bluuebunny/crossref_metadata_2025 huggingface dataset:
Second International Muskox Symposium/Deuxième symposium international sur le Boeuf musqué: Introduction
Authors: Flood Peter F.
Published: March 2009

Following the First International Muskox Symposium, held at the University of Alaska, Fairbanks, in 1983, it was agreed that a second symposium should be held in Canada in 1987 under the general guidance of a committee composed of A. S. Blix, L. Königsson, J. E. Rowell, H. Thing, and R. G. White. This symposium, the Second International Muskox Symposium, took place at the Western College of Veterinary Medicine, University of Saskatchewan, from 1 to 4 October 1987. It was attended by more than 70 people representing nine countries, including all of the circumpolar nations. The symposium covered all aspects of muskox biology ranging from the endocrinology of reproduction to paleontology. It also included a presentation on the takin (Budorcas taxicolor), regarded as the only close relative of the muskox. In all there were 32 papers, 24 posters, a workshop on the management of expanding muskox populations led by Dr. Graeme Caughley, and an informal evening discussion and display on the commercial use of muskoxen.The 14 papers included in this issue are those contributions to the symposium that represent completed original work that falls within the scope of the Canadian Journal of Zoology and is not in press elsewhere. Written accounts of other contributions to the symposium have been printed independently and are bound with reprints of the papers appearing here to form the Proceedings of the Second International Muskox Symposium. Copies of the proceedings may be purchased by writing to the above address.Grateful thanks are due to Janice Rowell, without whom muskoxen would never have become a focus of research in Saskatoon; there would then have been no reason to choose Saskatoon as the symposium site. John Blake, Ron Chaplin, Colleen Stevens, and Patti Wilk played an invaluable part in the local organization. Anne Gunn provided much essential advice and liaison with the Northwest Territories Wildlife Service, who were instrumental in organizing the workshop on expanding muskox populations. Financial support was generously provided by the Government of the Northwest Territories, the Northern Affairs Program of the Department of Indian Affairs and Northern Development, the Natural Sciences and Engineering Research Council of Canada, the City of Saskatoon, the University of Saskatchewan, and Gulf Oil Canada. A debt of gratitude is also owed to the Dean of the Western College of Veterinary Medicine, Dr. G. F. Hamilton, for his encouragement and for putting the facilities of the college at our disposal, and especially to Dr. John Tener who graciously acted as our honorary chairman and gave us a most stimulating opening address.
Guide to field classification by sex and age of the muskox
Authors: Olesen Carsten Riis , Thing Henning
Published: March 2009

Reliable data on sex–age class composition of muskox (Ovibos moschatus) herds are necessary prerequisites to any successful management initiative. The classification requires some training to be exact; this paper presents a photographic record and description of field characteristics of a total of eight different sex–age classes, thus enabling the observer to perform a correct herd segregation. Differentiation of muskoxen relies primarily on horn development and secondarily on body and pelage.
The structure and function of muskox preorbital glands
Authors: Gray David R. , Flood Peter F. , Rowell Janice E.
Published: March 2009

The preorbital gland of the muskox is a relatively large pear-shaped structure lying rostral to the eye between the skin and the lacrimal bone. It surrounds a narrow tubular invagination of the skin, which conveys the largely aqueous secretion to the surface of the face. This tube, which enters the gland at its rostrolateral extremity and runs caudodorsally, is partially filled with stiff hairs that arise from follicles in its wall. Most of the gland consists of tightly packed apocrine sweat glands, but large sebaceous glands are associated with the hair follicles of the central tube. The myoepithelium of the sweat glands is highly developed but the facial muscles overlying the gland are very thin and probably do not contribute significantly to the expulsion of secretion. Secretion is mechanically expressed when the animal rubs the area of the gland on something firm such as its own foreleg (gland rubbing) or a prominent object in the environment (rubbing). The gland is functional in both sexes throughout the year but is much larger in males. In the wild, scent marking and gland rubbing occur during aggressive encounters between individuals within a herd, between herds, and between muskoxen and other species. Gland rubbing in females and subadults is usually restricted to interspecific encounters but in males it occurs in most intense agonistic situations. Wild calves performed the self-marking behaviour as early as 1 week of age when play fighting. Captive muskoxen did not rub their preorbital gland on the foreleg but commonly rubbed it on objects. The authors believe that the principal function of the preorbital gland is to provide an olfactory component of the threat behaviour pattern.
Neophobia, aversion to open space, and ecological plasticity in Song and Swamp sparrows
Authors: Greenberg Russell
Published: March 2009

