Expansion equal channel angular extrusion (Exp-ECAE) is a severe plastic deformation (SPD) operation for processing bulk materials. In the current study, AA7075 Al was SPD-processed by expansion equal channel angular extrusion (Ex-ECAE) at various temperatures and ram velocities. Then, using split Hopkinson pressure bar (SHPB), the severely deformed products were compressed at room temperature and strain rates of 0.1~3000 s-1. Both the strain rate sensitivity (SRS) and the apparent activation volume (AAV) were determined for all deformed samples. The results revealed that the Ex-ECAE operation has noticeably increased the SRS. The tensile strength at a strain rate of 3000 s-1 was 6 times increased by conducting Ex-ECAE at 100 °C and with a ram velocity of 7 mm/min. Ex-ECAE was also capable of considerably decreasing the AAV. The results showed the yield stress of both the Exp-ECAE and the annealed samples increased with increasing the strain rate. Also, the results showed that after the Exp-ECAE process, the AAV reached to 6.3 b3 from the initial values of 118.5 b3 in the annealed state. پرونده مقاله

This paper presents a control model of the hydroforming and the dual hydroforming process of a tube. The theoretical part includes calculations to measure the change in tube thickness through the developed process. The hydroforming and the dual hydroforming processes are simulated in the SOLIDSIMULATION software and the static and the dynamic simulations are modeled. The obtained results for the T-shape and the X-shape dies are compared and investigated. Moreover, the developed software in MATLAB calculates the process parameters. The inputs of the developed software are the maximum internal pressure and the axial feed that could be adjusted with linear and non-linear functions. Furthermore, the material of the tube, as well as the tube’s parameters, such as length, thickness, and radius, must to be given to the software. However, the properties of the tube could automatically support the CAD model. The software-generated results are the applied stress, displacement, and the energy through the process. This paper deals with the control strategy model developed in thesoftware packages. The obtained results are then subsequently compared with those of several experiments. پرونده مقاله

Sandwich panel with central core honeycomb aluminum as one of the main shielding structures because of their high strength-to-weight ratio and improved energy absorption capacity, has been attracted the attention of many researchers and practitioners in recent years. This paper initiates and presents a new type of central core honeycomb formed by hydroforming process. The study is augmented by a numerical and experimental work on flexural behavior of sandwich panel structures made of aluminum alloy and different cores such as aluminum, polyurethane foams, PVC, silicone and carbon fiber. Firstly a numerical simulation by ABAQUS software was run, then prepared samples were tested and related force-displacement diagrams were depicted from results. Comparing the corresponding diagrams obtained from simulation with that of the results of experimental investigation, high flexural strength of the sandwich panels with proposed honeycomb core relative to a three-layer sheet as well as a very high flexural strength of suggested sandwich panel with honeycomb core filled with carbon fiber against other samples of honeycomb was observed. Finally, comparing the experimental results with numerical simulations indicates acceptable conformity. پرونده مقاله

در این مقاله برای اولین بار فرآیند هیدروفرمینگ لوله‌های یک، دو و سه‌لایه توسط روش اجزای ‌محدود و در نرم‌افزار ABAQUS/Explicit 6.10 شبیه‌سازی و بین فرآیندها مقایسه انجام شده است. در هر سه مدل، ابعاد هندسی، مواد و پارامترهای ورودی فرآیند یکسان نگه ‌داشته شد تا بتوان پارامترهای خروجی (ارتفاع انشعاب و کاهش ضخامت) را مورد مقایسه قرار داد. برای صحه‌گذاری نشان داده شد که نتایج مدل‌سازی اجزای‌محدود و نتایج آزمایشات تجربی دارای هم‌خوانی مناسبی هستند. در مقایسه بین فرآیندها، مشخص شد که در حالت‌های دو و سه‌لایه نسبت به حالت تک لایه ارتفاع انشعاب کم‌تر، درصد کاهش ضخامت، بیش‌تر و عیب چروک‌خوردگی و کمانش بحرانی‌تر می‌گردد. پرونده مقاله

Tube hydroforming (THF) process is used to produce the complex components from the initial cylindrical tubes. In this paper, T- shape component was formed using a tube hydroforming machine and the residual stresses of hydroformed tube was determined by hole drilling method. Subsequently, the thickness distribution and residual stresses of final tube were investigated using experimental and finite element (FE) methods. The results represented the top of the protrusion has the minimum thickness, whereas the maximum thickness appears in the bottom zone of T-shape tube. The FE results showed that the maximum principal stress in the middle part of piece has own maximum value while the maximum value of minimum principal stress is located in the top of protrusion and the fillet transition region of the protrusion. It is found that the value of residual stress, protrusion height and thickness distribution in simulated results were in good agreement with the experimental results. پرونده مقاله

Development of new technologies and combined with creativity and innovation, plays the fundamental role in developing of any community′s value. Thus, in this research the design and production of hydroforming device was introduced. One of the best and most efficient technologies in the world of metal forming is wind turbine blade producing with hydroforming method which seems as an innovative manner in this field. The aim of this paper is design a small wind turbine blade. Application of this blade is for spaces with size limitation and building large-scale wind turbines. The first step of design process involves choosing and determining the airfoil blade wind turbine, distributing along the radius, angle of the airfoil and chording length distribution along the radius. Turbine blades modeled in CATIA software and transferred to finite element software, ABAQUS. Critical blades points under the hydrostatic pressure have been identified and outputs such as displacement, Von Misses stress obtained from hydroforming simulation process. In the final stage, after ensuring the software outputs blade has been modeled and produced. پرونده مقاله