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Compression Strength (compression + strength)
Selected AbstractsMicrostructure and Compression Strength of Novel TRIP-Steel/Mg-PSZ Composites,ADVANCED ENGINEERING MATERIALS, Issue 12 2009Horst Biermann Abstract Novel composites on basis of austenitic stainless TRIP-steel as matrix with reinforcements of Mg-PSZ are presented. Compact rods were produced by cold isostatic pressing and sintering, square honeycomb samples by the ceramic extrusion technique. The samples are characterized by optical and scanning electron microscopy before and after deformation, showing the microstructure and the deformation- induced martensite formation. The mechanical properties of samples with 5,vol% zirconia are superior compared to zirconia-free samples and composites with higher zirconia contents in terms of bending and compression tests. The honeycomb samples exhibit extraordinary high specific energy absorption in compression. [source] Calcium Phosphate-Based Resorbable Ceramics: Influence of MgO, ZnO, and SiO2 DopantsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2006Amit Bandyopadhyay Resorbable calcium phosphate (CaP)-based biomaterials are important because they can significantly improve health care by shortening the time necessary for restoration of functional loading of grafted bones. Although synthetic CaPs show exceptional similarities to natural bone, however, they are deficient in one major area, in that they do not have the same mineral content of bone. The focus of our work is to understand the influence of dopants on the physical, mechanical, and biological properties of tricalcium phosphate (TCP) resorbable ceramics with special emphasis toward in vitro strength degradation and cell,materials interactions as a function of time. For this purpose, ,-TCP was doped with magnesia (MgO), zinc oxide (ZnO), and silica (SiO2). Those dopants were added as individual dopants, and their binary and ternary compositions. It was found that these dopants significantly influenced densification behavior and as sintered microstructures of TCP. In vitro mineralization studies in simulated body fluids (SBF) for 12 weeks showed apatite growth on the highly porous compositions either on the surface or inside. From scanning electron microscopic analysis it was evident that surface degradation occurred on all compositions in SBF. Compression strengths for samples up to 12 weeks in SBF showed that it is possible to tailor strength loss behavior through compositional modifications. The highest compression strength was found for binary MgO,ZnO doped TCP. Overall, samples showed either a similar strength level during the 12 weeks test period, or a continuous decrease or a continuous increase in strength depending on dopant chemistry or amount. In vitro human osteoblast cell culture was used to determine influence of dopants on cell-materials interactions. All samples were non-toxic and biocompatible. Dopant chemistry also influenced adhesion, proliferation, and differentiation of osteoblastic precursor cell line 1 (OPC1) cells on these matrices. [source] Novel TRIP-Steel/Mg-PSZ Composite,Open Cell Foam Structures for Energy AbsorptionADVANCED ENGINEERING MATERIALS, Issue 3 2010Christos G. Aneziris Porous materials have received extensive attention for energy absorption in the last years. In terms of this study austenitic TRIP-steel/Mg-PSZ composite,open cell foam structures are formed based on replicas using open-celled polyurethane foam as a skeleton with and without a supporting dense face (jacket) coating. Their compression strength as well as their specific energy absorption SEA has been registered as a function of the compressive strain. The zirconia addition has reinforced the composite material with the face coating up to a compressive strain of 50%. The stress-induced martensitic transformation of partially stabilized zirconia phases has been investigated as a function of the compressive strain by EBSD. The zirconia phase transformation is triggered already at low compressive strains below 2%. [source] SiOC Ceramic Monoliths with Hierarchical PorosityINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 4 2010Cekdar Vakifahmetoglu SiOC glass monoliths possessing hierarchical porosity were produced by a one-pot processing method. Periodic mesoporous organosilica (PMO) particles were embedded into a foamed siloxane preceramic polymer. After pyrolysis at 1000°C in inert atmosphere, open celled, permeable SiOC ceramic monoliths with a high amount of pores, ranging in size from hundred of micrometers to a few nanometers, were obtained. The components possessed a specific surface area of 137 m2/g, indicating the retention of most of the mesopores after the pyrolytic conversion of the PMO