The Experts below are selected from a list of 354 Experts worldwide ranked by ideXlab platform

Cristina Gonzalez - One of the best experts on this subject based on the ideXlab platform.

  • considerations for the industrial application of structural adhesive joints in the aluminium composite material bonding
    Composites Part B-engineering, 2013
    Co-Authors: Jose M Arenas, Cristina Alia, Julian J Narbon, R Ocana, Cristina Gonzalez
    Abstract:

    Abstract The composite materials of the polymeric matrix reinforced with carbon fibre have an extensive industrial application as they provide light and resistant structures. However, in many products (automobiles, aircraft, etc.) the structural adhesive parts must be joined to other components manufactured with aluminium alloys. The use of structural adhesive to carry out these bonds may be a good alternative if a specific design of the adhesive joint is carried out maximising its performance and reducing its limitations. In this respect, one of the most relevant aspects of the design of the joint consists of the selection of the structural adhesive and the most appropriate surface treatment for the substratum. The present paper describes a procedure to optimise this decision by means of the combination of experimental techniques with multi-criteria decision tools. This methodology allows selecting, amongst the various alternatives, the adhesive and surface treatment better combining mechanical performance and adaptation to the manufacturing process. Thus, it has been concluded that polyurethane adhesive with a Peel Ply surface treatment for carbon fibre, and sandpapered for aluminium, are the best alternatives.

  • Considerations for the industrial application of structural adhesive joints in the aluminium–composite material bonding
    Composites Part B-engineering, 2012
    Co-Authors: Jose M Arenas, Cristina Alia, Julian J Narbon, R Ocana, Cristina Gonzalez
    Abstract:

    Abstract The composite materials of the polymeric matrix reinforced with carbon fibre have an extensive industrial application as they provide light and resistant structures. However, in many products (automobiles, aircraft, etc.) the structural adhesive parts must be joined to other components manufactured with aluminium alloys. The use of structural adhesive to carry out these bonds may be a good alternative if a specific design of the adhesive joint is carried out maximising its performance and reducing its limitations. In this respect, one of the most relevant aspects of the design of the joint consists of the selection of the structural adhesive and the most appropriate surface treatment for the substratum. The present paper describes a procedure to optimise this decision by means of the combination of experimental techniques with multi-criteria decision tools. This methodology allows selecting, amongst the various alternatives, the adhesive and surface treatment better combining mechanical performance and adaptation to the manufacturing process. Thus, it has been concluded that polyurethane adhesive with a Peel Ply surface treatment for carbon fibre, and sandpapered for aluminium, are the best alternatives.

John W Connell - One of the best experts on this subject based on the ideXlab platform.

  • laser ablation surface preparation for adhesive bonding of carbon fiber reinforced epoxy composites
    International Journal of Adhesion and Adhesives, 2016
    Co-Authors: Frank Palmieri, Marcus A Belcher, Christopher J Wohl, Kay Youngdahl Blohowiak, John W Connell
    Abstract:

    Abstract Adhesive bonding of carbon fiber reinforced plastic (CFRP) epoxy composites provides many advantages over mechanical fastening for assembling aerospace structures including weight savings, reduced manufacturing flow, and added structural efficiency. To ensure the reliability of bonded joints in primary airframe structures, the surface preparation method and execution are critical. Surface preparation is widely recognized as a key step in the bonding process and is one element of a bonding method that must be controlled to produce robust and predictable bonds in a precise and repeatable manner. Laser ablation of composite surface resin can provide an efficient, precise, and reproducible means of preparing composite surfaces for adhesive bonding. Advantages include elimination of physical waste (i.e., grit media and sacrificial Peel Ply layers that ultimately require disposal), reduction in process variability due to increased precision (e.g. monitoring laser parameters), and automation of surface preparation. This paper describes a surface preparation technique using a nanosecond, frequency-tripled Nd:YAG laser source. Lap shear specimens were laser treated and tested and apparent shear strength and failure modes of lap shear specimens were used to assess mechanical performance over a three-year accelerated aging study by exposing bonded specimens to 71 °C (160 °F) and 85% relative humidity.