The Song Sparrow (Melospiza melodia) is a habitat generalist and successful colonist of habitats altered by man and of small islands. The Swamp Sparrow (Melospiza georgiana) is more restricted in its habitat distribution, occurring primarily in marsh or marsh-like habitats. In field experiments I examined the role of certain aversions in shaping the apparent difference in ecological plasticity found in these species. I tested for differences in aversion to feeding in the presence of novel objects and away from cover and found that such conditions greatly reduced the visitation rate of Swamp Sparrows but not Song Sparrows to feeding stations. I found no differences between the species in the degree to which feeding rate, visit length, or group size changed between areas with and without cover. Neither did I find a difference in feeding behavior or flight speed in the two species. I suggest that the increased hesitancy that Swamp Sparrows show for foraging away from cover or at novel objects reflects selection to reduce exploratory behavior away from preferred habitat types in this more stereotyped species.
Plasma levels of free and bound thyroid hormones during parr–smolt transformation in Atlantic salmon, Salmo salar L.
Authors: Boeuf Gilles , Uin Linda M. , Eales J. G.
Published: March 2009

To determine if the marked spring surges that occur in plasma L-thyroxine (T4) concentrations during parr–smolt transformation are due to changes in the properties or levels of thyroid hormone binding plasma proteins, plasma levels of total T4 (TT4) and 3,5,3′-triiodo-L-thyronine (TT3), indices of the percentage of T4 or T3 in the free form (%FT4 or %FT3), and indices of free T4 (FT4) and free T3 (FT3) levels were measured on a population of Atlantic salmon undergoing parr–smolt transformation under a natural temperature and photoperiod regime in Brittany, France. Gill Na+–K+ ATPase increased to a peak in mid-May, whereas TT4 exhibited two major peaks in late April and mid-June, with small seasonal change in TT3. Indices of the %FT4 and %FT3 changed negligibly, resulting in high correlations between TT4 and FT4 (r = 0.97) and TT3 and FT3 (r = 0.96). Thus the high TT4 peaks encountered during smoltification are not due to changes in properties of plasma T4 binding proteins and reflect approximately proportionate changes in the putative physiologically relevant FT4 level. The TT4 and FT4 peaks coincided with basal levels of TT3 and FT3, implying no systemic increase in T4 to T3 conversion and reinforcing the concept that T4 may exert a local tissue-specific role during parr–smolt transformation.
The efficacy of melanotic encapsulation as a defense against parasite-induced mortality in snowpool mosquitoes (Diptera: Culicidae) infected by mermithid nematodes
Authors: Blackmore Mark S.
Published: March 2009

The effects of host reactions to parasitism were studied in two species of mosquitoes (Diptera: Culicidae) infected with mermithid nematodes (Romanomermis sp.). No immune reactions were observed in Aedes impiger and virtually all (98.5%) infected larvae died before pupation. Mermithid infections of Aedes nevadensis resulted in high host mortalities (99.3% failed to pupate) when none of the parasites were encapsulated. Melanotic encapsulations of the nematodes were found in 67% of infected Aedes nevadensis, and larvae of this species that encapsulated all of their parasites had the same rate of survival as uninfected conspecifics. Survivorship of Aedes nevadensis larvae that encapsulated some but not all of their Romanomermis parasites was intermediate. Encapsulation also suppressed parasite-induced reductions in host size, and larvae that encapsulated all parasites were significantly larger than other Aedes nevadensis. This is the first quantitative demonstration of the efficacy of mosquito immune responses as defenses against mermithid parasites.
A method for estimating the ages of nestling Northern Harriers (Circus cyaneus)
Authors: Saunders Matthew B. , Hansen Gay L.
Published: March 2009

A model for predicting the age of nestling Northern Harriers (Circus cyaneus) is presented. The model requires measures of body mass, wing chord, and the presence or absence of tail feathers. Ninety-five percent confidence intervals of predicted ages are approximately ± 1.5 days, and the ages of chicks may be determined throughout the nestling period regardless of sex. This particular model was selected as it is highly accurate and employs variables that are easily obtained in the field.
The genus Anonyx (Crustacea, Amphipoda) in the North Pacific and Arctic oceans: Anonyx compactus group
Authors: Steele D. H.
Published: March 2009

