Enhancement on deformation uniformity of double curvature
shell by hydroforming process and curved blank-holder surface
Received: 18 October 2016 /Accepted: 13 March 2017 / Published online: 23 March 2017
Springer-Verlag London 2017
Abstract To manufacture a component with uniform defor-
mation as well as homogeneous properties to fulfill the need
of good consistency in service, both tool geometry and
forming method were taken into account on the forming of
double curvature shell. Experimental setups with planed and
curved blank-holder surfaces combined with hydroforming
process were performed on the evaluation of stain and thick-
ness distribution compared with conventional deep drawing
process. The average strain and its standard deviation on the
formed shell were calculated as the indicators of whole strain
level and strain uniformity. The results show that the most
homogeneous strain, tensile strength, and micro-hardness
can be achieved by the combination of hydroforming process
and curved blank-holder surface.
Double curvature shell
The production of complex curved surface panels presents a
unique challenge for the manufacturing industry on the de-
mand of weight reduction and good properties in service.
High strength lightweight materials and complicated geomet-
rical structures are designed and applied to fulfill the need.
Double curvature shell fabricated with aluminum alloy sheet
is a kind of very typical complicated structure usually applied
in the manufacturing domains such as aerospace, air-craft, and
car-body industries, etc. .
By now, much attention had been paid on the geometrical
precision control of double curvature shell in the previous
investigations. Borah et al.  studied the springback behavior
after press forming by rigid tools and the changing on the final
curvature radius of the double curvature panel on large pres-
sure vessel. Zhang et al.  investigated the effect of aging
temperature, time, and internal stress on geometrical shape of
double curvature shell during creep age forming process and
pointed out there is difference in the two curvature directions
of the formed sample. Zhang et al. proposedanalgorithm
for springback compensation during the multi-point forming
process of double curved plate. Relatively small errors and
satisfied processing precision could be obtained combining
theoretical analysis, numerical simulation, and forming exper-
iment. However, these components are difficult to be
manufactured in consistent shape with high precision as well
as in good properties by traditional forming processes. The
complicated stress and strain applied on different region and
residual deformation distribution after forming procedure will
result inhomogeneous texture on the microstructure, and will
bring non-uniform mechanical properties on the components
as a result [5, 6].
Since the depth of double curvature shell is usually
very shallow and the curvature radius is different, the
(a) Both tool geometry and forming method were considered on
uniformity of strain and property.
(b) Hydroforming process has great effect both on whole strain level and
strain uniformity with planed and curved blank-holder.
(c) Both the whole strain level and the strain uniformity can be improved
by hydroforming process with curved blank-holder.
* Wei Liu
National Key Laboratory for Precision Hot Processing of Metals,
Harbin Institute of Technology, Harbin 150001, China
School of Materials Science and Engineering, Harbin Institute of
Technology, Harbin 150001, China
Capital Aerospace Machinery Company, Beijing 100076, China
Int J Adv Manuf Technol (2017) 92:1913–1922