JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 55

hot platen press at 320ºC and 10 bar for 10 minutes. The samples to be welded were diamond-sawed from these laminates with dimensions 101.6 mm x 25.4 mm x 2 mm. The samples were degreased and dried at 135ºC for 6 hours in order to eliminate any moisture that could negatively influence the welding process [6]. After drying, the samples were kept in a desiccator until they were welded. In order to simplify the process, loose energy directors manufactured out of several layers of neat PEI resin were used for this study [7]. They were attached to the composite substrates with regular adhesive tape prior to welding. A microprocessor-controlled ACU Dynamic 3000 welding machine (Rinco Ultrasonic) was used to weld individual samples in a single-lap shear configuration (overlap length 12.7 mm). Apart from the basic parameters described in the introduction, this ultrasonic welding machine offers the possibility to increase the welding force at a certain build-up rate while the vibration is being applied. Likewise, the process can be directly controlled through the vibration time or indirectly, via either the welding energy or the distance travelled by the sonotrode. Based on previous experience, the travel of the sonotrode, expressed as a certain percentage of the total thickness of the energy director, was used as the controlling parameter. The rest of the processing parameters taken into account in this study were: the trigger force (at which the vibration was started), the build-up rate for the welding force, the amplitude of vibration, the solidification force (during the cooling-down stage) and the solidification time. The vibration frequency had a fixed value of 20 kHz. The outputs that could be obtained from the welding process were the melting time (i.e. the time it takes for the sonotrode to reach the specified travel), the maximum power (expressed as a percentage of the maximum available in the equipment, 3000 W) and the energy consumed. The quality of the welds was assessed by mechanical testing, cross section and fracture surface observations. Mechanical testing of the single-lap welds was performed in a Zwick 250 kN universal testing machine in compliance with the ASTM D1002 standard. The apparent lap shear strength (LSS) was calculated as the ultimate load divided by the overlap area. As a general procedure, five samples were tested per set of welding conditions. The DoE and the consequent

statistical analysis were carried out with the Minitab 15 program, under a 95% confidence interval, that is, the same α (false positive error, or probability of the outcome under the null hypothesis) value was used for all the calculations, α = 0.05 [5]. A two-level design was chosen, which means that two values of each factor, high and low configuration, were set. The full factorial design with two levels required 32 tests or runs to cover all the possible combinations of input settings, with the five factors mentioned before. Therefore, a fractional factorial design with 16 runs was chosen, which still offered an accurate analysis of the experiment [8]. No blocks were implemented, and the run order was randomized to reduce the possible effects depending on time or machine inertia [5]. To define the two levels for each variable within the designed experiment, processing thresholds were determined by fixing all the parameters at a reference value (travel 50%, trigger 600 N, build-up 0 N/s, solidification force 1000 N and solidification time 1200 ms), and varying one of them. Exceptionally, only one sample was tested per set of parameters. The high and low configurations were defined within those thresholds. The equipment offered nine possible levels for amplitude. The upper and lower levels, 86.2 and 51.8 µm, were considered as its imposed thresholds. The results from DoE were used to find optimum sets of welding conditions, which were then validated with the results from the initial analysis.

Fig. 1: Response tendencies for each parameter variation at a 86.2 µm amplitude

No70 January - February 2012 /

jec composites magazine 55



JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012

Cover
Edito
Point of view: Lanxess, the only fully integrated producer of glass reinforced thermoplastic
Contents
Agenda of Events
COMPANY & BUSINESS
- In Brief - Hexcel to commission two new carbon fibre production lines
- Core materials - Celebrating 25 years of ideas
- Fabrics - Diatex, a generation of growth
APPLICATIONS
- Motorbike - Brammo Empulse uses prepreg to drop weight
- Automotive - A revolution e-mobile concept car
- Automotive - Composite manufacturing simulation to drive process and design innovation
- Housing - A school made entirely of composites for 200 children
MARKET
- Wind - Double-digit growth for global wind O&M market
- China - «Companies with weak R&D capabilities will find it difficult to survive in the future»
- Certification - Rescoll qualified by Airbus for tests on composites
- Human ressources - CEO, designing strategy and corporate vision
FEATURE WIND ENERGY
- Resin - Polyurethane composites for wind turbine blades
- Prepreg - New best-in-class 10-kW wind turbine
- Trend - Composites in wind energy
- Design - Innovative design attempts for large-scale wind turbine blades
- Offshore - Vertiwind and Winflo, two projects for floating offshore wind turbines
RESEARCH & DEVELOPMENT
- Thermoplastics - Study of metal replacement with poly-etherimide/carbon fibre compounds in air-craft food tray arms
- Welding - Optimizing ultrasonic welding of carbon fibrereinforced polyetherimide
TECHNOLOGY & INNOVATIONS
- Innovation
- NDT - Health monitoring assessment and non-destructive inspection of composite structures for surface transport applications
- Manufacturing - Composites are the materials for the future
Index
In the world
Asia: 4 conferences
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - Cover
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 2
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - Edito
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - Point of view: Lanxess, the only fully integrated producer of glass reinforced thermoplastic
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 5
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - Contents
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 7
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - Agenda of Events
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - Ad1
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - Ad2
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - In Brief - Hexcel to commission two new carbon fibre production lines
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - Core materials - Celebrating 25 years of ideas
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 11
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - Fabrics - Diatex, a generation of growth
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - Motorbike - Brammo Empulse uses prepreg to drop weight
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - Automotive - A revolution e-mobile concept car
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 15
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - Automotive - Composite manufacturing simulation to drive process and design innovation
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - Housing - A school made entirely of composites for 200 children
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 18
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - Wind - Double-digit growth for global wind O&M market
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 20
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - China - «Companies with weak R&D capabilities will find it difficult to survive in the future»
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 22
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 23
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - Certification - Rescoll qualified by Airbus for tests on composites
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - Human ressources - CEO, designing strategy and corporate vision
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 26
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 27
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 28
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - Resin - Polyurethane composites for wind turbine blades
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 30
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 31
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 32
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 33
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 34
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - Prepreg - New best-in-class 10-kW wind turbine
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - Trend - Composites in wind energy
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 37
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 38
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - Design - Innovative design attempts for large-scale wind turbine blades
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 40
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 41
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 42
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 43
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 44
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 45
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - Offshore - Vertiwind and Winflo, two projects for floating offshore wind turbines
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 47
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - Thermoplastics - Study of metal replacement with poly-etherimide/carbon fibre compounds in air-craft food tray arms
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 49
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 50
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 51
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 52
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 53
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - Welding - Optimizing ultrasonic welding of carbon fibrereinforced polyetherimide
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 55
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 56
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 57
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 58
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - Innovation
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - NDT - Health monitoring assessment and non-destructive inspection of composite structures for surface transport applications
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 61
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 62
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 63
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - - Manufacturing - Composites are the materials for the future
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - Index
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - In the world
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - Asia: 4 conferences
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 68
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 69
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 70
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 71
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 72
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 73
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 74
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 75
JEC COMPOSITES MAGAZINE - Issue #70 - January/February 2012 - 76
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