Academic literature on the topic '4-point bending test'

Presented article deals with the influence of PET fiber production on the bending strength of cement-based composite when incorporated into the fresh mortar, and comparison of results of 3-point and 4-point bending test. Cement paste samples were reinforced with 2 wt. % of primary or recycled PET fibers. The bending test was performed on prismatic samples with dimension of 40 × 40 × 160 mm. It was found that samples with recycled PET fibers, compared to primary ones, exhibit a decrease in bending strength. In the case of 4-point bending tests, the samples with recycled PET fibers exhibited higher bending strength than reference samples without any fibers. However, in the case of 3-point bending tests, the samples with recycled PET fibers had lower bending strength than the reference ones. The results suggest that recycled PET fibers could be used as an alternative to reinforce cement-based composites.

The goal of the work was to evaluate mechanical performance of full-scale timber beams containing scarf joint with a dowel. Work focused on standard testing using modular system to obtain effective stiffness and strength of the beams with and without the joint. The work further researched a contact zone between two timber parts of the joint – at the scarf face. This was carried out using non-destructive optical technique – digital image correlation (DIC) and newly developed algorithm. The joint was made of Norway spruce, dims. 6×0.2×0.24 m and was loaded by two modes: a) 3-point bending and b) 4-point bending. During the loading, a sequence of images was acquired for further investigation of contact zone using the proposed algorithm. The joint with scarf and dowel provided enough effective stiffness, ie. 73–93% for 3-point bending test and 71% for 4-point bending with respect to MOE measured on reference solid beams. Effective strength of the joint was also relatively high and in a range of 55% and 60% with respect to reference solid beams in both 3-point and 4-point bending tests. Contact length differed for loading modes. Mean contact length in symmetrical 4-point bending was about 40%, for asymmetrical 3-point bending test, it was approx. 20% on face closer to support and 44% on a face closer to loads.

An improved means of obtaining the elastic constants of component-lead-board assemblages from two three-point bending tests and one four-point torsion test is proposed. The suggested method models the three-point bending test as an orthotropic plate and uses the experimentally obtained bending and torsion results in a standard nonlinear least square procedure to determine the rigidities in the x and y directions and the Poisson’s ratios directly. Numerical simulation of the method indicates that the beam model overestimates the elastic modulii by 4 to 7 percent and the corresponding rigidities by 7 to 13 percent.

Graphenes have aroused great interest among the scientists lately, due to their special physical properties which are supposed to be transferred to composite materials [1,2,3,6]. Some polymers show low mechanical properties which can be improved by adding various types of materials [9,13]. Using nanoparticles, an enhancement of mechanical, thermal and electrical properties can be obtained, even for small contents of additives [10,11,12,14,15,16]. The evaluation of mechanical properties of polymer composites with graphene can be achieved relying on the three-point bending tests [4]. This work presents a few conclusions resulting from the three points bending tests of the polyester composites with graphene and graphite [7,8].

The 4-point bending test is a widely used method to determine material parameters. No commonly accepted evaluation methodology is available for materials showing non-linear deformation mechanisms. In the present study micro- and macro-mechanical simulation models of continuously reinforced metal matrix composites are employed to investigate thermo-elasto-plasticity and creep in such experiments. The overall deflection behavior and the underlying mechanisms are identified revealing the interaction of various micromechanical phenomena. Comparisons to a set of experimental results are presented.

Disertační práce se zabývala vlivem adheze mezi vláknovým (FRC) a částicovým (PFC) kompozitem a složením obou komponent na mechanické vlastnosti a způsob porušování modelových bi-materiálových kompozitních těles při statickém namáhání. Zkoumán byl také vliv způsobu přípravy bi-materiálového kompozitního tělesa na pevnost adheze mezi jeho kompozitními komponentami. K hodnocení mechanických vlastností bi-materiálových PFC/FRC těles byl použit jak 3 tak 4-bodový ohybový test za pokojové teploty a relativní vlhkosti 70%. Modifikovaný vytrhávací test byl použit k měření smykové pevnosti adheze mezi vláknovým a částicovým kompozitem. Tyto výsledky byly korelovány s výsledky ze strukturní a fraktografické analýzy (TGA, SEM). Experimentální data byla poté analyzována pomocí existujících mikromechanických modelů a byl nalezen vztah mezi tuhostí modelových bi-materiálových těles, složením a geometrií uspořádání jejich komponent a pevností adheze mezi těmito komponentami. Na základě těchto výsledků byl navržen optimální způsob vrstvení a přípravy PFC/FRC bimateriálových těles. Navržené postupy byly použity k přípravě a pre-klinickým testům nosných konstrukcí zubních můstků.