The Anonyx compactus group is characterized by the morphology of the inner ramus of the second uropod, which is of normal length and depth but is completely constricted distally and bears a long spine at the constriction. This group comprises eight species of which three, Anonyx attenuatus, Anonyx stappersi, and Anonyx stebbingi, are newly described. Anonyx stappersi was identified as Chironesimus debruyni by L. Stappers and A. stebbingi as A. ampulloides by T. R. R. Stebbing. Seven of these species are known from the North Pacific region, and three from the North Atlantic region, but none has a circumpolar distribution.
Auditory localization in the northern saw-whet owl, Aegolius acadicus
Authors: Frost B. J. , Baldwin P. J. , Csizy M.
Published: March 2009

Although there are several anecdotal reports in the literature that northern saw-whet owls (Aegolius acadicus) have extremely accurate auditory localization abilities, there have been no attempts to quantify these observations. In this study we used the search coil technique to obtain precise measurements of the northern saw-whet owl's head orientation toward either cricket chirps or mouse squeaks presented through speakers at various azimuthal positions. The results indicate owls of this species can orient their heads toward sound sources with great accuracy in the azimuthal plane, yielding mean errors of <1.0°, but show a slight tendency to undershoot more peripherally located sounds. Vertical localization is somewhat less precise, but still very accurate. Subsequent studies will be aimed at elucidating the physiological and anatomical substrates of this extreme accuracy in auditory localization ability.
The role of selected environmental factors and sex ratio upon egg production in three-spine sticklebacks, Gasterosteus aculeatus
Authors: Bolduc Fabien , FitzGerald Gerard J.
Published: March 2009

We compared the fecundity of female sticklebacks (Gasterosteus aculeatus) breeding in salt marsh tide pools with that of fish breeding in the laboratory. Although total egg production was higher in the laboratory, there was no significant difference in clutch sizes between the two groups. In the field, physicochemical factors (water temperature, levels of dissolved oxygen, pH, and salinity) explained a statistically significant but small amount of the variation in the various measures of reproduction (daily egg production, total egg production, clutch size, interspawning interval) used. The results of a laboratory experiment concerning the effect of sex ratio upon female reproduction showed that this variable had little effect. The time spent on the breeding grounds appears to be the principal factor determining the seasonal fecundity of this species.
Two new species of Pycnophyes (Homalorhagida, Kinorhyncha) from the Canadian coast of the Beaufort Sea
Authors: Higgins R. P. , Korczynski R. E.
Published: March 2009

Two new homalorhagid kinorhynchs, Pycnophyes canadensis n.sp. and Pycnophyes borealis n.sp., are described from two localities near Tuktoyaktuk, Northwest Territories, Canada. Material collected in 1986 and 1987 from depths between 9.7 and 22.0 m in Tuktoyaktuk Harbour and nearby Mason Bay also included juvenile stages of a second homalorhagid genus, Kinorhynchus. These constitute the first kinorhynchs described from Canada, the first homalorhagid kinorhynchs from the Beaufort Sea, and the first Kinorhynchus from the Arctic.
Male-biased sex ratio in Argulus canadensis Wilson, 1916 (Crustacea: Branchiura) ectoparasitic on sticklebacks
Authors: Poulin Robert , FitzGerald Gerard J.
Published: March 2009

Females of the ectoparasitic crustacean Argulus canadensis must leave their fish hosts at least temporarily to deposit their eggs on the substrate. To test the hypothesis that this difference in reproductive behaviour between the two sexes could result in male-biased sex ratios on their stickleback hosts, we sampled sticklebacks in tide pools of a Quebec salt marsh from early July to early September 1986. During this period, fish harboured significantly more male than female A. canadensis. Laboratory experiments were done to test two alternative hypotheses offered to explain this biased sex ratio. The first hypothesis was that male A. canadensis were more successful than females in attacking their stickleback hosts; however, we found no differences in attack success on their hosts between the two parasite sexes. The second hypothesis was that sticklebacks ate more female than male A. canadensis. Although males were less vulnerable to fish predation than females, the difference was not significant. We conclude that sexual differences in reproductive behaviour, i.e., egg deposition behaviour of females, can account for the male-biased sex ratio of A. canadensis on sticklebacks.
Variation in developmental biology of sockeye salmon (Oncorhynchus nerka) and chinook salmon (O. tshawytscha) in British Columbia
Authors: Beacham Terry D. , Murray Clyde B.
Published: March 2009

