Page 47 - MetalForming April 2020

SOFTWARE, SENSORS AND CONTROLS
June 22-23, 2020 Schaumburg (Chicago), IL
MetalForming magazine and the Precision Metalforming Association (PMA) offer providers of ERP/MRP software, sensors and controls an exclusive opportunity to discuss the Internet of Things (IoT) and plant- floor connectivity with engineers, managers and other team members representing metal-stamping and fabricating companies.
Conference activities include:
• Technology demonstrations by
leading suppliers;
• Presentations describing
successful IoT projects at metalforming and fabricating facilities; and
• Keynote presentations on IoT technology developments and implementation trends.
Visit metalformingmagazine.com/IOT for more information.
6363 Oak Tree Blvd. Independence, OH 44131 216/901-8800 www.metalformingmagazine.com
Our Sponsors:
...with support provided by the Control System Integrators Association (CSiA)
Cutting Edge
6000 5000 4000 3000 2000 1000
0 0.6
6000 5000 4000 3000 2000 1000
0 0.6
Hard Brass, No. 18 Gage. Average Breaking Load, 3000 lb. Average Cupping, 0.26 in.
200 150 100
50
0.5 0.4
0.3 0.2
0.1 0
Soft Brass, No. 18 Gage. Average Breaking Load, 5600 lb. Average Cupping, 0.58 in.
DP600 - t 0
= 1mm
0.5 0.4
Cupping Height [in.]
00 5 10 15 20 25 30 35 Dome Height (hd) [mm]
(b)
0.3 0.2 0.1 0 (a)
Fig. 3—Dome height vs. pressure curves: (a) from Olsen’s paper in 1920, (b) from my paper in 2011.
σε1 σ2Rb
R90
σun(90o) b
(a)
(b)
(c)
ε
ε2
σ σun(0o) σ1
R0
Fig. 4—Metal forming simulation requires three graphs: (a) the true stress/true strain curve; (b) forming limit curve; and (c) yield locus. The blue points and curves illustrate what data the bulge test can add.
in several finite-element softwares. An additional reason to use DIC:
the ISO standard requires it.
How DIC Affects the Bulge Test
First of all, DIC almost killed the need for the bulge test, since gathering true stress data at high strains used to represent one of the most important reasons to conduct a bulge test (Fig. 4a). Now, we can gather this data when performing a tensile test with DIC.
Other uses for the bulge test:
With DIC, we can use the bulge test to measure failure strain, and simply put one of the points onto the forming limit curve (Fig. 4b).
We can measure two new material properties: biaxial anisotropy (Rb)and biaxial yield stress (σb), in order to cal- culate advanced yield locus such as Corus-Vegter or the simplified version, Vegter Lite (Fig. 4c). I will write in more detail about these advanced material models in future MetalForming maga- zine columns.
In my next column (June 2020 Met- alForming), I will discuss using DIC for developing a forming limit curve.
MF
Come hear Dr. Eren Billur speak at the 3rd Metal Forming Technology Day, in Bursa, Turkey. Visit www.billur.com.tr/ meftech for more information.
Literature and further reading:
Olsen, T. Y. “Ductility Testing Machines.” Proc. Amer. Soc. Test. Mach 20.II (1920): 398.
Vegter, H., ten Horn, C., & Abspoel, M. (2009). The corus-vegter lite material model: simplifying advanced material modelling. International Journal of Material Forming, 2(1), 511.
Billur, E., Demiralp, Y., Groseclose, A. R., Wadman, B., & Altan, T. (2011, September). Factors Affecting the Accu- racy of Flow Stress Determined by the Bulge Test. In International Conference on Technology of Plasticity, Aachen, Germany.
ISO 16808:2014, Determination of biaxial stress-strain curve by means of bulge test with optical measuring systems.
www.metalformingmagazine.com
MetalForming/April 2020 45
Load [lb.]
Pressure (P) [bar]