UltraLight Steel Auto Body - Final Report - American Iron & Steel ...

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280 MPa 2.1 Materials 210 MPa ULSAB Final Report 350 MPa 2.1.1 High strengh steel Mild Steel Steel Sandwich UHSS 420 MPa Materials usage 2. Materials and Processes The UltraLight Steel Auto Body (ULSAB) design called for the application of some steel thicknesses and grades currently available but not commonly used in automotive bodies, as well as the use of advanced manufacturing processes. Steel is the most recycled material in the world, and all steel chosen for the ULSAB structure is recyclable. Steel specifications for the body were chosen to meet mass, performance and safety goals. In their effort to optimize the best attributes of steel in this project, PES engineers specified unusually large percentages of high and ultra high strength steels and steel sandwich material. They also called for the use of hydroforming and tailored blanking. Conventional Blank Stamping Sheet Hydroforming Tubular Hydroforming Miscellaneous Steel Sandwich Stamping Tailored Blank Stamping Processes usage These materials and advanced processes enabled the design engineers to consolidate functions in fewer parts, resulting in mass savings and improved performance. ULSAB uses high strength steel and ultra high strength steel for more than 90 percent of the body structure. ULSAB defines high strength steel as yield strength 210 through 550 MPa and ultra high strength steel as yield strength above 550 MPa. Material thicknesses range from 0.65 mm to 2.00 mm. High and ultra high strength steels were used where the design required certain crash and strength characteristics. For high and ultra high strength steel parts, ULSAB used bake-hardenable steels, isotropic steels, high strength interstitial free steels, transformation induced plasticity steels and dual phase steels. Ultra high strength steel was used for most of the lower crossmembers. 15
16 2.1.2 Tailored blanks One challenge posed by these steels is that they form differently from the mild steel to which many component fabricators are accustomed. High strength steel stampings have greater springback and requires different draw angles so each different grade must be treated by the design engineer and manufacturing engineer as a unique material. Thickness usage in ULSAB is illustrated in the chart below. Nearly half of ULSAB’s mass consists of parts using tailored blanks, which promote smooth load flow, reducing structural discontinuities and allowing for the combination of thicker and higher strength materials within the same part. Tailored blanking enables the design engineer to accurately situate the steel within the part precisely where its attributes are most needed. While this benefit results in improved crash performance, it also leads to weight reduction because it allows the design engineer to remove mass that does not contribute to performance. Tailored blanks also reduce the total number of parts, which leads to the reduction of dies needed for part stamping and the reduction of costs associated with those dies. Likewise, they reduce the number of spot welds and promote improved dimensional accuracy due to reduction in assembly steps. ULSAB’s body side outer is one of several parts that employs a fully laser welded tailored blank with different thicknesses and grades of steels. It employs a one-piece design which includes the complete body side ring as well as the rear quarter. This part was designed for weight savings - through elimination of reinforcements in the body side assembly - and structural performance. It provides exact door fit and also leads to cost savings. ULSAB Final Report
Page 2 and 3: UltraLight Steel Auto Body Final Re
Page 4 and 5: Contents Preface v Introduction vii
Page 6: Preface One of the challenges in re
Page 9 and 10: viii Validation Results During the
Page 12 and 13: 1.1 Benchmarking ULSAB Final Report
Page 14 and 15: 1.2 Design philosophy and architect
Page 16 and 17: ULSAB package drawing front view UL
Page 18 and 19: 1.5 Material selection The selectio
Page 20 and 21: Steel sandwich material was chose f
Page 22 and 23: ULSAB parts list Material Material
Page 24 and 25: ULSAB parts list (cont.) Material M
Page 28 and 29: Tailored blank usage Tailored blank
Page 30 and 31: 2.2 Processes 2.1.3 Steel sandwich
Page 32 and 33: 2.2.2 Assembly laser welding Sheet
Page 34 and 35: 3.1 Early involvement 3.2 Tooling 3
Page 36 and 37: Floor complete assembly: the rear r
Page 38 and 39: ULSAB Final Report 3.5.2 Adhesive b
Page 40 and 41: 4.1 Validation 4.2 CAE Analysis 4.
Page 42 and 43: ULSAB Final Report All simulations
Page 44 and 45: ULSAB Final Report The offset barri
Page 46 and 47: ULSAB Final Report Analysis was set
Page 48 and 49: ULSAB Final Report Side impact set
Page 50 and 51: 4.3 Physical testing ULSAB Final Re
Page 52 and 53: Frequency Hz Model Analysis ULSAB S
Page 54 and 55: 5. Economic Analysis Although light
Page 56 and 57: 5.3 Model scope 5.4 ULSAB results U
Page 58 and 59: 5.4.3 Investments 5.5 Sensitivity a
Page 60 and 61: Comparison of ULSAB with Year 2000

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