Embryos and alevins of coastal-spawning and interior-spawning sockeye (Oncorhynchus nerka) and chinook (O. tshawytscha) salmon stocks in British Columbia were incubated under controlled water temperatures of 2, 4, 8, 12, and 15 °C. At low incubation temperatures, interior-spawning stocks of both species had smaller eggs and higher embryo survival rates than did coastal-spawning stocks. Interior-spawning stocks had faster developmental rates to alevin hatching and fry emergence than did coastal-spawning stocks. Interior-spawning stocks had proportionately larger alevins or fry at 2 °C (for sockeye salmon) or 4 °C (for chinook salmon) relative to their performance at 8 °C than did coastal-spawning stocks. Red-fleshed chinook salmon had higher embryo survival rates at 15 °C than did white-fleshed chinook salmon, as well as an indication of proportionately larger alevins or fry relative to the performance at lower incubation temperatures. Differences in developmental biology of interior- and coastal-spawning stocks may reflect adaptation to the thermal conditions experienced during development.
Ontogeny of the Weberian apparatus of Clarias gariepinus (Pisces, Siluriformes)
Authors: Radermaker Francis , Surlemont Chantal , Sanna Patricio , Chardon Michel , Vandewalle Pierre
Published: March 2009

The Weberian apparatus of Clarias gariepinus is described at nine stages from hatching to 27 days old. Homologies are discussed. The claustrum, scaphium, tripus, and os suspensor appear to form one single piece. The scaphium is a basidorsal of the first vertebra, the tripus is a basiventral of the third vertebra, and the os suspensor is a basiventral of the fourth vertebra. At 9 days old the five anterior vertebrae are distinct and free; the complex vertebra is formed later and is composed at least of centra 3, 4, and 5. The intercalarium may not be a transformed second basidorsal, but an anterior part of the tripus.
Overwintering strategy of the stem-gall inducer Diplolepis spinosa (Hymenoptera: Cynipidae) in central Ontario
Authors: Rickards Julian C. , Shorthouse Joseph D.
Published: March 2009

Diplolepis spinosa overwinters as prepupae in large stem galls on rose bushes. The galls are often above the level of the snow, thus exposing the insects within to unabated winter temperatures. Diplolepis spinosa is a freezing-intolerant insect, consistently maintaining its supercooling points below ambient temperatures. It maintained an average supercooling point value of −37.9 ± 5.7 °C between December 29, 1986, and April 8, 1987, at Sudbury, Ontario, during which time the lowest recorded temperature was −31.6 °C. Its low supercooling points were primarily attained by the synthesis and accumulation of glycerol as an antifreeze agent. Glycerol concentrations began rising on October 27, peaked at a concentration of 1032 μmol/g wet weight on December 29 and fell after March 6. The trigger temperature for the initiation of glycerol synthesis was thought to be between 5 and 0 °C. Glycogen accounted for 87% of the glycerol accumulated. A further 3% of the glycerol pool may be accounted for by the contribution of acyl glyceride glycerol liberated by the catabolism of lipid glycerides. It is also suggested that D. spinosa avoids external ice inoculation by consuming all moisture-laden nutritive cells down to the sclerenchyma layer, and avoids internal ice inoculation by defecating before winter.
Impact of parasitism by larval Limnochares aquatica (Acari: Hydrachnidia; Limnocharidae) on juvenile Gerris comatus, Gerris alacris, and Gerris buenoi (Insecta: Hemiptera; Gerridae)
Authors: Smith Bruce P.
Published: March 2009

