Isotropic Material Testing for Ultra High Strength Steel Enclosures
Verify multi-axial yield limits and planar plastic strain ratios across three sheet axes to prevent catastrophic battery enclosure tearing under crash loads.
ISO 12004-2
Meaning
Global standards for materials testing define the methods for determining forming limit curves of sheet metals. The document known as iso 12004-2 specifies the laboratory procedures for measuring these limits using either dome tests or sheet stretching methods. Sourcing and quality control teams use these curves to evaluate the formability of steel or aluminum sheets before production begins.
This standard provides a consistent basis for comparing different batches of metal from multiple suppliers.
Limit Determination
Forming limit diagrams represent the boundary between safe plastic deformation and the onset of localized necking or failure. The standard outlines how to apply a grid or pattern to the sheet metal prior to deformation. By measuring the changes in the pattern, the maximum strains are calculated.
Optical Measurement
Digital image correlation technology is used to monitor the specimen continuously during the deformation process. This technique measures the localized strain field around the necking zone with high precision. It replaces manual measurement methods and reduces the human error in locating the onset of localized thinning.
Standard Evaluation
Material selection processes for complex automotive body parts rely on the strain limits defined by this procedure. By keeping the stamping strains below the forming limit curve, manufacturers prevent tears and wrinkles. It guarantees that the sourced metals can withstand the required forming operations without failure.