Auf der Basis der Bemessungsgrundlagen (DAfStb-Richtlinie „Stahlfaserbeton“, DBV-Merkblatt „Stahlfaserbeton“ und DIN 1045-1) wurden ausgewählte Bauteilversuche mit entsprechenden rechnerischen Überprüfungen der experimentell ermittelten Ergebnisse durchgeführt. Die Untersuchungen konzentrierten sich auf die Ermittlung der Effizienz von ausgewählten Stahlfasern in Betonen mit und ohne Betonstahlbewehrung in durch Biegung ohne Längskraft belasteten Versuchskörpern unter Betrachtung der Grenzzustände der Gebrauchstauglichkeit (GZG) und Tragfähigkeit (GZT). Das Versuchsprogramms umfasste neben der Prüfung ausgewählter Frischbetoneigenschaften die Bestimmung von Festbetonparametern an standardisierten Probekörpern. Des Weiteren wurden 4-Punkt-Biegezugversuche an Balken mit den Abmessungen l/h/b = 70/15/15 cm aus reinem Stahlfaserbeton sowie stahlfaserbewehrtem Stahlbeton, in Anlehnung an das DBV-Merkblatt „Stahlfaserbeton“ und die Richtlinie „Stahlfaserbeton“ vom DAfStb, durchgeführt. Aufbauend auf den Erkenntnissen aus den Materialversuchen im Labormaßstab wurden anschließend Untersuchungen an großformatigen Biegebalken (l/h/b = 420/40/20 cm) durchgeführt. Im Weiteren erfolgten Prüfungen und Auswertungen von Einzelfaserausziehversuchen mit ausgewählten Stahldrahtfasern in Verbindung mit Betonen unterschiedlicher Druckfestigkeit unter Berücksichtigung des Einflusses der Einbindelänge sowie des Einbindewinkels. Im Rahmen des Versuchsprogramms wurden die auf der Grundlage der 4-Punkt-Biegezugversuche ermittelten Ergebnisse analysiert und mit dem derzeit gültigen Bemessungsmodell nach DAfStb-Richtlinie „Stahlfaserbeton“ rechnerisch überprüft. Auf der Basis dieser Ergebnisse erfolgte die Entwicklung eines Ansatzes zur Optimierung der bestehenden Bemessungsansätze. Gegenstand dieser Forschungsarbeit war ebenfalls die Entwicklung eines Fasermodells, mit dem man auf der Grundlage des eingesetzten Fasergehaltes und der Faserart Rückschlüsse auf die Faseranzahl in einer rechteckigen Bruchfläche ziehen kann. Hierbei wurde ein Modell für Rechteckquerschnitte entwickelt, welches es ermöglicht, die durchschnittliche Faseranzahl in einer Bruchfläche, auf der Basis vereinfachter Annahmen, abzuschätzen. Die Verifizierung des Modells erfolgte durch den Vergleich der errechneten Faseranzahl mit zahlreichen experimentellen Versuchsergebnissen. Im letzten Abschnitt dieser Arbeit wurde die Herleitung bzw. Generierung von Bemessungshilfsmitteln zur Biegebemessung von Stahlfaserbeton mit und ohne Betonstahlbewehrung behandelt. Die Ausführungen beziehen sich dabei auf dimensionslose Bemessungstafeln und Interaktionsdiagrammen für Rechteckquerschnitte.

L'objectif de ce travail est d'établir des relations entre chimie d'interface et propriétés mécaniques dans les assemblages bimétalliques. Il met en évidence que les mécanismes qui contrôlent le développement d'une interface entre alliage Al-Si et renfort ferreux ou titane ont une influence majeure sur les propriétés mécaniques de cette interface. La caractérisation mécanique des interfaces est réalisée par un test de flexion 4 points sur des lames bimétallique élaborées par aluminiage au trempé sur lesquelles un raidisseur est rapporté par collage ou surmoulage. L'évolution de la chimie de la zone de réaction interfaciale est provoquée par un traitement thermique à 535°C à différents temps. La caractérisation des zones de réaction ainsi que des chemins de fissuration est réalisée par diffraction des rayons X et microsonde électronique. Pour les interfaces Fe/A-S7G03 brutes d'élaboration, avant traitement thermique, l'analyse des essais mécaniques conduit à l'obtention d'une valeur du taux de restitution d'énergie de 23 J/m2 qui correspond à la propagation d'une fissure dans la phase η−Al5Fe2(Si). En ce qui concerne les interfaces Ti/A-S7G03, leur force n'a pas permis la propagation d'une fissure dans les conditions de l'essai. A la suite d'un traitement thermique à 535°C, les interfaces Fe/A-S7G03 sont fragilisées par le mécanisme de croissance de la couche de réaction interfaciale qui conduit à l'apparition de porosités Kirkendall en son sein. A l'inverse, dans le cas des interfaces Ti/A-S7G03, aucun affaiblissement de l'interface n'est associé au traitement thermique en raison d'un mécanisme de croissance différent.

