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Yang, Guobiao
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Test of Inclined Double Beads on Aluminum Sheets

FCA US LLC-Dajun Zhou, Changqing Du, Kaiping Li, Bazzi Rawya
Oakland University-Boyang Zhang, Wan Xu, Guobiao Yang, Junrui Li, Lianxiang Yang
Published 2018-04-03 by SAE International in United States
Draw beads are widely used in the binder of a draw die for regulating the restraining force and control the draw-in of a metal blank. Different sheet materials and local panel geometry request different local draw bead configurations. Even the majority of draw bead is single draw bead, the alternative double draw bead does have its advantages, such as less bending damage may be brought to the sheet material and more bead geometry features available to work on. In this paper, to measure the pulling force when a piece of sheet metal passing through a draw bead on an inclined binder, the AA5XXX and AA6XXX materials were tested and its strain were measured with a digital image correlation (DIC) system. Five different types of double bead configurations were tested. The beads are installed in a Stretch-Bend-Draw-System (SBDS) test device. The clearance between a male and a female bead is 10% thicker than the sheet material. A tensile machine was used to record the pulling force. The comparison of pulling force and strain are reported in…
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Study of Incremental Bending Test on Aluminum Sheets

Aleris-Zhi Deng, John Mcguire, Raj Dasu
FCA US LLC-Changqing Du, Dajun Zhou
Published 2018-04-03 by SAE International in United States
Bendability is one of the most important formability characteristics in sheet metal forming, so it has to be understood for robust aluminum stamping process designs. Crack is one of the major failure modes in aluminum sheet bending. In this study, a new “incremental bending” method is proposed to reduce the risk of bending failure. A novel laboratory test methodology is conducted to test the 5xxx series aluminum sheet bendability with 3D digital image correlation (DIC) measurement system. The designs of test apparatus and test procedure are introduced in this paper. Through the data processing and evaluation of a sequence image acquisition, the major strain histories within the zone of the through thickness crack of test samples are measured. Testing results show that incremental bending is capable of reducing peak strain on the outer surface obviously compared with traditional non-incremental bending. The more step, more movement, the more peak strain reduction. Based on the experimental results, potential applications of incremental bending are discussed and proposed.
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Experimental Validation and Optimization of Computational Methods for High Pressure Fuel Pipe Brazed Joints

Oakland University-Issam Mashal, Boyang Zhang, Xiangning Zhu, Guobiao Yang, Lianxiang Yang
Published 2018-04-03 by SAE International in United States
A V-engine high pressure fuel pipe have experienced several failures during dyno engine validations at brazed joints due to combination of static and dynamic engine loads. The braze fillet experience high local stress concentration with large gradients and it was critical to capture strain contour at this spot to properly understand the failure. Strain gauges was used to measure strain but was incapable of capturing the braze fillet due to the small fillet radius and lack of real estate to install the gauge (braze fillet radius ~ 0.10 mm). A whole field optical experiment method Digital Image Correlation was utilized to successfully captured strain contour at area of interest and results fed back to computational model.In this paper, experimental investigation and theoretical simulation have been carried out to measure and analyze the strain at braze fillets. 3D CAD modeling software Siemens NX was used to design and manufacture a light weight fixture which was used to install the high pressure fuel pipe in uniaxial tension compression machine and perform displacement control compression test. Digital Image Correlation…
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Aluminum Sheet Springback (Side-Wall-Curl) Study

FCA US LLC-Changqing Du, Dajun Zhou
Oakland University-Hao Wang, Elizabeth Lekarczyk, Lianxiang Yang
Published 2017-03-28 by SAE International in United States
Vehicle weight reduction is a significant challenge for the modern automotive industry. In recent years, the amount of vehicular components constructed from aluminum alloy has increased due to its light weighting capabilities. Automotive manufacturing processes, predominantly those utilizing various stamping applications, require a thorough understanding of aluminum fracture predictions methods, in order to accurately simulate the process using Finite Element Method (FEM) software or use it in automotive engineering manufacture. This paper presents the strain distribution of A5182 aluminum samples after punch impact under various conditions by Digital Image Correlation (DIC) system, its software also measured the complete strain history, in addition to sample curvature after it was impacted; therefore obtaining the data required to determine the amount of side-wall-curl (Aluminum sheet springback) present after formation. A thorough understanding of this phenomenon is essential, seeing that any curvature in the part wall can affect quality and sustainability. It is necessary to compensate for this during stamping operations; especially when conducting simulation validation. The data collected during this experimental procedure, in addition to the complete strain…
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A New Measurement of Aluminum Alloy Edge Stretching Limit Based on Digital Image Correlation Method

FCA US LLC-Changqing Du, Dajun Zhou, Yongjun Zhou
Oakland Univ-Xinfeng Shi, Tian Bai, Guobiao Yang, Lianxiang Yang
Published 2016-04-05 by SAE International in United States
In Aluminum Alloy, AA, sheet metal forming, the through thickness cracking at the edge of cut out is one of the major fracture modes. In order to prevent the edge cracking in production forming process, practical edge stretch limit criteria are needed for virtual forming prediction and early stamping trial evaluations. This paper proposes new methods for determining the edge stretching limit of the sheet coupons, with and without pre-stretching, based on the Digital Image Correlation (DIC) technique. A numbers of sets of notch-shaped smaller coupons with three different pre-stretching conditions (near 5%, 10% and fractured) are cut from the prestretched large specimens. Then the notch-shaped smaller coupons are stretched by uniaxial tension up to through edge cracking observed. A dual-camera 3D-DIC system is utilized to measure both coupon face strain and thickness strain in the notch area at the same time. The edge cracking thickness strain limit with the influence of different pre-strain then can be obtained based on the DIC measurements.
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Dimension Study of Punched Hole Using Conical Tipped Punches

