Study on the Static Performance of Prefabricated UHPC-Steel Epoxy Bonding Interface

Prefabricated UHPC-steel composite structure can make full use of the two materials’ mechanical and construction performance characteristics, with super mechanical properties and durability, which has been proved to be a very promising structure. However, using traditional mechanical connectors to connect prefabricated UHPC and steel not only is inconvenient for the prefabrication of UHPC components but also introduces heavy welding work, which is detrimental to the construction speed and antifatigue performance of the composite structure. Bonding UHPC-steel interface with epoxy adhesive is a potential alternative to avoid the above problem. In order to explore the mechanical properties of the prefabricated UHPC-steel epoxy bonding interface, this study carried out the direct shear test, tensile test, and tensile-shear test of the UHPC-steel epoxy-bonded interface (prefabricated UHPC-steel epoxy bonding interface). The results show that the interface failure is mainly manifested as the peeling of the epoxy-UHPC interface and the destruction of part of the UHPC matrix (the failure of the UHPC's surface). In pure shear and pure tension state, the interfacial shear strength is 5.14 MPa and the interfacial tensile strength is 1.18 MPa. In the tensile-shear state, the interfacial shear strength is 0.61 MPa and the interfacial tensile strength is 1.06 MPa. The stress-displacement curves of the interface normal and tangential direction are all in the shape of a two-fold line. The ultimate displacement was within 0.1 mm, showing the characteristics of brittle failure. Finally, a numerical model of the tensile specimen is established based on the cohesive interface element, and the interfacial tensile-shear coupling failure mechanism (tensile-shear coupling effect) is analyzed.

Evaluation of Compression Performance of APM Aluminum Foam-Polymer Filled Pipes Prepared via Different Epoxy Resin Bonding Processes

The composite structurehttp://mts.hindawi.com/update/) in our Manuscript Tracking System and after you have logged in click on the ORCID link at the top of the page. This link will take you to the ORCID website where you will be able to create an account for yourself. Once you have done so, your new ORCID will be saved in our Manuscript Tracking System automatically."?> with aluminum foam not only has the strength and toughness of the dense material but also reduces the weight of the component and increases specific deformation energy absorption performance. In this paper, advanced pore morphology (APM) foam elements are combined with thin-walled circular steel pipes by epoxy-bonding and epoxy foam-bonding processes to prepare composite circular pipes. The direct epoxy-bonding process using epoxy resin refers to coating the surface of APM spheres, whereas the epoxy foam-bonding process involves the mixing of the epoxy resin with the epoxy foaming agent and then coating the surface of APM spheres with this mixed epoxy resin. The compression performances and energy absorption performances were analyzed by quasistatic compression tests. Results indicate that the different bonding modes change the deformation mode of the specimen under compression. The epoxy foam-bonding APM composite pipe has a higher compression load level than the epoxy-bonding APM filled pipe. The epoxy foam-bonding APM composite pipe is superior to the epoxy-bonding APM composite and thin-wall hollow pipe. Hence, the combination of foaming and bonding of epoxy can be used as a new filling process for APM fillers.

An Epoxy Bonding Apparatus for Applications under Extreme Environment

ABSTRACTA number of electrical components and devices work in extreme environment such as high temperature, high pressure, strong vibration, corrosive chemicals, etc. A common practice to protect them is to shield them in materials that are mechanically and chemically resistant to these harsh conditions. In this scenario, epoxy bonding is preferred and it is crucial to have high bonding strength. One example is the acoustic transducers used in oil drilling. The temperature can reach 200 °C and the pressure can reach 140 MPa. The piezoelectric ceramic parts cannot withstand these conditions so different packaging materials are used such as polyether ether ketone (PEEK).Here an epoxy bonding apparatus is presented that has demonstrated ultrahigh bonding strength. Though epoxy resin is degassed before applying, which gets rid of air bubbles generated in the mixing process, there is trapped air when two surfaces are closed together. This trapped air has minuscule effect for applications in ambient environment, but under extreme environment, it compromises the bonding strength majorly. We devised a vacuum system that contains a motorized stage with the bonding parts attached. After the epoxy is applied and the system is pumped to 1% vacuum, a computer controls the motor to move the bonding parts into contact. Since the entire operation is in vacuum, it leaves no trapped air and results in increased bonding strength. This apparatus confirmed the importance of surface preparation, including removal of air by starting the cure in vacuum (5 mm Hg) and subsequently releasing the vacuum [1].Another technique to improve the bonding strength utilizes the finding that a uniform epoxy resin layer between 50 µm and 150 µm [2] results in the optimal bonding strength. Here we applied spacers such as optic fiber (125 µm in diameter) or glass fiber fabric (150 µm in thickness) in between the bonding surfaces. These spacers ensure that the epoxy resin layer is of uniform thickness. It also utilizes the principle of glass-epoxy compositing to increase mechanical strength by fiber reinforcement and load distribution [3, 4].The above bonding apparatus has been proven to increase the bonding strength by experiments. Acoustic transducers bonded with this technique passed the high pressure, high temperature tests resembling the oil drilling conditions.