One of the major health problems in western societies is back pain, with a prevalence rate of 49%–80%. In many cases, the back pain is due to degenerated discs. The gold standard to treat a severely degenerated disc is spinal fusion, where the vertebral disc is replaced with a cage structure. However, fusion cages have a failure rate of 30%, hence the need for further development. The focus of this thesis is to evaluate the combination of calcium phosphate cement with titanium, for a spinal application. Mechanical tests in the form of tensile, compression and 4-point-bending were performed to study the different material properties. The obtained results was applied as material parameters for isotropic linear elastic material models, using ANSYS. This was then used to develop a cage design through topology optimisation which was further evaluated by using Finite Element Analysis. From the tensile testing of the titanium, isotropic behaviour was found. It was also found that a longer mixing time of the cement resulted in poorer mechanical properties of the calcium phosphate, however, no conclusive results were obtained from the 4-point-bending tests. The final cage geometry filled with calcium phosphate was tested under compression to see whether the cage could protect the calcium phosphate or not. MicroCT after the test confirmed that no larger cracks developed during the testing, suggesting that the cage is strong enough to protect the calcium phosphate from mechanical failure.

Auf der Basis der Bemessungsgrundlagen (DAfStb-Richtlinie „Stahlfaserbeton“, DBV-Merkblatt „Stahlfaserbeton“ und DIN 1045-1) wurden ausgewählte Bauteilversuche mit entsprechenden rechnerischen Überprüfungen der experimentell ermittelten Ergebnisse durchgeführt. Die Untersuchungen konzentrierten sich auf die Ermittlung der Effizienz von ausgewählten Stahlfasern in Betonen mit und ohne Betonstahlbewehrung in durch Biegung ohne Längskraft belasteten Versuchskörpern unter Betrachtung der Grenzzustände der Gebrauchstauglichkeit (GZG) und Tragfähigkeit (GZT). Das Versuchsprogramms umfasste neben der Prüfung ausgewählter Frischbetoneigenschaften die Bestimmung von Festbetonparametern an standardisierten Probekörpern. Des Weiteren wurden 4-Punkt-Biegezugversuche an Balken mit den Abmessungen l/h/b = 70/15/15 cm aus reinem Stahlfaserbeton sowie stahlfaserbewehrtem Stahlbeton, in Anlehnung an das DBV-Merkblatt „Stahlfaserbeton“ und die Richtlinie „Stahlfaserbeton“ vom DAfStb, durchgeführt. Aufbauend auf den Erkenntnissen aus den Materialversuchen im Labormaßstab wurden anschließend Untersuchungen an großformatigen Biegebalken (l/h/b = 420/40/20 cm) durchgeführt. Im Weiteren erfolgten Prüfungen und Auswertungen von Einzelfaserausziehversuchen mit ausgewählten Stahldrahtfasern in Verbindung mit Betonen unterschiedlicher Druckfestigkeit unter Berücksichtigung des Einflusses der Einbindelänge sowie des Einbindewinkels. Im Rahmen des Versuchsprogramms wurden die auf der Grundlage der 4-Punkt-Biegezugversuche ermittelten Ergebnisse analysiert und mit dem derzeit gültigen Bemessungsmodell nach DAfStb-Richtlinie „Stahlfaserbeton“ rechnerisch überprüft. Auf der Basis dieser Ergebnisse erfolgte die Entwicklung eines Ansatzes zur Optimierung der bestehenden Bemessungsansätze. Gegenstand dieser Forschungsarbeit war ebenfalls die Entwicklung eines Fasermodells, mit dem man auf der Grundlage des eingesetzten Fasergehaltes und der Faserart Rückschlüsse auf die Faseranzahl in einer rechteckigen Bruchfläche ziehen kann. Hierbei wurde ein Modell für Rechteckquerschnitte entwickelt, welches es ermöglicht, die durchschnittliche Faseranzahl in einer Bruchfläche, auf der Basis vereinfachter Annahmen, abzuschätzen. Die Verifizierung des Modells erfolgte durch den Vergleich der errechneten Faseranzahl mit zahlreichen experimentellen Versuchsergebnissen. Im letzten Abschnitt dieser Arbeit wurde die Herleitung bzw. Generierung von Bemessungshilfsmitteln zur Biegebemessung von Stahlfaserbeton mit und ohne Betonstahlbewehrung behandelt. Die Ausführungen beziehen sich dabei auf dimensionslose Bemessungstafeln und Interaktionsdiagrammen für Rechteckquerschnitte.