precursor particles. These fillers converted to truncated rhombic dodecahedral SiOC mesoporous micron-sized grains, homogeneously distributed throughout the SiOC cellular matrix. The produced porous ceramics possessed compression strength of about 1.7 MPa, which is adequate for their use in several engineering applications. [source] Calcium phosphate cement reinforced by polypeptide copolymersJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2006Jiaping Lin Abstract Water-based calcium phosphate with bone repairing capability was reinforced by polypeptide graft copolymers and micelles that were formed by polypeptide copolymers. The mechanical studies showed that the compression strength and fracture energy of the calcium phosphate cement (CPC)/polypeptide composites are appreciably higher than those of CPC. The molecular structure of the polypeptide graft copolymers and the association form of the polypeptide copolymers exhibit a marked effect on the mechanical properties of CPC/polypeptide composites. The polypeptide copolymers with more hydrophilic side chains and with core-shell micelle forms have more effective reinforcement effect. The morphological studies based on the scanning electron microscope (SEM) observations revealed that both polypeptide graft copolymers and polypeptide copolymer micelles are well dispersed in CPC matrix. According to the obtained experimental results, reinforcement mechanism was suggested. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] Finite element analysis of vent/hand hole designs for corrugated fibreboard boxesPACKAGING TECHNOLOGY AND SCIENCE, Issue 1 2007Jongkoo Han Abstract Corrugated fibreboard is an economical and efficient material for fabricating shipping containers that are widely used for the distribution, transportation and storage of goods. Corrugated fibreboard is usually considered to be an orthotropic material because the principal fibre directions, machine direction (MD) and cross-machine direction (CD), are identical to the fibres in paperboard, which has apparent directional property differences. The purpose of this study is to investigate the principal design parameters of ventilation holes and hand holes in the faces of the shipping container, (corrugated fibreboard boxes), using finite element analysis (FEA). Various designs of ventilation holes were studied with respect to stress distribution and stress level. It was found that the appropriate pattern and location of the ventilation holes were vertical oblong-shaped and symmetrically positioned within a certain extent of distance to the right and left from the centre of the front and rear faces of the boxes. On the other hand, the appropriate location and pattern of the hand holes were a short distance from the centre to the top of the boxes on both side faces. The appropriate pattern was a modified shape, such as the radius of curvature of both sides in horizontal oblong. The pattern and location of both the ventilation holes and the hand holes determined by the FEA simulation generally agreed well with laboratory experimental results. The decrease in compression strength of the box could be minimized with identical area of the ventilation holes if the length of the major axis of the ventilation hole is less than 1/4 of the depth of the box and the ratio of the minor axis to the major axis is 1/3.5,1/2.5, provided that even-numbered holes are located symmetrically. Copyright © 2006 John Wiley & son, Ltd. [source] Moisture-induced effects on stacking strength of moulded-fibre packaging in varying environmental conditionsPACKAGING TECHNOLOGY AND SCIENCE, Issue 5 2004Gitte Sørensen Abstract Stacking strength of moulded-fibre trays was investigated as both compressional creep and static compression strength at constant and varying humidity conditions. The compressional creep behaviour resembled that of other paper and board containers and was accelerated at humidity cycling between 33% and 94% relative humidity (r.h.) for 18 days compared to constant humidity conditions 91% and 94% r.h. Although the moulded-fibre trays did not experience failure, secondary creep rate was accelerated by a factor of 10,20 and total creep strain by a factor of 1.3,1.6. Compressional creep was thus affected by mechanosorption, whereas static compression was found not to respond to cycling of environmental humidity. Static compression strength was merely determined by the moisture content of the moulded-fibre material. The effect of varying temperature on tray moisture content was examined by transfer of the moulded-fibre tray from preconditioning at cold storage (5°C, 59% r.h.) to ambient conditions (25°C, 54%). When a food simulant [agar gel, water activity (aw) ,1] was sealed inside the moulded-fibre tray, moisture condensed on