Laboratory-reared first-instar juvenile Gerris comatus Drake &Hottes, Gerris alacris Hussey, and Gerris buenoi Kirkaldy were exposed to larval Limnochares aquatica (L.). Development and mortality of parasitized juvenile water striders were monitored and compared with those of unparasitized insects. Duration of infestation was from 6 to 13 days during which surviving hosts moulted several times, with engorging larvae transferring to the teneral host during the moulting process. Most mites dropped off the host during the host's second instar, and all mites were off the host by the host's fourth instar. Parasitism by larval mites significantly increased mortality, duration of instars, and variance in age at first moult for parasitized water striders. Mortality and duration of first instars were directly correlated with number of mites per host. Parasite-induced mortality was not evident until 2 days after attachment of mites, and almost all mortality occurred within the host's first instar. Gerris comatus and G. alacris apparently did not differ in response to parasitism; however, G. buenoi showed greater mortality than the other gerrid species when carrying comparable numbers of mites. The effects of parasitism on juvenile water striders within natural populations are predicted to be severe, and would reduce recruitment while also increasing variation in age structure.
Sexual reproduction and larval development of Rhaphidrilus nemasoma Monticelli, 1910 (Polychaeta: Ctenodrilidae)
Authors: Qian Pei-Yuan , Chia Fu-Shiang
Published: March 2009

Adult specimens and egg masses of Rhaphidrilus nemasoma were collected in the low intertidal zone from Execution Rock, Bamfield, Vancouver Island, British Columbia, in June of 1986. Each egg mass contained about 1000 eggs. The eggs were green, spherical, and measured 125–145 μm in diameter. Larval development took place within the egg mass until the three-or four-setiger stage, at which time they emerged from the egg mass. Newly emerged larvae crawled on the bottom of the culture beakers and fed on benthic diatoms. Metamorphosis took place soon after emergence and was completed within 2 weeks. Paddle cilia were observed at the early trochophore stage, and their possible function, and the extremely high fecundity of this polychaete, are discussed.
Nematode parasites of bark beetles (Scolytidae) in southern Manitoba, with descriptions of three new species of Sulphuretylenchus Rühm (Nematoda: Allantonematidae)
Authors: Tomalak M. , Welch H. E. , Galloway T. D.
Published: March 2009

Thirty-one species of bark beetles were collected from nine genera of host plants at 29 locations in southern Manitoba during 1980–1983. Of these bark beetle species, 21 were infected by as many as 56 species of nematodes, based on examination of adult and juvenile stages. There were 30 species of allantonematids, all recovered from the hosts' haemocoel. Fourteen rhabditid species were recovered from the alimentary tract of 15 host species. Twelve aphelenchoids were found in both the haemocoel (of 10 host species) and the Malpighian tubules (of 2 host species). Three new species of Sulphuretylenchus are described. Sulphuretylenchus pseudoundulatus sp.nov. parasitized Polygraphus rufipennis (Kirby) collected in the Whiteshell Provincial Forest. Sulphuretylenchus nopimingi sp.nov. parasitized Pityokteines sparsus (LeConte) collected in Nopiming Provincial Park. Sulphuretylenchus posteruteri sp.nov. parasitized Ips perroti Swaine in the Belair Provincial Forest.
Sex ratio of loggerhead sea turtles hatching on a Florida beach
Authors: Mrosovsky N. , Provancha Jane
Published: March 2009

Hatchling loggerhead sea turtles (Caretta caretta) were collected over the summer nesting season from a major rookery at Cape Canaveral, Florida, in 1986. Sex was assessed using histological criteria. From data on the distribution of nests over the season, we estimated that in 1986, > 93% of the hatchlings produced on this beach were females. This huge bias toward females is consistent with sand temperatures at the depth of turtle nests; for most of the season these temperatures were above the pivotal level for loggerhead turtles. The results suggest that in the future, turtles in this area will encounter difficulty in overcoming the feminizing effect of global warming and that biologists should pay more attention to the beaches at the northern end of the loggerhead's nesting range.
A new prairie dog, Cynomys churcherii, from the Late Pleistocene of southern Alberta
Authors: Burns James A. , McGillivray W. Bruce
Published: March 2009

Excavation of fossil burrows in the Hand Hills, about 30 km northeast of Drumheller, Alberta, has produced over 3000 skeletal remains, including major portions of nine associated skeletons of a species of prairie dog (Cynomys) dating from 22 000 to 33 000 BP. All lower third molars possess the stylid feature characteristic of white-tailed prairie dogs (subgenus Leucocrossuromys). Similarly, the conformation of the zygomatic arch is peculiar to whitetails. Morphometric analyses based on 10 characters from 9 skulls and 6 characters from 22 mandibles show that the fossil population is significantly different from extant C. ludovicianus, C. leucurus, and C. gunnisoni. Skull length, a good measure of overall size, is significantly greater in the fossil population than in any Recent Cynomys species. The fossil localities are not montane sites typical of extant whitetail populations, and the fossil mammal community differs little from the modern assemblage expected in an aspen groveland in Alberta. The morphological distinctiveness of the fossils, plus the uncharacteristic (for whitetails) habitat association, suggest the erection of a new taxon, Cynomys churcherii n.sp.
Effect of corpus cardiacum, ventral ganglia, and proline on absorbate composition and fluid transport by locust hindgut
Authors: Lechleitner R. A. , Phillips J. E.
Published: March 2009