  • Supersonic Retropulsion Surface Preparation of Carbon Fiber Reinforced Epoxy Composites for Adhesive Bonding
    2013
    Co-Authors: Frank L. Palmieri, Marcus A Belcher, Christopher J Wohl, Kay Youngdahl Blohowiak, John W Connell
    Abstract:

    Surface preparation is widely recognized as a key step to producing robust and predictable bonds in a precise and reproducible manner. Standard surface preparation techniques, including grit blasting, manual abrasion, and Peel Ply, can lack precision and reproducibility, which can lead to variation in surface properties and subsequent bonding performance. The use of a laser to ablate composite surface resin can provide an efficient, precise, and reproducible means of preparing composite surfaces for adhesive bonding. Advantages include elimination of physical waste (i.e., grit media and sacrificial Peel Ply layers that ultimately require disposal), reduction in process variability due to increased precision (e.g. increased reproducibility), and automation of surface preparation, all of which improve reliability and process control. This paper describes a Nd:YAG laser surface preparation technique for composite substrates and the mechanical performance and failure modes of bonded laminates thus prepared. Additionally, bonded specimens were aged in a hot, wet environment for approximately one year and subsequently mechanically tested. The results of a one year hygrothermal aging study will be presented.

  • Laser surface preparation for bonding of aerospace composites
    Proceedings of the Institution of Civil Engineers - Engineering and Computational Mechanics, 2011
    Co-Authors: Marcus A Belcher, Christopher J Wohl, John W. Hopkins, John W Connell
    Abstract:

    Adhesive bonds are critical to the integrity of built-up structures. Disbonds can often be detected but the strength of adhesion between surfaces in contact cannot be determined without destructive testing. Typically the major problem in a bonded structure is surface contamination, and by extension, surface preparation. Standard surface preparation techniques, including grit blasting, manual abrasion, and Peel Ply, are not ideal because of variations in their application. Etching of carbon-fibre-reinforced plastic (CFRP) panels using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser appears to be a highly precise, controlled, and reliable way to both clean a composite surface prior to bonding and provide a bond-promoting patterned surface akin to Peel Ply without the inherent drawbacks from the same (i.e. debris and curvature). CFRP surfaces prepared using laser patterns conducive to adhesive bonding were compared with typical pre-bonding surface treatments through optical microscopy, contact angle...

  • Laser Surface Preparation for Adhesive Bonding of Aerospace Structural Composites
    2010
    Co-Authors: Marcus A Belcher, Christopher J Wohl, John W. Hopkins, John W Connell
    Abstract:

    Adhesive bonds are critical to the integrity of built-up structures. Disbonds can often be detected but the strength of adhesion between surfaces in contact is not obtainable without destructive testing. Typically the number one problem in a bonded structure is surface contamination, and by extension, surface preparation. Standard surface preparation techniques, including grit blasting, manual abrasion, and Peel Ply, are not ideal because of variations in their application. Etching of carbon fiber reinforced plastic (CFRP) panels using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser appears to be a highly precise and promising way to both clean a composite surface prior to bonding and provide a bond-promoting patterned surface akin to Peel Ply without the inherent drawbacks from the same (i.e., debris and curvature). CFRP surfaces prepared using laser patterns conducive to adhesive bonding were compared to typical pre-bonding surface treatments through optical microscopy, contact angle goniometry, and post-bonding mechanical testing.

  • Environmental Aging of Scotch-Weld(TradeMark) AF-555M Structural Adhesive in Composite to Composite Bonds
    2010
    Co-Authors: Tan-hung Hou, John W Connell, Gilda A. Miner, Sharon E. Lowther, James M. Baughman
    Abstract:

    Fiber reinforced resin matrix composites have found increased usage in recent years. Due to the lack of service history of these relatively new material systems, their long-term aging performance is not well established. In this study, adhesive bonds were prepared by the secondary bonding of Scotch-Weld(TradeMark) AF-555M between pre-cured adherends comprised of T800H/3900-2 uni-directional laminate. The adherends were co-cured with wet Peel-Ply for surface preparation. Each bond-line of single-lap-shear (SLS) specimen was measured to determine thickness and inspected visually for voids. A three-year environmental aging plan for the SLS specimens at 82 C and 85% relative humidity was initiated. SLS strengths were measured for both controls and aged specimens at room temperature and 82 C. The aging results of strength retention and failure modes to date are reported.

Clemens Schmidt-eisenlohr - One of the best experts on this subject based on the ideXlab platform.

  • OPTIMIZED VACUUM BAGGING FOR CFRP ROCKETBOOSTER CASES
    2018
    Co-Authors: Jan Faber, Clemens Schmidt-eisenlohr
    Abstract:

    State of the art vacuum bagging for vacuum infusion technologies still involves a high amount of manual process steps. More efficient production technologies could increase the economic attractiveness of vacuum infusion processes for large aerospace structures. In the context of a research project, the German Aerospace Center (DLR), Augsburg and MT Aerospace GmbH, Augsburg have developed design methods and application concepts for vacuum bagging auxiliary materials on a full-scale CFRP rocket booster case. With a diameter of 3.4 m manual application of auxiliary materials is challenging in terms of deposition accuracy, reproducibility and reachability. Facing these challenges, first, a design method has been developed to generate near net-shape auxiliary material packages of Peel Ply, perforated release film and flow media with reduced wrinkling. As joining technology continuous ultrasonic welding has been selected and validated based on the suitability for vacuum infusion and out-of-autoclave curing. Manual application tests were conducted with these packages on a full-scale booster case demonstrator. The results show, that a developable shape design of the packages for the doubly curved dome sections allows best results with regards to wrinkle minimization and the complexity of the handling procedure. Second, a concept study on the application of the outer vacuum bag, consisting of membrane and vacuum foil, is presented. Therefore, an optimized shape design of a VAP membrane combined with a new application concept has been developed and validated. In a final outlook, the results will be discussed focusing on intended low manufacturing rates of about 20 boosters per year.

