Physical and Mechanical Properties of Natural Fiber Polyester Laminate Composites

The utilization of natural fibers as reinforcing composites has been widely used. Indonesia has natural fibers abundantly such as ijuk fiber (Arenga pinnata), sisal fiber (Agave Sisalana) and coconut fiber (Cocos Nucifera). Random orientation application of the fiber in composites affected to the lower properties. Therefore, the particular orientation of fibres wereapplied in manufacturing of composite by laminating the short fiber with Polyurethane (PU) adhesive. The size and moisture content (MC) of fiber were 14-15 cm and +10%, respectively. The resin content of PU was 5% by weight of the laminate sheet. The mixture of fibers and PU adhesive was cold pressed for 5 minutes with a thickness of 0.5-1 mm. The laminate sheet of PU-adhesive fibers then mixed with unsaturated polyester resin layer by layer. The fiber laminate composition of composite was varieted such as 1, 2 and 3 layers. The hand layup method was used in the manufacturing of the composite. The physical and mechanical testing like density, moisture content, water absorption, thickness swelling, flexural test (adapt to ASTM D 790 standard) and tensile test (adapt to ASTM D 638 standard) were carried out. In additionmorphological analyses were investigated on composite samples. The results research showed that the net density of polyester, ijuk fiber sheet, sisal fiber sheet, and coconut fiber sheet were 1.21, 0.9, 0.53 and 0.22 g/cm3. The range of composite density was 0.99-1.15 g/cm3. The single layer composite had lower thickness swelling and water absorption than those of the three layers composite. The highest tensile strength of three layers of sisal fiber composite was higher (33.84 MPa) than that of the three layers of coconut fiber composite (12.04 MPa). The flexural strength of double layers composite from fiber sisal was higher (63.16 MPa) than that of three layers coconut fiber composite (28.65 MPa).

C-Anchor for Strengthening the Connection between Adhesively Bonded Laminates and Concrete Substrates

A new carbon fiber reinforced polymer (CFRP) anchor is developed and tested to delay debonding in reinforced concrete (RC) beams externally strengthened with FRP laminate/sheet. The C-shape anchor is made from a commercially available CFRP grid. The anchors legs are 95 mm long while the spacing between the legs is adjustable, depending on FRP laminate and beam widths. Nine full scale RC beams, 3.0 m long, 250 mm wide and 400 mm deep, were strengthened with CFRP laminate/sheet, with and without the C-anchor. The main test parameters were the type and amount of FRP laminate and the presence/absence of the anchor. Test results showed that beams with the anchor had generally 5%–10% higher debonding and failure load, and they reached higher deflection at failure than the companion beams without anchors. Although complete separation of the FRP laminate from the concrete was not observed in any of the beams with anchors, there was noticeable slip at failure at one end of the laminate. A significant outcome of the study is that anchors are effective in limiting the extent of debonding along the laminate, thus contributing to the flexural stiffness of the beam by reducing the extent of cracking and limiting the crack width along the beam. Finally, the anchor allowed the FRP to reach or exceed its theoretically allowable strain computed based on the American Concrete Institute (ACI) Committee 440 recommendation while in none of the beams without anchors, the FRP reached its theoretically allowable strain.

C-Anchor for Strengthening the Connection between Adhesively Bonded Laminates and Concrete Substrates

A new carbon fiber reinforced polymer (CFRP) anchor is developed and tested to delay debonding in reinforced concrete (RC) beams externally strengthened with FRP laminate/sheet. The C-shape anchor is made from a commercially available CFRP grid. The anchors legs are 95 mm long while the spacing between the legs is adjustable, depending on FRP laminate and beam widths. Nine full scale RC beams, 3.0 m long, 250 mm wide and 400 mm deep, were strengthened with CFRP laminate/sheet, with and without the C-anchor. The main test parameters were the type and amount of FRP laminate and the presence/absence of the anchor. Test results showed that beams with the anchor had generally 5%–10% higher debonding and failure load, and they reached higher deflection at failure than the companion beams without anchors. Although complete separation of the FRP laminate from the concrete was not observed in any of the beams with anchors, there was noticeable slip at failure at one end of the laminate. A significant outcome of the study is that anchors are effective in limiting the extent of debonding along the laminate, thus contributing to the flexural stiffness of the beam by reducing the extent of cracking and limiting the crack width along the beam. Finally, the anchor allowed the FRP to reach or exceed its theoretically allowable strain computed based on the American Concrete Institute (ACI) Committee 440 recommendation while in none of the beams without anchors, the FRP reached its theoretically allowable strain.

Magnetically levitated X–Y plane actuator for micromanufacturing

The paper presents design and development of a precision motion actuator, which can traverse required trajectory in the X–Y plane and can be used for micromachining applications using magnetic levitation based technology. A glass-reinforced epoxy laminate sheet with micromachined holes in the horizontal and vertical direction with copper wires placed vertically and horizontally was used for actuation of rare earth magnets wherein a pyrolytic graphite sheet was fixed over the copper wires. The diamagnetism of pyrolytic graphite sheet coupled with electromagnetic field generated because of the current passing through the copper wires led to levitation and actuation of the rare earth magnet over desired trajectory. COMSOL Multiphysics (COMSOL Inc., Burlington, Massachusetts, USA) simulation was conducted in order to simulate the forces generated by the developed actuator. Thereafter, the forces generated by the actuator with current flowing through the wires were measured using a dynamometer where the error was limited within 2%. An acrylic sheet was fixed over the actuator and laser micromachining was conducted with trajectories traversed by the actuator. Scanning electron microscope results of the machined samples confirmed that feature sizes in the range of 200–300 micron could be generated. This proves the potential of the developed actuator for micromachining applications.

Study on Tensile Fractured Surfaces and Toughening Mechanism of Ti/Ti-Al Micro-Laminate Sheet

Large-sized Ti/Ti-Al micro laminated thin sheet with thickness of 0.12mm was prepared by high-power electron beam physical vapor deposition technology, and then tensile tests of specimen after hot-pressing densification were carried out at room and high temperature, and tensile specimen was examined the fractured surfaces by SEM and OM. It was found that the tensile specimen under room temperature presents a compound quasi-cleavage and intergranular fracture, and a certain plastic deformation of Ti toughening layer was detected during fracture process. Tensile fractured surfaces under high temperature present the feature of compound dimple models and quasi-cleavage, furthermore, the size and the quantity of dimple exhibited an enhancing trend with test temperature increased. Results show that the cracks will stagger along the inter-laminar interface or the layer due to which micro-laminate expresses a good characteristic of delayed fracture. The toughening mechanisms are that the crack deflection and micro-bridge connection caused by the toughening layers increases crack propagation resistance.