Extracts of corpus cardiacum and fifth ventral ganglion stimulated transport of K+, Cl−, and fluid across everted rectal sacs exposed luminally to either high-NaCl or high-KCl saline, whereas there was little or no increase in Na+ absorption. These results contrast with the large increase in Na+ absorption across the ileum caused by the same extracts. Moreover, proline transport across the two hindgut segments differs: a large net proline flux occurs across the rectum but not the ileum under similar conditions. Not surprisingly, therefore, increasing proline concentrations in the bathing saline had no effect on ileal fluid transport. However, changing the external proline concentration from 1 to 80 mM caused a substantial increase in fluid transport across everted rectal sacs, and this persisted when external Na+, K+, and Cl− were absent, and when the osmolarity of the luminal saline was increased.
New species of haemoproteids from the avian families Paridae and Sittidae
Authors: Bennett Gordon F.
Published: March 2009

A unique discoid haemoproteid from the tufted titmouse, Parus bicolor L., is described as Haemoproteus parus. A halteridial haemoproteid from the white-breasted nuthatch, Sitta carolinensis Latham is described as Haemoproteus sittae.
Development of Skrjabinocerca prima (Nematoda: Acuarioidea) in Hyalella azteca (Amphipoda) and Recurvirostra americana (Aves: Charadriiformes), with comments on its precocity
Authors: Bartlett Cheryl M. , Anderson R. C. , Wong P. L.
Published: March 2009

Skrjabinocerca prima Shikhobalova, 1930 developed to the infective third stage in 40 days in Hyalella azteca (Saussure) maintained at 21 °C. Infective larvae occur free in the haemocoel and may impede the amphipod's motility because they lie semirigid and parallel to the longitudinal axis in the posterior abdominal segments. The genital primordium in infective-stage males was 200–520 μm long (averaging 19% of body length) and in females 860–1175 μm (averaging 42% of body length). This is unusually large, even compared with other acuarioids in which precocial development of the third-stage genital primordium is known. Additional evidence is provided for the hypothesis that precocity in nematodes is related to rapid maturity in the final host; in experimentally infected American Avocets (Recurvirostra americana Gmelin), moulting third-stage S. prima were found 2 days postinfection and moulting fourth stage at 4 days. Female nematodes contained embryonated eggs at 7 days; eggs in females became larvated between 10 and 18 days postinfection. In birds, the heads of larval and adult nematodes were attached to the mucosa of the buccal cavity or the upper third of the oesophagus, and adults provoked chronic inflammation in the form of yellow plaques. Worms are able to detach and reattach. Third-stage S. prima given to Marbled Godwits (Limosa fedoa (L.)) and Western Willets (Catoptrophorus semipalmatus inornatus (Brewster)) developed to maturity; the parasite has not been reported from the former species in the wild.
A new species of Orbitacolax (Copepoda: Bomololochidae) and redescriptions of two additional species
Authors: Cressey Roger , Cressey Hillary Boyle
Published: March 2009

A new species, Orbitacolax williamsi, is described from Okinawa, Japan. It differs from the known species of the genus by the presence of a very long seta at the tip of the fourth leg. Orbitacolax hapalogenyos Yamaguti and Yamasu is reported and redescribed from the gulf of Mexico, Caribbean Sea, and Brazil. Orbitacolax analogus Vervoort is redescribed and O. oniscoides Vervoort is placed in synonomy with O. analogus.
DYNAMIC CRUSHING SIMULATION OF METALLIC FOAMS WITH RESPECT TO DEFORMATION AND ENERGY ABSORPTION
Authors: ZHANG Y. F. , ZHAO L. M.
Published: March 2009