FCA US LLC-Dajun Zhou, Changqing Du
Oakland University-Tian Bai, Wan Xu, Junrui Li, Lianxiang Yang
Published 2016-04-05 by SAE International in United States
Dimensional problems for punched holes on a sheet metal stamping part include being undersized and oversized. Some important relationships among tools and products, such as the effect of conical punch tip angle, are not fully understood. To study this effect, sheets of AA6016 aluminum and BH210 steel were punched by punches with different conical tip angles. The test method and test results are presented. The piercing force and withdrawing force when using conical punches were also studied. The results indicate that the oversize issue for a punched hole in a stamped panel is largely due to the combination of the conical tip effect and the stretching-release effect.
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Measurement of Aluminum Edge Stretching Limit Using 3D Digital Image Correlation

FCA US LLC-Changqing Du, Yongjun Zhou, Dajun Zhou
Oakland University-Xin Xie, Xiaona Li, Yi-Hsin Chen, Guobiao Yang, Yaqian Zheng, Bernard Sia, Christina Phillips, Lianxiang Yang
Published 2015-04-14 by SAE International in United States
This paper introduces an industrial application of digital image correlation technique on the measurement of aluminum edge stretching limit. In this study, notch-shape aluminum coupons with three different pre-strain conditions are tested. The edge stretching is proceeded by standard MTS machine. A dual-camera 3D Digital Image Correlation (DIC) system is used for the full field measurement of strain distribution in the thickness direction. Selected air brush is utilized to form a random distributed speckle pattern on the edge of sheet metal. A pair of special optical lens systems are used to observe the small measurement edge area. From the test results, it demonstrate that refer to the notched coupon thickness, pre-tension does not affect the fracture limit; refer to the virgin sheet thickness, the average edge stretch thinning limits show a consistent increasing trend as the pre-stretch strain increased. Test plan, experimental setup, and experimental results are shown in detail in this article.
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The Research on Edge Tearing with Digital Image Correlation

FCA US LLC-Changqing Du, Dajun Zhou, Yongjun Zhou
Oakland University-Xiaona Li, Biyu Ye, Xinfeng Shi, Yaqian Zheng, Junrui Li, Lianxiang Yang
Published 2015-04-14 by SAE International in United States
Material formability is a very important aspect in the automotive stamping, which must be tested for the success of manufacturing. One of the most important sheet metal formability parameters for the stamping is the edge tear-ability. In this paper, a novel test method has been present to test the aluminum sheet edge tear-ability with 3D digital image correlation (DIC) system. The newly developed test specimen and fixture design are also presented. In order to capture the edge deformation and strain, sample's edge surface has been sprayed with artificial speckle. A standard MTS tensile machine was used to record the tearing load and displacement. Through the data processing and evaluation of sequence image, testing results are found valid and reliable. The results show that the 3D DIC system with double CCD can effectively carry out sheet edge tear deformation. The edge tearing test method is found to be a simple, reliable, high precision, and able to provide useful results.
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The Research Progress of Dynamic Photo-Elastic Method

Oakland University-Lianxiang Yang
Oakland University, Tongji University-Guobiao Yang
Published 2014-04-01 by SAE International in United States
With the rapid development of computing technology, high-speed photography system and image processing recently, in order to meet growing dynamic mechanical engineering problems demand, a brief description of advances in recent research which solved some key problems of dynamic photo-elastic method will be given, including:(1) New digital dynamic photo-elastic instrument was developed. Multi-spark discharge light source was replaced by laser light source which was a high intensity light source continuous and real-time. Multiple cameras shooting system was replaced by high-speed photography system. The whole system device was controlled by software. The image optimization collection was realized and a strong guarantee was provided for digital image processing. (2)The static and dynamic photo-elastic materials were explored. The new formula and process of the dynamic photo-elastic model materials will be introduced. The silicon rubber mold was used without the release agent. The epoxy resin sheet or block was solidified at room temperature and could be poured accurately once. The materials had good photodynamic property. (3)The dynamic photo-elastic was applied in engineering. Some research was made by using the…
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Spatial Phase-Shift Digital Shearography for Out-of-Plane Deformation Measurement

SAE International Journal of Materials and Manufacturing

Donghua University; Oakland University-Ping Zhong
Oakland University-Xin Xie, Yaqian Zheng, Xiaona Li, Bernard Sia, Lianxiang Yang
  • Journal Article
  • 2014-01-0824
Published 2014-04-01 by SAE International in United States
Measuring deformation under dynamic loading is still a key problem in the automobile industry. The first spatial phase-shift shearography system for relative deformation measurement is reported. Traditional temporal phase-shift technique-based shearography systems are capable of measuring relative deformation by using a reference object. However, due to its low acquisition rate, the existing temporal phase-shift shearography system can be only used under static loading situations. This paper introduces a digital shearography system which utilizes the spatial phase-shift technique to obtain an extremely high acquisition rate. The newly developed spatial phase-shift shearography system uses a Michelson-Interferometer as the shearing device. A high power laser at 532nm wavelength is used as the light source. A one mega pixels high speed CCD camera is used to record the speckle pattern interference. The spatial frequency carrier is introduced by tilting one of the mirrors in the Michelson-Interferometer. The Fourier Transform method (FT) is used to separate the spectra on spatial frequency domain. The Windowed Inverse Fourier Transform (WIFT) method is then used to evaluate the phase information of the recorded…
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