the tray outer surface (moisture gain 1.4,g/100,g dry fibre) within 40,min of transfer, contrary to when empty moulded-fibre trays were exposed to same conditions. Condensation could thus potentially induce a large initial creep deformation of the moulded-fibre tray. Copyright © 2004 John Wiley & Sons, Ltd. [source] Moisture sorption in moulded fibre trays and effect on static compression strengthPACKAGING TECHNOLOGY AND SCIENCE, Issue 4 2003Gitte Sørensen Abstract This study provides a basic understanding of moisture sorption in moulded fibre packaging for food at varying environmental temperatures and humidities, and the resultant effects on static compression strength. The Guggenheim,Anderson,de Boer (GAB) model is used successfully to construct moisture sorption isotherms in the range 2,25°C and 33,98% relative humidity (% r.h.) (R2 = 0.949,0.999), in which moisture content varies from 5.4 to 28.3,g/100,g dry fibre. Static compression strength (SCS) is substantially affected by changes in moisture content of moulded fibre and decreases exponentially with increasing moisture content. The results indicate a minor hysteresis effect on static compression strength. For adsorption of moisture, a relative strength measure, % SCS (experimental SCS in kg divided by a standard SCS in kg), is given by % SCS = 13.83 + 166.50,·,e,0.0978,m (m is moisture content). The temperature dependence of moisture adsorption is incorporated in the GAB model by relating GAB coefficients, m0 and C, exponentially to temperature, T. By combining this with the exponential model for % SCS, static compression strength can be predicted directly from the surrounding temperature and humidity. Illustrated in a response surface plot the effects of changes in the surroundings are simple and readily accessible, e.g. for packaging designers and sales people. It is noted that an increase in humidity from 50% r.h. to 95% r.h. at constant temperature results in a drastic reduction in % SCS from 100% to 40%, whereas the temperature effect is typically less than 10% SCS when reducing temperature from 25°C to 2°C. Copyright © 2003 John Wiley & Sons, Ltd. [source] Cu/Ti base multicomponent amorphous Cu47Ti33Zr11Ni8Si1 and nanocrystalline silver compositesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2010Jan Dutkiewicz Abstract An easy glass-forming alloy based on Cu,Ti of composition Cu47Ti33Zr11Ni8Si1 was ball milled for 40,h to obtain amorphous powder. X-ray diffraction and differential scanning calorimetry (DSC) measurements confirmed the dominant presence of the amorphous phase after ball milling. However, transmission electron microscopy from powders allowed identification of Si particles and intermetallic phases a few nanometre in diameter, often of CuNi2Ti or Cu,Ti structures. The powder was then hot pressed in vacuum at temperature of 460,°C between the glass transition and the crystallization point to form bulk amorphous samples. Composites were prepared in the same way from mixed milled amorphous powders and nanocrystalline silver powder prepared by ball milling. Various ratios of amorphous to silver powder were applied with a maximum of 60% of nanocrystalline silver The microhardness of the amorphous phase component was near 1100,HV, much higher than the 90,HV of silver. Composites containing 20% of nanosilver have shown a much higher compression strength of 850,MPa, as compared to the 450,MPa of the composite containing 60% of silver, however, the latter has better ductility, near 5%, before fracture. [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] Versuche zur Tragfähigkeit von Ankerplatten mit einbetonierten Kopfbolzendübeln in schmalen StahlbetonstützenBETON- UND STAHLBETONBAU, Issue 6 2010Stephan Fromknecht Dr.-Ing. Versuche; Befestigung Abstract Müssen große Lasten von Stahl- in Betonbauteile eingebracht werden, sind Ankerplattendetails mit aufgeschweißten Kopfbolzendübeln oft praktikable Lösungen. Dies gilt auch für die Befestigung von Stahlträgern an Stützen aus Stahlbeton. Hier können die Ankerplatten z. B. bauseits an der Schalung befestigt und mit dem Ortbeton einbetoniert werden. Die Dimensionierung dieser Einbauteile kann, wie auch die Berechnung von nachträglich installierten Befestigungsmitteln, derzeit nach Europäischen Technischen Zulassungen (ETA) erfolgen. Im Unterschied zu nachträglich installierten Befestigungen ist für die Ankerplatte mit einbetonierten Kopfbolzendübeln eine rechnerische Nutzung der Tragfähigkeit der Bewehrung möglich. Allerdings führen die diesbezüglichen Regelungen , im Vergleich zu den in den Versuchen ermittelten Tragfähigkeiten , rechnerisch zu stark eingeschränkten Tragfähigkeiten. Dies beruht einerseits auf der Reduktion der Tragfähigkeit wegen geringer Randabstände und andererseits auf der