  • Introduction of a Multi Kinematic Gripping System for the Vacuum Bagging Process of Complex Shaped Aerospace Composite Structures
    2017
    Co-Authors: Clemens Schmidt-eisenlohr, Michael Vistein, Lars Brandt
    Abstract:

    In batch production of large aerospace CFRP structures, vacuum bagging is typically performed manually. The quality of the vacuum bagging is essential to produce high quality composite parts. Since the development of automation technologies is not costefficient if applied only to the vacuum bagging process, major investments are currently avoided. The increased build up of automation solutions in other areas of composite production provides a base for automating the vacuum bagging and thus impacting the part quality positively. The complexity of the vacuum bagging for large integral structures is caused by the multiplicity of cut piece shapes and used auxiliary materials. Additionally, these various cut pieces need to be deposited precisely on doubled-curved surfaces. For these reasons, an automation system needs to be adaptive for a wide range of geometric constraints. To face these challenges, a first automation concept—based on a multi kinematic gripping system—is developed and investigated at the Center for Lightweight Production Technology (ZLP) of the German Aerospace Center (DLR). The gripping system is designed with three kinematically independent manipulators attached to a 6-DOF industrial robot, thus providing three geometrically independent gripping elements within a large working space. First experimental investigations are carried out on a full scale demonstrator to achieve basic knowledge on the use of the multi kinematic system and its handling interaction with auxiliary materials. It is shown that a pick and place process is possible for different shapes of cut pieces, different materials (Peel Ply, release film, membrane) and various tooling curvatures. A high potential for a reasonable application in an automated vacuum bagging process is presented.

  • AUTOMATED HANDLING OF AUXILIARY MATERIALS FOR VACUUM BAGGING IN CFRP FUSELAGE PRODUCTION
    2016
    Co-Authors: Jan Faber, Clemens Schmidt-eisenlohr
    Abstract:

    In order to match a predicted production ramp-up in aircraft production, state of the art manufacturing techniques have to be optimized regarding productivity and efficiency. Especially vacuum infusion techniques for large CFRP structures still involve a high amount of manual work. In detail, the vacuum bagging depends on manual lay-up processes of auxiliary materials. A first approach of automation concepts for robot-based vacuum bagging will be discussed in this paper. In a research project at the Center for Leigtweight Production Technology in Augsburg, automated manufacturing of a single-curved CFRP fuselage demonstrator has been investigated. A rigid gripping system with needle grippers has been developed and validated for the application of auxiliary materials as Peel Ply, release film and airweave on the top of a dry fiber preform. Alongside the process chain, handling and positioning procedures have been analyzed both analytically and in experimental test series. According to the rigidity of the gripping system, an adequate motion concept for the fuselage demonstrator has been found. The gripping system allows pick-up, transportation and positioning of auxiliary material packages on a single-curved preform with high accuracy. Based on these results conclusions for future vacuum bagging processes can be drawn.

  • AUTOMATED HANDLING OF AUXILIARY MATERIALS FOR VACUUM BAGGING IN CFRP FUSELAGE PRODUCTION
    2016
    Co-Authors: Jan Faber, Clemens Schmidt-eisenlohr
    Abstract:

    In order to match a predicted production ramp-up in aircraft production, state of the art manufacturing techniques have to be optimized regarding productivity and efficiency. Especially vacuum infusion techniques for large CFRP structures still involve a high amount of manual work. In detail, the vacuum bagging depends on manual lay-up processes of auxiliary materials. A first approach of automation concepts for robot-based vacuum bagging will be discussed in this paper. In a research project at the Center for Leigtweight Production Technology in Augsburg, automated manufacturing of a single-curved CFRP fuselage demonstrator has been investigated. A rigid gripping system with needle grippers has been developed and validated for the application of auxiliary materials as Peel Ply, release film and airweave on the top of a dry fiber preform. Alongside the process chain, handling and positioning procedures have been analyzed both analytically and in experimental test series. According to the rigidity of the gripping system, an adequate motion concept for the fuselage demonstrator has been found. The gripping system allows pick-up, transportation and positioning of auxiliary material packages on a single-curved preform with high accuracy. Based on these results conclusions for future vacuum bagging processes can be drawn.