碩士
國防醫學院
牙醫科學研究所
97
Abstract The typical orthodontics treatments for adjusting the odontoparallaxis to the ideal position are by continuous force strengthening which may cause some uncomfort. The characteristics of NiTi alloy archwires are shape memory and superelasticity. Shape memory effect is caused with the temperature changed within the material phase. While the material is forced by strength it can stand, the superelasticity will be caused. However, material will return to its original shape when unloading. Elastic modulus is the fundamental parameter for measuring the material. The measurements which researchers usually operate for testing the quality of material are static. However, materials can’t manifest under the changeable oral environment with the static measurement. Because there are too many products of NiTi archwires for clinician to choose with, who usually rely on the information which provided by the manufacturer. The way of choosing the right archwires has great connection with the brands of Orthodontic. However, the elastic modulus, phase transformation temperature, surface roughness will differ according to the different brand of NiTi archwires. This report is focus on three brands of NiTi archwires which orthodontist are used to operate, they are 0.016 and 0.014 inch archwires, which are used for testing the phase transformation temperature with differential scanning calorimetry. Besides, the three general clinical 0.014 inch archwires attached with 0.022 slot bracket for testing NiTi alloy archwires. Applying the clinical treatment with 4-point bending test, the first one for comparing the elastic modulus differs with the use of Dynamic Mechanical Analyzer. Finally, verifying the result of my experiment about materials composition and surface roughness, and the result can be provided to clinician. From the experimental statistic analysis I conclude that, 1.There are apparently temperature varies according with the differences of NiTi phase. The highest one is Neo Sentalloy F80, the second one is Damon, and the last one is Orthonol. 2. The phase transformation temperature varies according with the length of diameter, and the result is 0.016 inches higher than 0.014 ones. 3. From the composition analyzing, I discover there are elements of iron and copper in Damon, and cobalt in Orthonol, but not any elements which can cause R-phase in Sentalloy. 4.Under the environment of air and artificial saliva substitute, applying 4-point bending to test the elastic modulus and finds out there is no significant differences in the values. 5. At the temperature of 37°C, matching different brand of NiTi archwires with brackets to test if the elastic modulus will be affected with the different clinical experimental modes. And the answer is that there is no significant difference according to the match. Mode 1, the average highest elastic modulus is with the match of In-Ovation C orthodontics and the Orthonol NiTi alloy archwires. Mode 2, the average highest elastic modulus is with the match of In-Ovation C orthodontics and the Damon NiTi alloy archwires. And the lowest one is Synergy orthodontics with the Sentalloy NiTi alloy archwires. Mode 3, the highest elastic modulus is Damon orthodontics with Sentalloy NiTi alloy archwires. And the lowest match is Damon orthodontics withOrthonol NiTi alloy archwires. Mode 4, the highest elastic modulus is In-Ovation C orthodontics with the Damon NiTi alloy archwires. And the lowest match is Synergy orthodontics with Sentalloy NiTi alloy archwires. 6. for comparing the surface roughness between pre-test and test with 4-point bending discovers the roughness between brand of Sentalloy and Damon are apparently higher, but on Orthonol becomes lower.

