150 research outputs found
Numerical modeling of the thermal contact in metal forming processes
Heat flow across the interface of solid bodies in
contact is an important aspect in several engineering applications.
This work presents a finite element model for the
analysis of thermal contact, which takes into account the
effect of contact pressure and gap dimension in the heat
flow across the interface between two bodies. Additionally,
the frictional heat generation is also addressed, which
is dictated by the contact forces predicted by the mechanical
problem. The frictional contact problem and thermal
problem are formulated in the frame of the finite element
method. A new law is proposed to define the interfacial heat
transfer coefficient (IHTC) as a function of the contact pressure
and gap distance, enabling a smooth transition between
two contact status (gap and contact). The staggered scheme
used as coupling strategy to solve the thermomechanical
problem is briefly presented. Four numerical examples are presented to validate the finite element model and highlight
the importance of the proposed law on the predicted
temperature.The authors gratefully acknowledge the financial
support of the Portuguese Foundation for Science and Technology
(FCT) under the project PTDC/EMS-TEC/1805/2012 and by
FEDER funds through the program COMPETE Programa Operacional
Factores de Competitividade, under the project CENTRO-07-0224-
FEDER-002001 (MT4MOBI). The second author is also grateful to the
FCT for the postdoctoral grant SFRH/BPD/101334/2014. The authors
would like to thank Prof. A. Andrade-Campos for helpful contributions
on the development of the finite element code presented in this work.info:eu-repo/semantics/publishedVersio
Effect of Weld Schedule on the Residual Stress Distribution of Boron Steel Spot Welds
Press-hardened boron steel has been utilized in anti-intrusion systems in automobiles, providing high strength and weight-saving potential through gage reduction. Boron steel spot welds exhibit a soft heat-affected zone which is surrounded by a hard nugget and outlying base material. This soft zone reduces the strength of the weld and makes it susceptible to failure. Additionally, different welding regimes lead to significantly different hardness distributions, making failure prediction difficult. Boron steel sheets, welded with fixed and adaptive schedules, were characterized. These are the first experimentally determined residual stress distributions for boron steel resistance spot welds which have been reported. Residual strains were measured using neutron diffraction, and the hardness distributions were measured on the same welds. Additionally, similar measurements were performed on spot welded DP600 steel as a reference material. A correspondence between residual stress and hardness profiles was observed for all welds. A significant difference in material properties was observed between the fixed schedule and adaptively welded boron steel samples, which could potentially lead to a difference in failure loads between the two boron steel welds
Characterization of the flow behavior of deep drawing steel grades in dependency of the stress state and its impact on fea
Animal experimental studies on deformation of the septum cartilage after unilateral mucous membrane detaching
Prediction of springback during indirect hot press forming through tensile test with simultaneous cooling
Study of temperature on microstructure and mechanical properties on Fe/Al joint in laser-assisted friction stir welding
Modeling of the plastic characteristics of AA6082 for the friction stir welding process
Focus of this paper is to model the plastic forming behavior of AA6082, in order to
develop the numerical FE analysis of the friction stir welding processes and the simulation of
subsequent forming processes. During the friction stir welding process, the temperatures reached
can range up to 500 \ub0C and have a fundamental role for the correct performance of the process, so
the material data has to show a temperature dependency. Because of the tool rotation a strain rate
sensitivity of the material has to be respected as well. In this context, the general material
characteristics of AA6082 were first identified for different stress states. For the uniaxial state the
standard PuD-Al used in the automotive industry was applied, for the shear state the ASTM B831-
05 was used and for biaxial states the ISO 16842 was exploited. To characterize the plastic flow
behavior of the AA6082 at elevated temperatures, tensile tests were performed according to DIN
EN ISO 6892-2 from 25 \ub0C to 500 \ub0C with a strain rate from 0.1 s-1 up to 6.5 s-1
Improved Sheet Bulk Metal Forming Processes by Local Adjustment of Tribological Properties
Artificial Intelligence in manufacturing: State of the art, perspectives, and future directions
Data-driven inline optimization of the manufacturing process of car body parts
The manufacturing process of car body parts needs to be adaptable during production because of fluctuating variables; finding the most suitable settings is often expensive. The cause-effect relation between variables and process results is currently unknown; thus, any measure taken to adjust the process is necessarily subjective and dependent on operator experience. To investigate the correlations involved, a data mining system that can detect influences and determine the quality of resulting parts is integrated into the series process. The collected data is used to analyze causes, predict defects, and optimize the overall process. In this paper, a data-driven method is proposed for the inline optimization of the manufacturing process of car body parts. The calculation of suitable settings to produce good parts is based on measurements of influencing variables, such as the characteristics of blanks. First, the available data are presented, and in the event of quality issues, current procedures are investigated. Thereafter, data mining techniques are applied to identify models that link occurring fluctuations and appropriate measures to adapt the process so that it addresses such fluctuations. Consequently, a method is derived for providing objective information on appropriate process parameters
- …