stark eingeschränkten Nutzbarkeit der Bewehrung. Im folgenden Beitrag werden Versuchsergebnisse vorgestellt, welche den Einfluss der Betondruckfestigkeit, der Verankerungslänge, der Lastexzentrizität sowie der Bewehrungsmenge und -position auf das Versagensgeschehen und die Tragfähigkeit zeigen. Results of Experimental Investigations on the Load-Bearing Capacity of Steel Anchor Plates with in Concrete Encased Headed Studs in Reinforced Narrow Concrete Columns Anchor plates with welded shear studs are often used to transfer high loads from steel to reinforced concrete elements. This is for example the case for the fixation of steel beams to reinforced concrete columns. The anchor plates are fixed on site on the formwork and cast in-place in the concrete. The design is calculated according to European Technical Approvals like the design of post-installed anchors. In contrast to post-installed fastenings, the utilisation of the reinforcement of in concrete encased headed studs is theoretically possible. But the regulations of the ETAs lead to great reductions in the analysed load-bearing capacities compared to the capacities, obtained in tests. These tests have been conducted to investigate the load bearing behaviour and failure modes of anchor plates, especially in narrow reinforced concrete columns. In the following article the results of the experimental investigations are presented, which show the influence of concrete compression strength, shear stud length, load eccentricity as well as amount and position of reinforcement. [source] Experimentelle Untersuchungen zum Schubtragverhalten dünner Scheiben aus Ultrahochfestem Beton,BETON- UND STAHLBETONBAU, Issue 9 2009Julia Heidrich Dipl.-Ing. Versuche; Baustoffe Abstract Ultrahochfester Beton ist ein Baustoff mit herausragenden mechanischen Eigenschaften. Weit gespannte Brückentragwerke mit schlanken Stegen aus Ultrahochfestem Beton sind denkbar. Dadurch kann Eigengewicht und Material gespart werden. Die Lebensdauer der Brücken würde aufgrund der Widerstandsfähigkeit gegen mechanische und chemische Einflüsse steigen. Die Zug- und die Druckfestigkeit wurden inzwischen in einigen Forschungsarbeiten untersucht. Demgegenüber gibt es noch kaum Erkenntnisse zum Schubtragverhalten. Auch existieren noch keine Normen oder Vorschriften dazu. Eine Arbeit am Institut für Betonbau der TU-Graz befasst sich mit der Schubtragfähigkeit von schlanken, nicht beulgefährdeten Scheiben aus Ultrahochfestem Beton. Shear Carrying Capacity of Ultra High Performance Concrete Ultra High Performance Concrete is a building material with fantastic mechanical properties. Slender, durable Bridges with large spans and thin webs are imaginable. The life cycle will increase because of the chemical and mechanical resistance. The tension and compression strength are well investigated, but there are less investigations about the shear carrying capacity. One research work at the Institute for Structural Concrete of Graz University of Technology deals with the shear carrying capacity of thin Panels without buckling risk. [source] In vivo investigations on composites made of resorbable ceramics and poly(lactide) used as bone graft substitutesJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 6 2001Anita A. Ignatius Abstract Porous composites made of poly(L, DL-lactide) (PLA) and ,-tricalcium phosphate (,-TCP) or the glass ceramic, GB14N, respectively, were investigated in a loaded implant model in sheep. Six, 12 and 24 months after implantation histological and biomechanical evaluation were performed and compared to autogenous bone transplants. No significant differences were observed between the composites. After 6 months, the interconnecting pores of the ,-TCP-composite and the GB14N-composite were filled with newly formed bone (14 ± 5% or 29 ±15% of the implant, respectively) and soft tissue (30 ±9% or 21 ±12% of the implant, respectively). Only a mild inflammatory response was observed. The reaction was similar after 12 months. However, after 24 months a strong inflammatory reaction was seen. The newly formed bone was partly osteolytic. The adverse reaction occurred simultaneously to a significant reduction of the PLA component. The histological results were reflected by the biomechanical outcomes. Both composites showed compression strengths in the range of the autologous bone graft until 12 months of implantation. After 2 years, however, the strengths were significantly decreased. It is concluded that the new composites cannot yet be used for clinical application. An improvement in biocompatibility might be reached by a better coordination of the degradation times of the polymer and the ceramic component. © 2001 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 58: 701,709, 2001 [source] | |||||||||||||