Defining Materials: Additional Information

The data to define a new material can be obtained through a number of sources. The material supplier/steel company may be able to provide the required data. The material properties are sometimes included on the tag on the individual coils. There are a variety of materials testing companies that can perform tests to obtain this data from a supplied sample of material. In the case of automotive companies, most companies have a standard spec. for each type and grade of material. Stampers/die shops may be able to get the data from the customer.

Many material specifications provide a range of values. For the purposes of analysis, it is wise to choose conservative values from within the range. Use the lower end of the scale for n, r values and the higher end for UTS or K-value.

Here is some information (rules) about the material parameters (see Material Parameters for explanations of the terms used here):

1. Young's Modulus (sometimes called Elastic Modulus) and Poisson's Ratio are required for springback calculations. So, depending on which package you have, these values may not be necessary. As long as you are not running springback, they are not required.

2. Yield stress is also only used for springback and incremental.

3. A user defined stress strain curve completely eliminates the need for the UTS or the K-value. If the FLD0 is calculated, this calculation does use the n-value, however the n-value is not used in the process of actually determining the deformation/thinning of the part. So it is only required if you will be using a calculated FLD0 and if you have access to the safety zones plot. The materials database does require that a value be entered for n-value so it is generally good practice to put in the correct value. Also note that the equation for the calculated FLD0 works well for conventional steels, however it will not be accurate for aluminum and some high strength steels.

4. The r-value is always required, even if your defined stress strain curve is being used. This value is not dependant on the stress strain data.

5. When dealing with advanced high strength steels such as DP (dual phase), TRIP (TRansformation Induced Plasticity) and TWIP (TWin Induced Plasticity) steels, best results will be obtained by importing a stress strain curve and FLC (Forming Limit Curve - see below).

For the purposes of analysis, the finite element engine requires the following material properties:

• n-value

• r-value

• Young's Modulus

• Yield Stress

• Poisson's Ratio

Plus one of the following:

• K-Value

• UTS

• User Defined Stress Strain Curve

Below is a summary of the majority of the material codes used in the material database:

• CR = Cold Rolled

• HR = Hot Rolled

• CQ = Commercial Quality

• DQ = Drawing Quality

• DDQ = Deep Drawing Quality

• EDDQ = Extra Deep Drawing Quality

• AK = Aluminium Killed

• IF = Interstitial Free

• BH = Bake Hardening

• HSLAXX = High Strength Low Alloy (usually followed by the Yield in ksi)

• DP = Dual Phase

• TRIP = Transformation induced plasticity

• EG = Galvanized

• HD = Hot Dipped

• GA = Galvanneal

• HSS = High Strength Steel

• Mart = Martensitic steel

Some functionality may be dependent on the product package. Contact your Reseller if you require a license.