Browsing by Author "Zhang, Weijie"

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    Electrochemical Characteristics of AZ31 Magnesium Alloys with Microarc Oxidation Coating
    (Office of the Vice Chancellor for Research, 2013-04-05) Berman, Alycia; Zhang, Weijie; Zhang, Hanying; Hu, Xinyao
    When considering implantable biomaterials, one possible solution that has arisen in recent years is the use of magnesium alloys due to their excellent mechanical properties. Magnesium alloys have many properties comparable to bone, including strength-to-weight ratio, density, and yield strength. For those reasons, magnesium alloys have been viewed as a promising biomaterial. Unfortunately, magnesium alloys are also prone to corrosion attack. To decrease the corrosion, studies have been taken to find appropriate coatings. One possibility is microarc oxidation (MAO) coating. However, studies have yet to be conducted to determine the corrosion of magnesium alloys with MAO coating. In this study, both MAO-coated and uncoated magnesium alloys will be placed in 0.9% saline solution and simulated body fluid and a time study will be conducted. The corrosion properties will be measured through use of a computer-generated Tafel curve, as well as through optical microscopy of the corrosion over the course of time.When considering implantable biomaterials, one possible solution that has arisen in recent years is the use of magnesium alloys due to their excellent mechanical properties. Magnesium alloys have many properties comparable to bone, including strength-to-weight ratio, density, and yield strength. For those reasons, magnesium alloys have been viewed as a promising biomaterial. Unfortunately, magnesium alloys are also prone to corrosion attack. To decrease the corrosion, studies have been taken to find appropriate coatings. One possibility is microarc oxidation (MAO) coating. However, studies have yet to be conducted to determine the corrosion of magnesium alloys with MAO coating. In this study, both MAO-coated and uncoated magnesium alloys will be placed in 0.9% saline solution and simulated body fluid and a time study will be conducted. The corrosion properties will be measured through use of a computer-generated Tafel curve, as well as through optical microscopy of the corrosion over the course of time.
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    Implementation of re-usable, configurable systems engineering model using product lifecycle management platform
    (2015-08) Zhang, Weijie; El-Mounayri, Hazim; Chen, Jie; Surber, Dan Clifford; Li, Shuning
    Industry is facing the challenge of increasing product complexity while at the same time reducing cost and time in a highly competitive global market. Product Lifecycle Management (PLM) and Systems Engineering have the potential to help companies avoid costly product development and launching, as well as failure during use; these two concepts not only share many common characteristics, but also complement each other. PLM provides an information management system that can seamlessly integrate enterprise data, business processes, business systems and, ultimately, people throughout all phases of the product lifecycle. Systems engineering is an interdisciplinary approach to designing, implementing, evaluating, and managing the complex human-made systems over their life cycle. The same underlying methods that improve management of products and services can be used to organize the framework in which PLM systems are implemented, integrated, and evolved. Though several studies have indicated that adopting Systems Engineering with PLM brings many benefits for industries, implementation of PLM based Systems Engineering with PLM has rarely been conducted. Pattern-Based Systems Engineering (PBSE), a form of Model-Based Systems Engineering (MBSE) based on the use of Systematic Metamodel (S* Metamodel), represents a family of manufacturing system, and is used in the life cycle processes of ISO 15288, was implemented here using TEAMCENTER® PLM software as the platform. More specifically, we have implemented the key portion of the General Production Pattern based on S* Metamodel, and demonstrated the benefit through the manufacturing of oil filter case study. The above implementation have resulted in a powerful systems engineering model in PLM that leverages the capabilities of Teamcenter, to enable an enhanced systems engineering approach. Benefits brought to systems engineering practice include: the ability to capture and reflect stakeholders' requirements and changes in product design process promptly and accurately; the ability of systems engineers to create models quickly and prevent mistakes during modeling; the ability of systems engineers to do their job much easily by using reusable and reconfigurable models; the ability to re-use of previous designs in a new process.
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    RESIDUAL STRESS ANALYSIS OF CERAMIC COATINGS ON BIOCOMPATIBLE MAGNESIUM ALLOYS
    (Office of the Vice Chancellor for Research, 2012-04-13) Zhang, Weijie; Jiang, Zhuoyi; Zhang, Hanyin; Zhang, Jing
    Magnesium and its alloys have gained special interest in medical applica-tions in recent years, as promising biodegradable metallic implant materials, due to their excellent mechanical properties and biocompatibilities. However, magnesium alloys rapidly corrode in human body. Therefore, a dense ceram-ic coating has been produced on the surface of the magnesium alloy through the method of microarc oxidation (MAO), which improves the corrosion re-sistance of the magnesium alloy. The objective of this study is to evaluate the residual stress of the ceramic coating on biocompatible AZ31 magnesium alloy. The corresponding residual stresses with different applied voltages have been examined in this study. An integrated experimental and modeling approach has been employed. Residual stresses attributed to the MgO constituent of the coatings at oxida-tion voltages between 250 V to 350 V have been evaluated by X-ray diffrac-tion (XRD) using sin2ψ method. An analytic model is also used to compute the stress distributions in the coatings. The residual stresses decreased with the increase of the applied voltage. The predicated stresses from the analytic model are in good agreement with the experimental measurements. At 350V, the coating has a uniform surface morphology and the lowest residual stress. This is the optimal voltage in the MAO process to produce the high-quality corrosion resistant coating. The measured stresses using sin2 ψ XRD method in the MgO constituent of the MAO coatings are tensile in nature. The voltage-dependent residual stress has been released during the microarc discharge process, which is attributed to the micro-pores and cracks formed in the coating.