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Jonathan Lawrence - One of the best experts on this subject based on the ideXlab platform.

  • Correspondence
    2016
    Co-Authors: Jonathan Lawrence
    Abstract:

    2 A rapid, effective and repeatable technique for repairing the damaged skins of various military aircraft, both fixed and rotary winged, using high power diode laser (HPDL) radiation is described herein. The HPDL beam was traversed across the surface of an APC-2 repair patch, thereby melting a thermoplastic adhesive placed in between the repair patch and an Alclad substrate, consequently bonding the repair patch to the Alclad substrate. When subjected to single lap shear Tests, the shear strength of the bond generated with the HPDL radiation was 47.8 ± 4.7 MPa, compared to 32.4 ± 3.7 MPa for the induction welded samples. When subjected to the Boeing Wedge Test, the HPDL samples had a 1 hour crack growth rate that was rated as very good (1.9 ± 0.5 mm/h); for the induction welded samples the 1 hour crack growth rate that was rated as good (2.7 ± 1.2 mm/h). Of great significance was processing time achieved with the HPDL, which was reduced from 11.75 minutes when employing induction welding to 2.75 minutes with the HPDL. Moreover, the use of HPDL radiation has been shown in this work to be an effective means for bonding that is superior to its contemporary counterparts

  • A high power diode laser-based technique for the bonding of composite patches to aluminium alloys on various military aircraft
    Journal of Laser Applications, 2006
    Co-Authors: Jonathan Lawrence
    Abstract:

    A rapid, effective, and repeatable technique for repairing the damaged skins of various military aircraft, both fixed and rotary winged, using high power diode laser (HPDL) radiation is described herein. The HPDL beam was traversed across the surface of an APC-2 repair patch, thereby melting a thermoplastic adhesive placed inbetween the repair patch and an Alclad substrate, consequently bonding the repair patch to the Alclad substrate. When subjected to single lap shear Tests, the shear strength of the bond generated with the HPDL radiation was 47.8±4.7 MPa, compared to 32.4±3.7 MPa for the induction welded samples. When subjected to the Boeing Wedge Test, the HPDL samples had a 1 h crack growth rate that was rated as very good (1.9±0.5 mm/h); for the induction welded samples the 1 h crack growth rate that was rated as good (2.7±1.2 mm/h). Of great significance was processing time achieved with the HPDL, which was reduced from 11.75 min when employing induction welding to 2.75 min with the HPDL. Moreover,...

  • A high power diode laser (HPDL)-based technique for the bonding of composite patches to aluminium alloys on various military aircraft
    International Congress on Applications of Lasers & Electro-Optics, 2004
    Co-Authors: Jonathan Lawrence
    Abstract:

    A rapid, effective and repeatable technique for repairing the damaged skins of various military aircraft, both fixed and rotary winged, using a high power diode laser (HPDL) is described herein. The HPDL was traversed across the surface of an APC-2 repair patch, thereby melting a thermoplastic adhesive placed in between the repair patch and an Alclad substrate, consequently bonding the repair patch to the Alclad substrate. When subjected to single lap shear Tests, the shear strength of the HPDL bond was 47.8 ± 4.7 MPa, compared to 32.4 ± 3.7 MPa for the induction welded samples. When subjected to the Boeing Wedge Test, the HPDL samples had a 1 h crack growth rate that was rated as very good (1.9 ± 0.5 mm/h); for the induction welded samples the 1 h crack growth rate that was rated as good (2.7 ± 1.2 mm/h). Of great significance was processing time achieved with the HPDL, which was reduced from 11.75 mins when employing induction welding to 2.75 mins with the HPDL. Moreover, the HPDL has been shown in this work to be a tool for bonding that is superior to its contemporary counterparts. It is, therefore, distinctly possible that even stronger bonds could be achieved with the HPDL if different adhesives were used.A rapid, effective and repeatable technique for repairing the damaged skins of various military aircraft, both fixed and rotary winged, using a high power diode laser (HPDL) is described herein. The HPDL was traversed across the surface of an APC-2 repair patch, thereby melting a thermoplastic adhesive placed in between the repair patch and an Alclad substrate, consequently bonding the repair patch to the Alclad substrate. When subjected to single lap shear Tests, the shear strength of the HPDL bond was 47.8 ± 4.7 MPa, compared to 32.4 ± 3.7 MPa for the induction welded samples. When subjected to the Boeing Wedge Test, the HPDL samples had a 1 h crack growth rate that was rated as very good (1.9 ± 0.5 mm/h); for the induction welded samples the 1 h crack growth rate that was rated as good (2.7 ± 1.2 mm/h). Of great significance was processing time achieved with the HPDL, which was reduced from 11.75 mins when employing induction welding to 2.75 mins with the HPDL. Moreover, the HPDL has been shown in this...

Lawrence Jonathan - One of the best experts on this subject based on the ideXlab platform.