Bones are multifunctional passive organs of movement that supports soft tissue and directly attached muscles. They also protect internal organs and are a reserve of calcium, phosphorus and magnesium. Each bone is covered with periosteum, and the adjacent bone surfaces are covered by articular cartilage. Histologically, the bone is an organ composed of many different tissues. The main component is bone tissue (cortical and spongy) composed of a set of bone cells and intercellular substance (mineral and organic), it also contains fat, hematopoietic (bone marrow) and cartilaginous tissue. Bones are a tissue that even in adult life retains the ability to change shape and structure depending on changes in their mechanical and hormonal environment, as well as self-renewal and repair capabilities. This process is called bone turnover. The basic processes of bone turnover are: • bone modeling (incessantly changes in bone shape during individual growth) following resorption and tissue formation at various locations (e.g. bone marrow formation) to increase mass and skeletal morphology. This process occurs in the bones of growing individuals and stops after reaching puberty • bone remodeling (processes involve in maintaining bone tissue by resorbing and replacing old bone tissue with new tissue in the same place, e.g. repairing micro fractures). It is a process involving the removal and internal remodeling of existing bone and is responsible for maintaining tissue mass and architecture of mature bones. Bone turnover is regulated by two types of transformation: • osteoclastogenesis, i.e. formation of cells responsible for bone resorption • osteoblastogenesis, i.e. formation of cells responsible for bone formation (bone matrix synthesis and mineralization) Bone maturity can be defined as the completion of basic structural development and mineralization leading to maximum mass and optimal mechanical strength. The highest rate of increase in pig bone mass is observed in the first twelve weeks after birth. This period of growth is considered crucial for optimizing the growth of the skeleton of pigs, because the degree of bone mineralization in later life stages (adulthood) depends largely on the amount of bone minerals accumulated in the early stages of their growth. The development of the technique allows to determine the condition of the skeletal system (or individual bones) in living animals by methods used in human medicine, or after their slaughter. For in vivo determination of bone properties, Abstract 10 double energy X-ray absorptiometry or computed tomography scanning techniques are used. Both methods allow the quantification of mineral content and bone mineral density. The most important property from a practical point of view is the bone’s bending strength, which is directly determined by the maximum bending force. The most important factors affecting bone strength are: • age (growth period), • gender and the associated hormonal balance, • genotype and modification of genes responsible for bone growth • chemical composition of the body (protein and fat content, and the proportion between these components), • physical activity and related bone load, • nutritional factors: – protein intake influencing synthesis of organic matrix of bone, – content of minerals in the feed (CA, P, Zn, Ca/P, Mg, Mn, Na, Cl, K, Cu ratio) influencing synthesis of the inorganic matrix of bone, – mineral/protein ratio in the diet (Ca/protein, P/protein, Zn/protein) – feed energy concentration, – energy source (content of saturated fatty acids - SFA, content of polyun saturated fatty acids - PUFA, in particular ALA, EPA, DPA, DHA), – feed additives, in particular: enzymes (e.g. phytase releasing of minerals bounded in phytin complexes), probiotics and prebiotics (e.g. inulin improving the function of the digestive tract by increasing absorption of nutrients), – vitamin content that regulate metabolism and biochemical changes occurring in bone tissue (e.g. vitamin D3, B6, C and K). This study was based on the results of research experiments from available literature, and studies on growing pigs carried out at the Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences. The tests were performed in total on 300 pigs of Duroc, Pietrain, Puławska breeds, line 990 and hybrids (Great White × Duroc, Great White × Landrace), PIC pigs, slaughtered at different body weight during the growth period from 15 to 130 kg. Bones for biomechanical tests were collected after slaughter from each pig. Their length, mass and volume were determined. Based on these measurements, the specific weight (density, g/cm3) was calculated. Then each bone was cut in the middle of the shaft and the outer and inner diameters were measured both horizontally and vertically. Based on these measurements, the following indicators were calculated: • cortical thickness, • cortical surface, • cortical index. Abstract 11 Bone strength was tested by a three-point bending test. The obtained data enabled the determination of: • bending force (the magnitude of the maximum force at which disintegration and disruption of bone structure occurs), • strength (the amount of maximum force needed to break/crack of bone), • stiffness (quotient of the force acting on the bone and the amount of displacement occurring under the influence of this force). Investigation of changes in physical and biomechanical features of bones during growth was performed on pigs of the synthetic 990 line growing from 15 to 130 kg body weight. The animals were slaughtered successively at a body weight of 15, 30, 40, 50, 70, 90, 110 and 130 kg. After slaughter, the following bones were separated from the right half-carcass: humerus, 3rd and 4th metatarsal bone, femur, tibia and fibula as well as 3rd and 4th metatarsal bone. The features of bones were determined using methods described in the methodology. Describing bone growth with the Gompertz equation, it was found that the earliest slowdown of bone growth curve was observed for metacarpal and metatarsal bones. This means that these bones matured the most quickly. The established data also indicate that the rib is the slowest maturing bone. The femur, humerus, tibia and fibula were between the values of these features for the metatarsal, metacarpal and rib bones. The rate of increase in bone mass and length differed significantly between the examined bones, but in all cases it was lower (coefficient b <1) than the growth rate of the whole body of the animal. The fastest growth rate was estimated for the rib mass (coefficient b = 0.93). Among the long bones, the humerus (coefficient b = 0.81) was characterized by the fastest rate of weight gain, however femur the smallest (coefficient b = 0.71). The lowest rate of bone mass increase was observed in the foot bones, with the metacarpal bones having a slightly higher value of coefficient b than the metatarsal bones (0.67 vs 0.62). The third bone had a lower growth rate than the fourth bone, regardless of whether they were metatarsal or metacarpal. The value of the bending force increased as the animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. The rate of change in the value of this indicator increased at a similar rate as the body weight changes of the animals in the case of the fibula and the fourth metacarpal bone (b value = 0.98), and more slowly in the case of the metatarsal bone, the third metacarpal bone, and the tibia bone (values of the b ratio 0.81–0.85), and the slowest femur, humerus and rib (value of b = 0.60–0.66). Bone stiffness increased as animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. Abstract 12 The rate of change in the value of this indicator changed at a faster rate than the increase in weight of pigs in the case of metacarpal and metatarsal bones (coefficient b = 1.01–1.22), slightly slower in the case of fibula (coefficient b = 0.92), definitely slower in the case of the tibia (b = 0.73), ribs (b = 0.66), femur (b = 0.59) and humerus (b = 0.50). Bone strength increased as animals grew. Regardless of the growth point tested, bone strength was as follows femur > tibia > humerus > 4 metacarpal> 3 metacarpal> 3 metatarsal > 4 metatarsal > rib> fibula. The rate of increase in strength of all examined bones was greater than the rate of weight gain of pigs (value of the coefficient b = 2.04–3.26). As the animals grew, the bone density increased. However, the growth rate of this indicator for the majority of bones was slower than the rate of weight gain (the value of the coefficient b ranged from 0.37 – humerus to 0.84 – fibula). The exception was the rib, whose density increased at a similar pace increasing the body weight of animals (value of the coefficient b = 0.97). The study on the influence of the breed and the feeding intensity on bone characteristics (physical and biomechanical) was performed on pigs of the breeds Duroc, Pietrain, and synthetic 990 during a growth period of 15 to 70 kg body weight. Animals were fed ad libitum or dosed system. After slaughter at a body weight of 70 kg, three bones were taken from the right half-carcass: femur, three metatarsal, and three metacarpal and subjected to the determinations described in the methodology. The weight of bones of animals fed aa libitum was significantly lower than in pigs fed restrictively All bones of Duroc breed were significantly heavier and longer than Pietrain and 990 pig bones. The average values of bending force for the examined bones took the following order: III metatarsal bone (63.5 kg) <III metacarpal bone (77.9 kg) <femur (271.5 kg). The feeding system and breed of pigs had no significant effect on the value of this indicator. The average values of the bones strength took the following order: III metatarsal bone (92.6 kg) <III metacarpal (107.2 kg) <femur (353.1 kg). Feeding intensity and breed of animals had no significant effect on the value of this feature of the bones tested. The average bone density took the following order: femur (1.23 g/cm3) <III metatarsal bone (1.26 g/cm3) <III metacarpal bone (1.34 g / cm3). The density of bones of animals fed aa libitum was higher (P<0.01) than in animals fed with a dosing system. The density of examined bones within the breeds took the following order: Pietrain race> line 990> Duroc race. The differences between the “extreme” breeds were: 7.2% (III metatarsal bone), 8.3% (III metacarpal bone), 8.4% (femur). Abstract 13 The average bone stiffness took the following order: III metatarsal bone (35.1 kg/mm) <III metacarpus (41.5 kg/mm) <femur (60.5 kg/mm). This indicator did not differ between the groups of pigs fed at different intensity, except for the metacarpal bone, which was more stiffer in pigs fed aa libitum (P<0.05). The femur of animals fed ad libitum showed a tendency (P<0.09) to be more stiffer and a force of 4.5 kg required for its displacement by 1 mm. Breed differences in stiffness were found for the femur (P <0.05) and III metacarpal bone (P <0.05). For femur, the highest value of this indicator was found in Pietrain pigs (64.5 kg/mm), lower in pigs of 990 line (61.6 kg/mm) and the lowest in Duroc pigs (55.3 kg/mm). In turn, the 3rd metacarpal bone of Duroc and Pietrain pigs had similar stiffness (39.0 and 40.0 kg/mm respectively) and was smaller than that of line 990 pigs (45.4 kg/mm). The thickness of the cortical bone layer took the following order: III metatarsal bone (2.25 mm) <III metacarpal bone (2.41 mm) <femur (5.12 mm). The feeding system did not affect this indicator. Breed differences (P <0.05) for this trait were found only for the femur bone: Duroc (5.42 mm)> line 990 (5.13 mm)> Pietrain (4.81 mm). The cross sectional area of the examined bones was arranged in the following order: III metatarsal bone (84 mm2) <III metacarpal bone (90 mm2) <femur (286 mm2). The feeding system had no effect on the value of this bone trait, with the exception of the femur, which in animals fed the dosing system was 4.7% higher (P<0.05) than in pigs fed ad libitum. Breed differences (P<0.01) in the coross sectional area were found only in femur and III metatarsal bone. The value of this indicator was the highest in Duroc pigs, lower in 990 animals and the lowest in Pietrain pigs. The cortical index of individual bones was in the following order: III metatarsal bone (31.86) <III metacarpal bone (33.86) <femur (44.75). However, its value did not significantly depend on the intensity of feeding or the breed of pigs.

