《汽车设计与维修人员培训课件汽车的设计工艺》由会员分享，可在线阅读，更多相关《汽车设计与维修人员培训课件汽车的设计工艺（31页珍藏版）》请在金锄头文库上搜索。
1、,October 2012,Financials Automotive VS,Novelis Automive Europe,Michael Hhnke,Technical Seminar B. General design recommendations for Aluminium,SGM - Novelis,B. Design,B.1 General design recommendations,General considerations If pure strength is needed steel If stiffness is needed Al can fight with s
2、teel by compensating with thickness and still saving weight Depending on applications a compromise between stiffness and strength has to be found. balance between extra cost vs. weight saving: what is affordable?,BIW structure Design criterion,Comparison of Al & Steel Basic properties,Comparison of
3、basic material properties Density: rAl = 1/3 rsteel Reduced mass & lighter weight vehicles Elastic modulus: EAl = 1/3 Esteel Greater elastic deflection compared to steel Equivalent performance at an approximate up gauge of 70% An up-gauge of 80% will give a weight saving of 40% Aluminium has general
4、ly a reduced formability compared to steel Elongation Flanging FLD,Performance aluminium Panel/mild steel panel,Thickness ratio talu/tste,Strength has no influence on the stiffness of a part ! Only gauge or design can influence the stiffness of an aluminium part.,Body in White design Analytic and Em
5、pirical formulae governing main performance criterion,Chang & Justusson SAE Paper 760023, 1976 Based upon mild steel & Aluminium, both with an in-service Proof Stress of 207MPa,Two criterion exist: Stiffness - Flat Sheet E t2 associated with “Oil canning” Stiffness - Flat Sheet E t3 associated with
6、sheet buckling or bending Oil Canning resistance requires a 70% up gauge to give equivalent steel performance with a corresponding 43% mass saving Sheet buckling resistance requires a 45% up gauge to give equivalent steel performance with a corresponding 52% mass saving Note: Proof Stress or UTS has
7、 no influence on sheet stiffness properties Aluminium easily satisfies the stiffness target with a good mass saving compared to any steel grade,BIW Structure Design Criterion for Stiffness Nominally Flat Sheet,Two different criterion exist: Stiffness = bending deflection ( E (D+t)3-D3 ) Stiffness =
8、Torsion angular rotational ( G (r+t)4-r4 ) Where G is the Modulus of Rigidity For same size of box section, aluminium will require a 186% up-gauge compared to steel to give the same bending behaviour This will result in no mass saving compared to steel Aluminium requires an increased box section siz
9、e vs steel to save mass A 20% increase in section depth D requires a 90% up-gauge, for equivalent steel perfomance, giving a mass saving of 25%,BIW Structure Design Criterion for Stiffness Box sections and tubes,Based on Steel Proof stress of 300MPa & gauge of 0.7mm,It is first necessary to satisfy
10、panel stiffness, (suitable design of the inner panel, use of feature lines, etc.),If panel stiffness is exceeded, then panel may be down gauged on basis of local dentability Higher in-service strength allows reduced panel gauges,Outer skin panels design criterion Stiffness and local dentability,Loca
11、l Dentability for outer skins (In-service proof stress x gauge1.8),Flat panel stiffness Et2 or Et3 Esteel 200 GPa Ealuminium 70 GPa,E = material Youngs modulus t = gauge of the panel,Aluminium panel can catch up stiffness of steel panel: by increasing the gauge by modifying the design (example: char
12、acter lines),6xxx aluminium for automotive applications Stiffness considerations,Aluminium panel can catch up stiffness of steel panel: by increasing the gauge by modifying the design (example: character lines),Stiffness increase by five times compared to flat panel,Effect on the stiffness introduce
13、d by the asymmetric embossments,Aluminium for automotive applications Stiffness considerations also for structure and inner parts,Compared to point joining , linear joining increases the stiffness of assembled parts:,Linear joining increases stiffness through box effect ,Aluminium for automotive app
14、lications Stiffness considerations also for structure and inner parts,Aluminium Technology Design for Hem Flanging,Reduce radius reduce gap between 2 parts,Proposed Door Handle Pocket .,Final Design.,General rules for stamped panels design,Panel curvature: Limit depth Open round corners,Feature adde
15、d liftgate inner seal surface,Inner panels: Avoid unsupported metal in areas of compressive stresses during forming to prevent wrinkling,General rules for stamped panels design,Copyright 2007 Novelis Switzerland SA,Existing Aluminium Light Weight Doors,No frame DC CL One-piece cast-Mg inner panel Al
16、 sheet outer panel No frame BMW Z8 Al die casting + extrusion inner Al sheet outer panel Frame Espace Assembly of sheet and extrusion No frame BMW 6er Al sheet 5182 inner Ac121 outer Audi A6 Frame Door inner/Door inner outer/Door outer,Copyright 2007 Novelis Switzerland SA,DC CL Mix of Mg and Al,Advantages Inner panel with integrated functions Complex design of inner panel Disadvantages Pre-painted inner panel to preve
