation determines BIW consistency: News from Mike Page - editor's feature articles
This discusses Bentley body assembly.
Friday, May 25, 2007
Monday, February 05, 2007
Saturday, December 30, 2006
formability
Sheet metal formability: sheet metal formability can be evaluated by a variety of mechanical tests.
Publication Date: 01-AUG-02
Publication Title: Advanced Materials & Processes
Format: Online - approximately 2424 words
Author: Gedney, Richard
Article Price: $4.95
Subscription to Research: $89.95/month (learn more)
NOTE: All illustrations and photos have been removed from this article.
Description Formability is a measure of the amount of deformation a material can withstand prior to fracture or excessive thinning. Sheet metal forming ranges from simple bending, to stretching, to deep drawing of complex parts (Fig. 1). Therefore, determining the extent to which a material can deform is necessary for designing a reproducible forming operation.
Because mechanical properties greatly influence formability, and forming properties may vary from coil to coil, it is essential to test incoming sheet material. However, the outcome of a forming process depends on both material characteristics and process variables such as strain, strain rate, and temperature. In fact, stress and strain fields are so diverse during a forming process that no single test can reliably predict the formability of materials in all situations.
Material properties that have a direct or indirect influence on formability and product quality are Ultimate Tensile Strength, Yield Strength, Young's Modulus, Ductility, Hardness, the Strain Hardening Exponent, and the Plastic Strain Ratio. All of these parameters can be determined by testing a specimen cut from the blank. This article explains the meaning of each of these tests, describes how they are carried out, and provides equations to calculate important values.
Tensile tests
A graphical description of the amount of deflection under load for a given material is the stress-train curve. The stress-strain curve is generated by pulling a metal specimen in uniaxial tension to failure. ASTM E8/E8M Standard Test Methods for Tension Testing Metallic Materials governs the methods for the determination of Yield Strength, Ultimate Tensile Strength, Percent Elongation at Fracture, and Reduction of Area, the latter two being measures of ductility.
Engineering stress S is found by dividing the load P at any given time by the original cross sectional area [A.sub.o] of the specimen.
S = P/[A.sub.o] Eq. 1
Engineering strain e is calculated by dividing the elongation of the gage length of the specimen L by the original gage length [L.sub.o].
E = [delta]L/[L.sub.o], = (L - [L.sub.o])/[L.sub.o] Eq. 2
Figure 2 depicts a typical stress-strain curve. The shape and magnitude of the curve depend on the type of metal. Point A represents the proportional limit of a material. A material loaded in tension beyond point A, when unloaded will exhibit permanent or plastic deformation. The proportional limit is often difficult to...
Publication Date: 01-AUG-02
Publication Title: Advanced Materials & Processes
Format: Online - approximately 2424 words
Author: Gedney, Richard
Article Price: $4.95
Subscription to Research: $89.95/month (learn more)
NOTE: All illustrations and photos have been removed from this article.
Description Formability is a measure of the amount of deformation a material can withstand prior to fracture or excessive thinning. Sheet metal forming ranges from simple bending, to stretching, to deep drawing of complex parts (Fig. 1). Therefore, determining the extent to which a material can deform is necessary for designing a reproducible forming operation.
Because mechanical properties greatly influence formability, and forming properties may vary from coil to coil, it is essential to test incoming sheet material. However, the outcome of a forming process depends on both material characteristics and process variables such as strain, strain rate, and temperature. In fact, stress and strain fields are so diverse during a forming process that no single test can reliably predict the formability of materials in all situations.
Material properties that have a direct or indirect influence on formability and product quality are Ultimate Tensile Strength, Yield Strength, Young's Modulus, Ductility, Hardness, the Strain Hardening Exponent, and the Plastic Strain Ratio. All of these parameters can be determined by testing a specimen cut from the blank. This article explains the meaning of each of these tests, describes how they are carried out, and provides equations to calculate important values.
Tensile tests
A graphical description of the amount of deflection under load for a given material is the stress-train curve. The stress-strain curve is generated by pulling a metal specimen in uniaxial tension to failure. ASTM E8/E8M Standard Test Methods for Tension Testing Metallic Materials governs the methods for the determination of Yield Strength, Ultimate Tensile Strength, Percent Elongation at Fracture, and Reduction of Area, the latter two being measures of ductility.
Engineering stress S is found by dividing the load P at any given time by the original cross sectional area [A.sub.o] of the specimen.
S = P/[A.sub.o] Eq. 1
Engineering strain e is calculated by dividing the elongation of the gage length of the specimen L by the original gage length [L.sub.o].
E = [delta]L/[L.sub.o], = (L - [L.sub.o])/[L.sub.o] Eq. 2
Figure 2 depicts a typical stress-strain curve. The shape and magnitude of the curve depend on the type of metal. Point A represents the proportional limit of a material. A material loaded in tension beyond point A, when unloaded will exhibit permanent or plastic deformation. The proportional limit is often difficult to...
Friday, November 24, 2006
Friday, June 30, 2006
Wednesday, May 31, 2006
Sunday, May 28, 2006
Handheld Scanner for vehicle body reverse engineering
The May/June 2006 issue of Time-Compression Technologies,
www.timecompress.com, discusses the use of a handheld self-positioned
laser scanner to scan a vehicle body to produce a 3D CAD model of the
vehicle body. The vehicle scanned was the T-Rex manufactured in Quebec
for the purpose of doing FEA and using CMM's.
www.handyscan3d.com
www.creaform3d.com
Jim Peck
http://autobodymfg.blogspot.com
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