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Impact Testing (impact + testing)
Selected AbstractsImpact behavior of hybrid composite platesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2010Metin Sayer Abstract This experimental study deals with the impact response of hybrid composite laminates. Two different hybrid composite laminates, aramid/glass and aramid/carbon, and two different stacking sequences, such as [0/0/90/90]A+ [90/90/0/0]G for AG1 and [0/90/±45]A+ [±45/90/0]G for AG2 and so on (see Table I), were chosen for impact testing. The impact energy was gradually increased until complete perforation took place, and an energy profiling method (EPM) was used to identify the perforation thresholds of composites. The damaged samples were visually inspected. The images of the several samples subjected to various impact energies were registered and used for comparison and identifying damage mechanisms. The perforation thresholds for [0/90/±45]s aramid/glass and aramid/carbon laminates were found to be approximately 5% higher than those for their counterparts with the [0/0/90/90]s stacking sequence. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Increasing recyclability of PC, ABS and PMMA: Morphology and fracture behavior of binary and ternary blendsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Jan Rybnicek Abstract Binary and ternary blends of PC, ABS, and PMMA were studied. The blends were produced from original and recycled materials by melt mixing in a wide range of compositions. Instrumented Charpy impact testing, tensile testing, rheology investigations, and electron microscopy were carried out to determine the relationship between the deformation and fracture behavior, blend composition, morphology, and processing parameters. Resistance against unstable crack propagation was evaluated using the concepts of J -integral and crack-tip-opening displacement (CTOD). The transition from ductile elastic-plastic to brittle-linear elastic fracture behavior was observed in the case of PC/ABS/PMMA blend at 10% of PMMA. Reprocessing had only a slight influence on the deformation and fracture behavior of the recycled blends. The blends produced from recycled materials proved to be competitive with the original pure materials. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008 [source] The effect of the addition of poly(methyl methacrylate) fibres on some properties of high strength heat-cured acrylic resin denture base materialJOURNAL OF ORAL REHABILITATION, Issue 3 2003D. Jagger summary, The self-reinforcement of acrylic resin with butadiene styrene surface treated poly(methyl methacrylate) fibres has been reported to have the potential to substantially improve the transverse bend strength of conventional heat-cured acrylic resin. The aim of this study was to investigate the effect of the addition of butadiene styrene surface treated poly(methyl methacrylate) fibres in cross-ply arrangement to high impact acrylic resin on the transverse and impact strength. Specimens were prepared as specified in the International Standard Organization and British Standards for the Testing of Denture Base Resins (ISO 1567, 1988; BS 2487, 1989) and the British Standard Specification for Orthodontic resins (BS 6747, 1987) for transverse bend and impact testing. The impact strength was measured using a Zwick pendulum impact tester and the transverse bend strength measured using a Lloyds Instruments testing machine. The results showed that the impact strength was not improved with the addition of fibres, high impact acrylic resin with fibres (LF) 11·1 kJ m,2 and high impact acrylic resin (L) (12·5 kJ m,2). The modulus of rupture was decreased with the addition of fibres (57·8 MPa) for (LF) compared with (60·4 MPa) for (L). The modulus of elasticity was also reduced with the addition of fibres (1834·9 MPa) (LF) and 2086·2 MPa (L) as was the peak load (LF) (50·8 N) and (L) (55·8 N). It was concluded that the addition of surface treated poly(methyl methacrylate) fibres in cross-ply arrangement to high strength acrylic resin did not produce an improvement in the impact or transverse strength and cannot be recommended as a method of reinforcement. [source] Impact damage detection and degradation monitoring of wet GFRP composites using noncontact ultrasonicsPOLYMER COMPOSITES, Issue 8 2009K. Berketis Two different non-crimp glass fabrics with a polyester resin were used to produce laminated plates that were subjected to low velocity impact testing using three impact energy levels. The plates were immersed in water at 65°C for up to 24 months. The effectiveness of a traditional water coupled and an air-coupled ultrasonic C-Scan system was assessed in terms of damage size evaluation at various time intervals. The conditioned impacted plates were retested statically in compression to determine the residual strength for evaluation of damage tolerance. Weight change measurements revealed an initial increase due to water diffusion, followed by an extended decrease due to matrix dissolution at long-term immersion times. The use of water coupled pulse-echo ultrasonics proved ineffective after long-term water immersion as damaged areas became ultrasound-invisible. The contrast between impact damaged areas and water diffused areas was restored with the air-coupled C-scan. The macroscopic damage size was not affected by the long-term water immersion and the overall weight change while the residual compression strength was seemed to be dependent on the time of immersion and the size of the pre-existing impact damage. Calibrating the air-coupled system to a dry condition specimen, a good qualitative and quantitative indication of the degraded state of water immersed plates was obtained. This monitoring system for the degradation process seems to be very promising. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source] Damage evolution in low velocity impacted unreinforced vinyl ester 411-350 and 411-C50 resin systemsPOLYMER COMPOSITES, Issue 6 2000M. Motuku Assistant Professor Damage evolution in plaques made of vinyl ester resin systems was investigated as a function of specimen thickness, impact energy level and matrix material. Dow DERAKANE vinyl ester 411-350 and 411-C50 resin systems, which have low viscosity and are ideally suited for low-cost liquid processing techniques like vacuum assisted resin transfer molding (VARTM), were considered for the low velocity instrumented impact testing. Characterization of damage evolution was undertaken using optical microscopy and analysis of impact load histories recorded during the impact event. Radial cracking, perforations at the point of impact (in the form of a truncated cone), and damage resulting from the support constraints were identified as the dominant failure characteristics in both resin systems. Radial cracking, which originated from the bottom surface, was operative in all failed specimens and was attributed to the catastrophic failure due to extensive flexural tensile strength losses. For specimens that could deflect significantly, radial cracking and support-constraint-induced damage were the operative failure mechanisms. Radial cracking and through-thickness shearing led to failure in stiffer plaques. The DERAKANE 411-350-vinyl ester resin system was found more damage resistant than the 411-C50 system. [source] Questionnaire development: face validity and item impact testing of the Child Oral Health Impact ProfileCOMMUNITY DENTISTRY AND ORAL EPIDEMIOLOGY, Issue 2007Hillary L. Broder Abstract Objective:, The Child Oral Health Impact Profile (COHIP) was designed to assess oral-facial well-being in school-age children as reported by the child and via proxy report from a caregiver. This article describes the development of the COHIP using a multi-staged impact approach recommended by Guyatt et al. (Quality of life and pharmacoeconomics in clinical trials. Philadelphia, PA: Lippincott-Raven; 1996. p. 41). Methods:, There were multiple phases to the development of the questionnaire: (i) initial pool of items developed from the literature and expert review; (ii) face validity of items; (iii) impact evaluation of the initial item pool; (iv) development of positive items and face validity of new items; (v) impact evaluation of the revised questionnaire and (vi) factor analysis and final revision of the questionnaire. Factor analysis was completed on the final questionnaire using data from the impact evaluation in order to evaluate whether the COHIP measured independent conceptual domains. Results:, Factor analysis identified five domains: oral health, functional well-being, social/emotional well-being, school environment and self-image. Readability was calculated using the Flesch-Kinkaid readability score that was finalized at a 3.5 grade reading level. Finally, two response sets, and a revised format (e.g., including pictures, increasing font size, and shading every other item) were implemented to decrease respondent fatigue and increase accuracy of participant responses. Conclusions:, The final questionnaire consisted of 34 items and five conceptually distinct subscales: oral health, functional well-being, social/emotional well-being, school environment and self-image. Subsequent papers present the validity and reliability of the COHIP. [source] | |||||||||||||