Search results for " Toughness"
showing 10 items of 83 documents
Electrospun rubber/thermoplastic hybrid nanofibers for localized toughening effects in epoxy resins
2020
Synthetic rubber/thermoplastic blends were electrospun from their solutions. The rubber was a solid acrylonitrile/butadiene/acrylic acid copolymer and the thermoplastic was polyacrylonitrile. The aims of this study were to identify suitable systems and processing conditions for obtaining rubber-based electrospun nanofibers, to investigate the ability of an epoxy resin system to impregnate and swell selected hybrid rubber/thermoplastic mats, and to assess the impact of the nanofibers on the resin morphology and curing behavior. In particular, electrospinning trials were carried out varying the composition of the feed solution and process parameters, such as the applied voltage, the flow rate…
Mode I interlaminar fracture toughness of thin-ply laminates with CNT webs at the crack interface
2019
Abstract Pristine and functionalized carbon nanotube (CNT) webs were introduced at the interlaminar region of two different thin-ply carbon fibre reinforced polymer systems (NTPT 402 prepreg, and TeXtreme/SE84LV). The Mode I interlaminar fracture toughness (ILFT) for the NTPT 402 material was substantially lower. In contrast when SE84LV resin was used, the resistance curves were virtually unchanged and with no depreciation in the steady state value of the ILFT. This demonstrates that a careful choice of the resin is essential to permit the embedding of CNT webs in thin-ply laminates without compromising structural performance and opens a new way towards the development of multifunctional th…
Accelerated ageing due to moisture absorption of thermally cured epoxy resin/polyethersulphone blends. Thermal, mechanical and morphological behaviour
2011
Abstract A model epoxy resin/anhydride system, modified with a polyethersulfone (PES) engineering thermoplastic toughening agent, has been studied under hydrothermal ageing in order to investigate the modification of the thermal, morphological and mechanical behaviour through dynamical mechanical thermal analysis, SEM microscopy and fracture toughness test respectively. Two different concentrations of the toughening agent were used in the blends and two ageing conditions have been considered, consisting of the immersion of the samples in distilled water at constant temperature of 70 °C for 1 week and for 1 month. Dynamical mechanical thermal analysis results on hydrothermally aged materials…
Mode I fracture toughness behavior of hydro-thermally aged carbon fibre reinforced DGEBA-HHPA-PES systems
2012
In this work the Mode I fracture toughness behavior of unidirectional CFRP laminates is investigated by means of Double Cantilever Beam (DCB) tests. The composite samples were manufactured by thermal curing after impregnation of a Carbon fabric with a DGEBA epoxy and anhydride HHPA curing agent. One resin batch was also mixed with a PES thermoplastic monomer to enhance the matrix toughness. Two lots of samples, toughened and un-toughened, were then left to soak in hot water to achieve various degrees of aging. The influence of matrix toughening and hydrothermal aging on the delamination behavior of the composite have then been assessed and correlated with characterization data from Dynamic …
Review of photoelastic image analysis applied to structural birefringent materials: glass and polymers
2015
Photoelasticity is particularly suitable for the analysis of the stress state in structural materials that are transparent and birefringent. Some techniques of digital photoelasticity (phase shifting and RGB) are applied to the analysis of stress field in two classes of structural materials. The first one consists of tempered glasses, such as those used in the automotive and architectural fields. The second one consists of thermoset polymers, typically used as matrices in fiber reinforced plastic structural composites. The birefringence of such resins is, in particular, exploited to investigate the development of swelling stresses and changes in fracture toughness as induced by water uptake…
Mental toughness in elite and sub-elite female soccer players
2017
Mental toughness (MT) is seen as an important psychological factor in the athletic success of elite athletes. Research on the subject has usually concerned male athletes. Our purpose was to investigate whether there are differences in mental toughness between female players who compete in an elite league and those who play at lower levels. In total, 298 female soccer players (M = 20.7 years, SD = 3.7 years) from three levels of Norwegian soccer responded to the Sports Mental Toughness Questionnaire. The MT Constancy subscale was removed from analysis due to an unacceptable Cronbach alpha (0.57). The results revealed that elite league players had significantly higher MT Global scores than th…
Development of Composites with a Self-Healing Function
2015
This research aimed to realize experimentally the facilevascular self-healing system in epoxy glass fibre reinforced composite. Using flexiblepolytetrafluoroethylene tubes as removable preforms, the channels were embeddedinto both neat epoxy resin and unidirectional glass-fibre reinforced epoxy laminate.Room temperature curable epoxy resin with a surfactant and an amine-basedhardener were the components of the binary healing agent. The specimens oftapered double cantilever beam geometry were subjected to Mode I fracture tests.Fracture of specimens released the healing agent from channels and triggeredself-healing process of the crack. Tested neat epoxy resin specimensdemonstrated recovery o…
Triatleters indre monolog : en studie som tar for seg hva som kjennetegner triatleters indre monolog under en konkurransesetting og om det er forskje…
2016
Masteroppgave i idrettsvitenskap - Universitetet i Agder 2016 The aim of this study is to survey the use of self-talk at triathletes. Are there any differences between the use of self-talk at triathletes with a high level of performance, compared to triathletes at a lower level of performance? There were a total of 20 participants in the study, where ten of them were athletes from the Norwegian national team of triathlon. These ten represented the participants of a high level of performance. The remaining ten, were club triathletes who represented the group with a lower level of performance. There were completed both frekvency, correlation- and regressionanalyses, and the result can be unde…
Toppdommerrollen i fotball : sammenhengen mellom angst og mental tøffhet og toppdommeres subjektive opplevelse av press i norsk fotball
2016
Masteroppgave i idrettsvitenskap - Universitetet i Agder 2016 Mental toughness, anxiety and pressure are well-used terms within sports, even though it can be difficult to understand the meaning of them. The purpose of this study was to examine the relationship between anxiety (cognitive- and somatic anxiety and self-confidence) and mental toughness, and top-class referees’ subjective experience on pressure as a soccer official. 183 top-class referees answered an online questionnaire. Mental toughness was measured by using the SMTQ and anxiety by using the CSAI-2. Of all the referees included in this study, 97.2% had been active footballers themselves, 44.3% had played on a high level. There…
Stress, angst og selvtillit i toppfotball : Hvilken betydning har mental tøffhet for angst og selvtillit i forkant av kampsituasjon blant fotballspil…
2017
Masteroppgave idrettsvitenskap ME517 - Universitetet i Agder 2017 Stress, anxiety and self-esteem are key concepts in sports psychology and performance. How these factors affect athletes in terms of achievement is an interesting area and the main background for this study. The purpose of this study was to investigate the meaning of mental toughness (MT) compared to cognitive anxiety, somatic anxiety and self-esteem ahead of soccer matches among high-level soccer players. The selection in this study was the first-team squad of Arendal fotball, consisting of 23 players from 18 to 37 years of age. During the project, Arendal fotball took part in the PostNord-league section four, which represen…