Abstract The objective of this paper is to present a 4-point bend test of 5LPP (Five Layer Polypropylene) concrete coated pipe. This is the first of its kind of bend test for a complex coating combination of 5LPP and concrete layers. The bend tests have been carried out to simulate S-Lay installation loading conditions to assess the coating integrity of the pipeline during installation. This paper reports the test arrangements including instrumentation, load schedule, test procedure and the challenges involved. Finally, the preliminary results and conclusions of the tests are documented. Two separate full scale four-point bend tests are carried out to study the behavior of the 5LPP concrete coated pipe. The purpose of the first test is to understand the complex behavior of the 5LPP/CWC coated test pipe and validate previously made industry standard assumptions regarding the calculated coated joint stiffness. The purpose of the second test is to observe the coating integrity of the test joint and slippage behavior due to the simulated installation conditions (overbend and sagbend bending moments and/or corresponding curvatures). The nonlinear moment-curvature for the concrete coated pipe is estimated based on an analytical approach taking into consideration plane bending theory and slippage behavior of the coating layers. The moment-curvature is used to prepare the load schedule for the tests. The test string consists of a test joint (40ft) welded to half joints at the ends. The bend test is performed using industry established full scale 4-point bend test arrangements. A global finite element model is used to simulate the tests using the analytical moment-curvature of the concrete coated pipe. The stiffness of the test pipe is calculated using the first bend test and compared against the analytical stiffness. The second test is carried out by applying loads corresponding to an estimated maximum overbend bending moment and then the test string is unloaded and rebent in opposite direction by applying loads corresponding to an estimated maximum sagbend bending moment. The results of the second test are documented at each load step and the integrity of the coating is measured against specified concrete coating damage criteria for tension as well as compression. Finally, field observations from the actual installation operation are compared against the bend test results. Conclusions are presented to address various aspects of concrete coated pipe for S-Lay installations.