  • A high power diode laser (HPDL)-based technique for the bonding of composite patches to aluminium alloys on various military aircraft
    'Laser Institute of America', 2006
    Co-Authors: Lawrence Jonathan
    Abstract:

    A rapid, effective and repeatable technique for repairing the damaged skins of various military aircraft, both fixed and rotary winged, using high power diode laser (HPDL) radiation is described herein. The HPDL beam was traversed across the surface of an APC-2 repair patch, thereby melting a thermoplastic adhesive placed in between the repair patch and an Alclad substrate, consequently bonding the repair patch to the Alclad substrate. When subjected to single lap shear Tests, the shear strength of the bond generated with the HPDL radiation was 47.8 ± 4.7 MPa, compared to 32.4 ± 3.7 MPa for the induction welded samples. When subjected to the Boeing Wedge Test, the HPDL samples had a 1 hour crack growth rate that was rated as very good (1.9 ± 0.5 mm/h); for the induction welded samples the 1 hour crack growth rate that was rated as good (2.7 ± 1.2 mm/h). Of great significance was processing time achieved with the HPDL, which was reduced from 11.75 minutes when employing induction welding to 2.75 minutes with the HPDL. Moreover, the use of HPDL radiation has been shown in this work to be an effective means for bonding that is superior to its contemporary counterparts

Gary W. Critchlow - One of the best experts on this subject based on the ideXlab platform.

  • Use of carbon nanotubes reinforced epoxy as adhesives to join aluminum plates
    Materials & Design, 2010
    Co-Authors: Min Nah Tong, Gary W. Critchlow
    Abstract:

    Carbon nanotube (CNT)-reinforced epoxy was developed to use as adhesives. Mechanical stirring with ultrasonication was a simple and effective approach to obtain the adhesives with rather uniformly dispersed CNTs in the epoxy matrix. It was found that the thermal stability and electrical conductivity increased with the addition of CNT. The thermal degradation temperature of the adhesive with 1 wt.% of CNT was about 14 degrees C higher than that of neat epoxy. The percolation threshold for surface electrical conductivity was less than 0.5 wt.% of CNTs. In order to study the adhesion properties, two aluminum alloy plates were joined together with the adhesives with different amount of CNTs. The bonding strength and durability of the joints were studied in terms of Boeing Wedge Test under water of 60 degrees C, and both of them were found to increase significantly with the incorporation of CNTs. The specimen with neat epoxy was failed after immersion into water of 60 degrees C for 3 h, while as the specimen with 1 wt.% CNT-filled epoxy still showed fracture toughness as high as about 6.3 x 10(5) J/m(2) under the same Testing conditions. Nevertheless, the initial fracture toughness decreased with CNT fraction when CNT fraction was greater than 1 wt.%.

R. D. Adams - One of the best experts on this subject based on the ideXlab platform.

  • The Boeing Wedge Test revisited
    2000
    Co-Authors: R. D. Adams
    Abstract:

    The objective of this paper is to present a mechanics approach to the factors which lead to the successful or unsuccessful application of this apparently simple Test. Variables such as adherend thickness and yield strength, bondline thickness and the size of the introduced Wedge Test will be shown to have a significant influence on results, especially as adhesive and adherend characteristics are taken significantly away from the original concepts of Boeing.

Nigel. Porritt - One of the best experts on this subject based on the ideXlab platform.

  • The Durability of Adhesively Bonded Aluminium Alloy Joints: The Role of a Silane Pre-Treatment.
    2001
    Co-Authors: Nigel. Porritt
    Abstract:

    The use of adhesive bonding as a joining method has been the subject of interest to the aerospace industry over the last 50 years. It is now common place to use adhesive bonding in non-structural applications, however due to the increase in use of composite/metal and composite/composite aero-structures the identification and use of suitable adhesive bonding regimes has become a high priority. Currently one of the most important materials in the aircraft industry is aluminium and its alloys. To obtain strong durable joints some form of surface treatment of the aluminium is necessary. Pre-treatments that are commonly used today involve combinations of etching and anodising. In recent years there has been growing concern over the environmental impact of some of these treatments, particularly those that contain chromates. There is also the increasing pressure to undertake in-situ repair of aircraft structures using techniques not involving toxic, harmful materials or difficult anodising processes. To this end, there has been growing interest in the so-called "green", pre-treatments offered by silane adhesion promoters. The Boeing Wedge Test was used to identify the optimum durability characteristics for a number of silane process and solution variables. The experimental results indicated that optimum adhesive joint durability was obtained using a silane concentration of 1.0% in distilled water at an acid/alkali adjusted pH of 5.0 and hydrolysed for one hour at 23°C. This coating is then cured at 93°C for 1 hour. Work contained in this thesis has been able to identify the true fracture path associated with joint exposure to hot wet conditions. Joint failure with optimum silane conditions was identified as fracture through the silane inter-phase region, with some indication of microscopic stress assisted hydration of the oxide near the crack. The use of a pre-bonding hydration process in conjunction with the optimum silane pretreatment procedure has shown a marked improvement in the durability characteristics and, has in-fact, bettered the durability characteristics measured on the industry standard PAA and CAA pre-treated joints.