In this paper, a two-dimensional nonlinear elastic-plastic mass-spring-damper-rod element model is employed to simulate the crush behavior of metallic foams. The density heterogeneity and pore fluid of metallic foams are considered. The metallic foams are compressed by applying a planar pulse loading or by giving a deformation rate. Several numerical results show the deformation patterns and the energy absorption regime of metallic foams under crush loading. The influence of heterogeneous density, cell fluid, loading intensity, deformation rate on the deformation and the energy absorption of metallic foams is assessed.
A FULL CONSTITUTIVE RELATION OF SILICON–STEEL SHEET WITH ANISOTROPY CONSIDERED
Authors: BYON S.M. , YOO U.K. , LEE Y.
Published: March 2009

We present a full constitutive relation of silicon steel which can describe the anisotropy effect as well. Using a pilot rolling machine, initial silicon strip with thickness of 2.5mm is rolled into sheet with several thicknesses as reduction ratio increases from 10% to 90%. To examine the effect of anisotropy on the stress-strain behavior, the specimen was cut out from the sheet so that the direction of specimen and sheet is 0°, 30°, 45°, 60° and 90°, respectively. A series of tensile test are then performed with the specimens. The stress-strain curves computed from the proposed constitutive relation are compared with the experimental data. Results show that the predicted curves are in overall in a good agreement with measured ones. The work hardening and unstable softening behaviors of silicon steel during rolling are predicted by the proposed full constitutive relation.
CREEP ANALYSIS FOR A WIDE STRESS RANGE BASED ON STRESS RELAXATION EXPERIMENTS
Authors: ALTENBACH HOLM , NAUMENKO KONSTANTIN , GORASH YEVGEN
Published: March 2009

Many materials exhibit a stress range dependent creep behavior. The power-law creep observed for a certain stress range changes to the viscous type creep if the stress value decreases. Recently published experimental data for advanced heat resistant steels indicates that the high creep exponent (in the range 5-12 for the power-law behavior) may decrease to the low value of approximately 1 within the stress range relevant for engineering structures. The aim of this paper is to confirm the stress range dependence of creep behavior based on the experimental data of stress relaxation. An extended constitutive model for the minimum creep rate is introduced to consider both the linear and the power law creep ranges. To take into account the primary creep behavior a strain hardening function is introduced. The material constants are identified for published experimental data of creep and relaxation tests for a 12% Cr steel bolting material at 500°C. The data for the minimum creep rate are well-defined only for moderate and high stress levels. To reconstruct creep rates for the low stress range the data of the stress relaxation test are applied. The results show a gradual decrease of the creep exponent with the decreasing stress level. Furthermore, they illustrate that the proposed constitutive model well describes the creep rates for a wide stress range.
AN IMPROVED ANALYTICAL CONSTITUTIVE RELATION FOR NORMAL WEIGHT HIGH-STRENGTH CONCRETE
Authors: LU Z. H. , ZHAO Y. G.
Published: March 2009

In this paper, some available analytical models for the complete stress-strain curve for high-strength concrete (HSC) under uniaxial compression are examined and compared with experimental curves published in the literature. Based on these findings, a new analytical constitutive relation is proposed to generate the complete stress-strain curves for normal weight concrete subjected to uniaxial compression with a strength range of 60-120MPa. To demonstrate the validity of the model, comparisons are made with published experimental data for uniaxial compressive tests on high-strength concrete specimens. The present model is shown to give a quite good representation of mean behavior of the actual stress-strain response.
STUDY ON THE FRACTURE BEHAVIOR OF W-NI-FE HEAVY ALLOYS
Authors: SONG WEIDONG , NING JIANGUO , LIU HAIYAN
Published: March 2009

The fracture behaviors of tungsten alloys 91 W -6.3 Ni -2.7 Fe were investigated by tensile tests and numerical simulations. Firstly, tensile tests were conducted on the S-570 SEM with an in-situ tensile stage. With this system, the process of deformation, damage and evolution in micro-area can be tracked and recorded, and at the same time, the load-strain curve can be drawn. Secondly, the 2D finite element model of a unit cell for the tungsten alloys was established by using finite element program. By copying the unit cell model, the macro-model of the alloys was given. Dozen of cases were performed to simulate the fracture behaviors of tungsten alloys. Thirdly, the random model of the alloys was established. The fracture patterns of the alloys were investigated by the model. The interface between the tungsten particle and the matrix was explored in details. The effect of interface strength on the fracture patterns of the alloys was taken into account. A good agreement was achieved between the experimental results and the numerical predictions.
EFFECT OF VARIOUS HEAT TREATMENT PROCESSES ON FATIGUE BEHAVIOR OF TOOL STEEL FOR COLD FORGING DIE
Authors: JIN S. U. , KIM S. S. , LEE Y. S. , KWON Y. N. , LEE J. H.
Published: March 2009