Martin Wiedemann - One of the best experts on this subject based on the ideXlab platform.

  • Characterisation of the sliding friction response of Peel-Ply textured surfaces
    Composites Part A-applied Science and Manufacturing, 2014
    Co-Authors: Lennart Weiß, Thilo Glaser, Christian Hühne, Martin Wiedemann
    Abstract:

    The present paper reports on effects of texture, contamination by aircraft operating fluids, and contact pressure on the sliding friction response of polymer surfaces. This study provides essential data necessary for the design of friction-based energy absorption devices. Their functionality is ought to integrate into structural elements of aircraft fuselages made from carbon fibre reinforced plastics. The paper specifically addresses epoxy resin surfaces of continuous fibre reinforced composite material currently applied in aircraft industry. Peel-Ply was utilised to achieve the characteristic surface texture. A pin-on-flat type test apparatus was designed and used to determine the friction coefficient as a function of the initial surface texture, the contamination by five different aircraft operating fluids, as well as the contact pressure. The sliding friction results obtained in this study indicate a significant influence of both, the surface texture and the state of contamination.

  • Characterisation of the sliding friction response of Peel-Ply textured surfaces Part A Applied science and manufacturing
    Composites, 2014
    Co-Authors: Lennart Weiß, Thilo Glaser, Christian Hühne, Martin Wiedemann
    Abstract:

    The present paper reports on effects of texture, contamination by aircraft operating fluids, and contact pressure on the sliding friction response of polymer surfaces. This study provides essential data necessary for the design of friction-based energy absorption devices. Their functionality is ought to integrate into structural elements of aircraft fuselages made from carbon fibre reinforced plastics. The paper specifically addresses epoxy resin surfaces of continuous fibre reinforced composite material currently applied in aircraft industry. Peel-Ply was utilised to achieve the characteristic surface texture. A pin-on-flat type test apparatus was designed and used to determine the friction coefficient as a function of the initial surface texture, the contamination by five different aircraft operating fluids, as well as the contact pressure. The sliding friction results obtained in this study indicate a significant influence of both, the surface texture and the state of contamination.

Jose M Arenas - One of the best experts on this subject based on the ideXlab platform.

  • considerations for the industrial application of structural adhesive joints in the aluminium composite material bonding
    Composites Part B-engineering, 2013
    Co-Authors: Jose M Arenas, Cristina Alia, Julian J Narbon, R Ocana, Cristina Gonzalez
    Abstract:

    Abstract The composite materials of the polymeric matrix reinforced with carbon fibre have an extensive industrial application as they provide light and resistant structures. However, in many products (automobiles, aircraft, etc.) the structural adhesive parts must be joined to other components manufactured with aluminium alloys. The use of structural adhesive to carry out these bonds may be a good alternative if a specific design of the adhesive joint is carried out maximising its performance and reducing its limitations. In this respect, one of the most relevant aspects of the design of the joint consists of the selection of the structural adhesive and the most appropriate surface treatment for the substratum. The present paper describes a procedure to optimise this decision by means of the combination of experimental techniques with multi-criteria decision tools. This methodology allows selecting, amongst the various alternatives, the adhesive and surface treatment better combining mechanical performance and adaptation to the manufacturing process. Thus, it has been concluded that polyurethane adhesive with a Peel Ply surface treatment for carbon fibre, and sandpapered for aluminium, are the best alternatives.

  • Considerations for the industrial application of structural adhesive joints in the aluminium–composite material bonding
    Composites Part B-engineering, 2012
    Co-Authors: Jose M Arenas, Cristina Alia, Julian J Narbon, R Ocana, Cristina Gonzalez
    Abstract:

    Abstract The composite materials of the polymeric matrix reinforced with carbon fibre have an extensive industrial application as they provide light and resistant structures. However, in many products (automobiles, aircraft, etc.) the structural adhesive parts must be joined to other components manufactured with aluminium alloys. The use of structural adhesive to carry out these bonds may be a good alternative if a specific design of the adhesive joint is carried out maximising its performance and reducing its limitations. In this respect, one of the most relevant aspects of the design of the joint consists of the selection of the structural adhesive and the most appropriate surface treatment for the substratum. The present paper describes a procedure to optimise this decision by means of the combination of experimental techniques with multi-criteria decision tools. This methodology allows selecting, amongst the various alternatives, the adhesive and surface treatment better combining mechanical performance and adaptation to the manufacturing process. Thus, it has been concluded that polyurethane adhesive with a Peel Ply surface treatment for carbon fibre, and sandpapered for aluminium, are the best alternatives.