For the purpose of establishing fracture evaluation method of nickel based alloy weld of nuclear power plants, fracture tests using pipe models (8B and 14B for bending, 12B for inner pressure) with an alloy 132 weld joint have been performed at room temperature and high temperature (325°C). The predicted loads calculated by limit load evaluation method using the measured and code regulated flow stresses were compared with the maximum test loads. And the predicted bending loads of the pipes at 325°C (8B and 14B) and at room temperature (8B) with the initial surface crack whose depth is 75% of the pipe thickness were in good agreement with the maximum test loads. Also the predicted inner pressure of the pipe at room temperature (12B) agreed with the measured maximum pressure. Only for one case of the 14B pipe subjected to the bending load at room temperature, the predicted load by limit load evaluation method has 20% unconservative difference from the measured data, on the other hand, the predicted load by J-T analysis made this difference smaller and conservative.

An investigation of the low-cycle bending fatigue of spur gears made from AISI 9310 gear steel was completed. Tests were conducted using the single-tooth bending method to achieve crack initiation and propagation. Tests were conducted on spur gears in a fatigue test machine using a dedicated gear test fixture. Test loads were applied at the highest point of single tooth contact. Gear bending stresses for a given testing load were calculated using a linear-elastic finite element model. Test data were accumulated from 1/4 cycle to several thousand cycles depending on the test stress level. The relationship of stress and cycles for crack initiation was found to be semi-logarithmic. The relationship of stress and cycles for crack propagation was found to be linear. For the range of loads investigated, the crack propagation phase is related to the level of load being applied. Very high loads have comparable crack initiation and propagation times whereas lower loads can have a much smaller number of cycles for crack propagation cycles as compared to crack initiation.

The results of a recent ice indentation series, along with a 4-point beam bending series, are analysed in the present paper with regard to time-dependent fracture. The beam bending series used a a 4-point apparatus to test the effects of velocity on fracture toughness, and to study time delayed fracture at loading rates below the fracture strength of ice. The indentor series used different indentors (diameters ranging from 10 mm to 70 mm), and applied various velocities used to test the time-dependent fracturing of ice. For experiments with a low ratio of velocity to indentor showed damaged-enhanced creep behaviour, ending in large, global failure during some tests. For the highest velocity tests, the ice showed increasingly brittle failure. The loading curve in these tests displayed many smaller spalling events, or ice extrusion events, with cyclic ramp-up of loads between each event.

A series of collapse tests were performed on box girder models to evaluate the effect of collision damage on the residual longitudinal strength of the hull girder. The experiments were carried out under pure bending moment using, so-called 4-point bending test method, the load, deflection and strain were measured. Ten experimental models were fabricated, two of them were intact, four were plastically damaged and four were fracture damaged. To generate the damages, lateral collision tests were firstly performed on the box girder models. To consider the effects of ship speed and relative draft on extents of damage due to collision, the drop height and impact location of striker were changed for each model. Numerical analyses were also performed by applying nonlinear finite element analysis. In the numerical analysis, the measured initial imperfection data and the welding residual stresses were considered.

The strain capacity of pipes under combined loading is a significant research topic if the pipes are provided for Strain Based Design scenarios. Displacement controlled scenarios such as ground movements may significantly affect transmission pipelines by inducing large amounts of plastic axial strains, which need to be considered in the design process. For these combined loading cases with internal pressure combined with pronounced longitudinal strains from environmental conditions it is essential to evaluate critical deformations on the one hand and to conclude the required structural performance and material parameters, on the other hand. Also pipe laying procedures introduce axial strains in pipes and pipe strings, e.g. cold bending of pipes for onshore pipelines, or S-Laying of offshore pipelines in combination with external pressure. For these cases also the strain capacity of the pipes and pipe connections must be guaranteed. In any case, the structural behaviour needs to be checked via full-scale tests to confirm and validate engineering approaches and computational models. This paper presents a full-scale test series of UOE pipe X70 (OD = 914 mm, WT = 14.1 mm) and Spiral welded pipe X70 (OD = 1016 mm, WT = 20 mm) subject to internal pressure and bending load. Full-scale 4-point-bending tests on pipe joints subject to internal pressure were performed. The test series included the influence of girth weld, strip end weld for spiral pipe, and ageing effects of thermal treatment from coating process. The local bending strains measured via strain gauges and via optical strain measurements in the bending zone are evaluated for the tensile and compressive zone and discussed with respect to existing buckling models. The results of the full-scale test program confirmed that the weld connections of the pipe joints are capable of withstanding bending load. The effects of the girth weld and strip end weld during bending test are analyzed and discussed. The test results are extended by finite element simulations that widen the experimental parameter range.

