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- Englisch (10) (entfernen)
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- Bonding strength (3)
- Adhesive strength (2)
- Air-coupled ultrasound (2)
- Centrifuge technology (2)
- Ferroelectret (2)
- High pressure airborne ultrasound (2)
- Multi-sample approach (2)
- Thermo-acoustic (2)
- Transducer (2)
- Adhesion (1)
Organisationseinheit der BAM
A novel approach for the generation of broadband airborne ultrasound by using the thermo-acoustic effect is presented in this contribution. We investigate the applicability of resonance-free thermo-acoustic emitters for generation of very short high pressure airborne ultrasound pulses. A thermoacoustic emitter consisting of a 30 nm thin metallic film on a usual soda-lime glass substrate generates sound pressure values of more than 140 dB at 60 mm distance. The results are compared with conventional piezoelectric airborne ultrasound transducers. Our investigations show the applicability of the thermo-acoustic devices for broadband and high pressure ultrasound emitters using pulse excitation.
Ferroelectrets are promising materials for air-coupled ultrasonic transducers. A transducer made of polarized cellular polypropylene, including its electronic interface, was developed and compared with conventional air-coupled probes. Test pieces of fiber-reinforced polymer containing impact flaws and flat-bottom holes were inspected in transmission. The ferroelectret transducers achieved a considerably higher signal-to-noise ratio. The impacts were clearly visible with all transducers, but less noisy with ferroelectret transducers. The flat-bottom holes were better detectable than with a conventional probe with about the same focus size.
In this contribution we present a novel thermo-acoustic approach for the generation of broad band airborne ultrasound and investigate the applicability of resonance-free thermo-acoustic emitters for very short high pressure airborne ultrasound pulses. We report on measurements of thermo-acoustic emitter consisting of a 30 nm thin metallic film on a usual soda-lime glass substrate, generating sound pressure values of more than 140 dB at 60 mm distance from the transducer and compare the results with conventional piezoelectric airborne ultrasound transducers. Our experimental investigations show that such thermo-acoustic devices can be used as broad band emitters using pulse excitation.
Air-coupled ferroelectret ultrasonic transducers applied to testing of fiber-reinforced polymers
(2013)
Multiple-sample approach: reliable ranking and validated statistics of bonding and adhesive strength
(2014)
Bonding strength of adhesive-bonded joints and adhesive strength of coatings have been exclusively determined in
single-sample tests using a tensile testing machine. Necessarily, the single-sample approach was also applied to the
corresponding bonding procedure. As a consequence, reliability and reproducibility of results were restricted. By
applying the newly introduced centrifuge technology, the multiple-sample approach was realized for simultaneous
tensile testing of up to eight samples under identical conditions without any disturbing shear-force effects. In order to
introduce the multiple-sample approach into the bonding procedure, a hydraulic bonding set-up was developed which
enables identical bonding pressure also for slightly different heights of sample assemblies. Both sample approaches
were compared for various application examples: ranking of different classes of adhesives, validated statistics of
adhesive-bonded joints using one particular adhesive and effects of cleaning and plasma-treatment on the adhesive
strength of coatings. The investigated systems included glass, metals and polymer substrates, different adhesives,
metallic and dielectric coatings on polymers.
Multiple-sample approach: reliable ranking and validated statistics of bonding and adhesive strength
(2014)
Bonding strength of adhesive-bonded joints and adhesive strength of coatings have been exclusively determined in single-sample tests using a tensile testing machine. Necessarily, the single-sample approach was also applied to the corresponding bonding procedure. As a consequence, reliability and reproducibility of results were restricted. By applying the newly introduced centrifuge technology, the multiple-sample approach was realized for simultaneous tensile testing of up to eight samples under identical conditions without any disturbing shear-force effects. In order to introduce the multiple-sample approach into the bonding procedure, a hydraulic bonding set-up was developed which enables identical bonding pressure also for slightly different heights of sample assemblies. Both sample approaches were compared for various application examples: ranking of different classes of adhesives, validated statistics of adhesive-bonded joints using one particular adhesive and effects of cleaning and plasma-treatment on the adhesive strength of coatings. The investigated systems included glass, metals and polymer substrates, different adhesives, metallic and dielectric coatings on polymers.
The multiple-sample approach by means of centrifugal adhesion testing (CAT-technology) allows the determination of bonding strength of adhesive-bonded joints on a statistical basis of up to eight samples. Therefore, it is obvious to ensure the continuous handling and identical processing of an octet of samples within the entire process chain of wet-chemical cleaning, plasma-chemical pre-treatment, bonding of samples, and testing of bonding strength. Within the multiple-sample bonding set-up (MPKV-technology) a defined bonding pressure can be adjusted regardless the actual number of samples. A comparison of single- and multiple-sample approach is made for bonding strength of selected adhesives, double-sided adhesive tapes and different material combinations [stainless steel (V2A) vs. stainless steel, polyamide (PA), or polypropylene (PP)]. It is shown that both technologies improve reliability of results
The future commercial prospects for adhesive tapes are very good and its application range is very broad. From every-day-use in office, packaging, maintenance, and quick repair in workshops, it ranges from handicraft work, medical purposes and cosmetics up to workmanship. The study describes a new multi-sample approach in adhesive tape testing from theoretical background, preparation of test specimen for tensile as well as shear testing, detailed measurement procedures up to analysis and result interpretation. Various types of single and double-sided pressure sensitive adhesive tapes supplied by different manufacturers were investigated and compared
Phage display biopanning with Illumina next-generation sequencing (NGS) is applied to reveal insights into peptide-based adhesion domains for polypropylene (PP). One biopanning round followed by NGS selects robust PP-binding peptides that are not evident by Sanger sequencing. NGS provides a significant statistical base that enables motif analysis, statistics on positional residue depletion/enrichment, and data analysis to suppress false-positive sequences from amplification bias. The selected sequences are employed as water-based primers for PP-metal adhesion to condition PP surfaces and increase adhesive strength by 100% relative to nonprimed PP.