Some components (elbows, pump casings and lateral connections) of the primary loop of French PWRs are made of static cast duplex stainless steels. This kind of steel may age even at relatively low temperatures (in the temperature range of PWR service conditions), depending on the material composition. An important consequence of this ageing process is the decrease in the ductility and fracture toughness of the material. It is feared that an embrittlement, associated with the occurrence of casting defects, may increase the risk of failure. In order to build the primary loops, these components are welded and the behaviour of the weld heat affected zone (HAZ) is not well known. So a specific program was launched on this topic, involving metallurgical studies, fracture mechanics tests, medium-scale experiments, and finite element analyses. This paper presents the main characteristics and results of an experiment conducted on a 6″ aged cast pipe. This pipe contained a machined notch in the heat affected zone of a butt-weld and was tested under four-point bending at 300°C. The chemical composition of the steel was chosen to obtain a fast thermal ageing and low fracture toughness properties. During the test, the defect initiated and grew subsequently by ductile tearing. The test showed that it was possible to obtain a significant amount of stable crack growth (about 4 mm) despite the low toughness properties of the aged material. A detailed fracture mechanics analysis, based on finite element calculations, was performed. These calculations fairly simulated the overall behaviour of the tested structure, gave a conservative prediction of the crack initiation pressure and well predicted the crack size associated with the maximum applied bending moment. These tests and their detailed analyses contribute to validate and justify the methodology used in the integrity assessment of in-service cast duplex stainless steel components.

The Finite Element Method (FEM) is a feasible tool to perform progressive collapse analyses of large structural systems. Despite enormous developments in finite element formulations and computer technologies the results of structural analyses should be validated against experimental results. In this paper the collapse behaviour of two identical box girder specimens is determined experimentally for the load case of pure longitudinal bending. The specimens are composed of stiffened plate panels and connected at either ends to a loading structure. Within a 4-point bending test a constant bending moment is applied to each specimen to determine the collapse behaviour even in the post-ultimate strength range. The results of the experimental determination of the ultimate strength are presented for the box girder specimens. To simulate the collapse behaviour a finite element model is used and validated against experimental results.

Within the framework of the FP7 European project STYLE, a large scale experiment has been performed at EDF on a cladded ferritic pipe. The objective of such an experiment was to investigate transferability of material properties from small specimens to large scale components. The large scale experiment involves applying 4-point bending under displacement control at room temperature to a clad ferritic steel pipe with an internal surface crack. The goal of the experiment is to initiate ductile crack growth and track the resulting stable crack growth until the surface flaw fails by producing a through-wall crack. The test specimen is representative from a surge line consisting of a clad ferritic pipe with an outer diameter of 420 mm, length of 520 mm, and base metal wall thickness of 31 mm, with an internal austenitic stainless steel cladding layer of thickness 5 mm. The base metal is a low alloy 20MnMoNi55 steel (corresponding to the specifications of an SA 508 Grade 3, Class 1 steel), and the necessary extensions are made of a high strength ferritic steel. A wide range of instrumentation was implemented to provide data for mock-up behavior understanding and detect the ductile tearing initiation during the test. The test has been conducted with full success on the EDF 4 point bending test facility. After the experiment, samples have been taken from the mock-up for full SEM fractographic examinations of the fracture surface for identification of failure modes. The present paper describes the large scale experiment and presents the main experimental results and data. A synthesis of SEM fractographic examinations is also presented, to better understand the rupture behavior during the test.

Abstract In the 1950’s Markl et al. conducted numerous fatigue test of welded piping components that were later used to develop the ASME B31 and other piping design codes. To analyze low cycle fatigue data, Markl proposed an extrapolation method to obtain the pseudo-elastic stress for fatigue data analysis. In this paper, this extrapolation method is revisited to figure out its underlining mechanism, application scope and limitation. Two sets of fatigue data representing 4 point bending and cantilever bending condition are analyzed to support the study. A structural strain method is then proposed as an improvement and generalization of Markl’s approach, which can correlate large amount weldment fatigue data in both low-cycle and high-cycle regime by defining an equivalent structural strain parameter.