Effects of various heat treatment processes, including "Q/T (quenching and tempering)", "Q/CT/T (Quenching, cryogenic treatment and tempering)", "Q/T (quenching and tempering) + Ti -nitriding" and "Q/CT/T (Cryogenic treatment and tempering) + Ti -nitriding", on S - N fatigue behavior of AISI D2 tool steel were investigated. The optical micrographs and Vicker's hardness values at near surface and core area were examined for each specimen. Uniaxial fatigue tests were performed by using an electro-magnetic resonance fatigue testing machine at a frequency of 80 Hz and an R ratio of -1. The overall resistance to fatigue tends to decrease significantly with Ti -nitriding treatment compared to those for the general Q/T and Q/CT/T specimens. The reduced resistance to fatigue with Ti -nitriding is discussed based on the microstructural and fractographic analyses.
LOAD CARRYING CAPACITY OF CORRODED REINFORCED CONCRETE BEAMS SUBJECTED TO REPEATED LOAD
Authors: FANG CONGQI , YI MEIYING , CHENG SHUJIAN
Published: March 2009

Load carry capacity of corroded reinforced concrete beams under repeated load was investigated experimentally. A total of fifteen test samples, including three non-corrosion and twelve corroded reinforced concrete (RC) beams, were experimentally evaluated for midspan deflection, cracking of concrete, and failing modes under repeated loading. Beams of different corrosion percentage were tested for the effect of steel corrosion and repeated loading. For corroded RC beams width and spacing of cracks increased significantly with steel corrosion. Before the yielding of the reinforcement steel, midspan deflection for beams of lower corrosion percentage was less than that of non-corrosion beams. However, as the reinforcement steel yielded, the midspan deflection of corroded beams was significantly larger than those of non-corrosion beams, and this tended to increase with corrosion percentage. As the reinforcing steel was severely corroded, the beam showed a mechanical characteristic similar to a camber, where arch action was more obvious.
A MODEL FOR GALLING BEHAVIOR IN FORMING OF HIGH STRENGTH STEEL UNDER TENSION-BENDING
Authors: HOU Y.K. , ZHANG W.G. , YU Z.Q. , LI S.H.
Published: March 2009

Galling is a known failure mechanism in sheet metal forming (SMF), especially in the forming of high strength steels. It results in increased cost of die maintenance and scrap rate of products. In this study, U-channel forming tests were conducted to study the galling behavior under the condition of tension-bending. The effects of tool surface characteristics (hardness and surface roughness) and process parameters (blank holder force and sliding distance of the contact surfaces) on galling were investigated. Experimental results indicate that galling tendency can be reduced through hardening and polishing of the forming tool and galling becomes more severe with increasing blank holder force and sliding distance in SMF. A numerical model between the galling and these factors was established through non-linear curve fitting of the large amount of experimental data.
DYNAMIC FAILURE OF A SPOT WELD IN LAP–SHEAR TESTS UNDER COMBINED LOADING CONDITIONS
Authors: SONG J. H. , HA J. W. , HUH H. , LIM J. H. , PARK S. H.
Published: March 2009

This paper is concerned with the evaluation of the dynamic failure load in the lap-shear tests of a spot weld. Dynamic lap-shear tests of a spot weld in SPRC340R were conducted with different tensile speeds ranging from 5×10-5 m/sec to 5.0 m/sec. Dynamic effects on the failure load of a spot weld are examined based on the experimental data. Experimental results indicate that failure strength increases with increasing loading rates. Finite element analyses of dynamic lap-shear tests were also performed considering the failure of a spot weld. A spot weld is modeled with a beam element and dynamic failure model is utilized in order to describe the failure of a spot weld in the simulation. The failure loads obtained from the analyses are compared to those from the lap-shear tests. The comparison shows that the failure loads obtained from the analyses are close in consistence with those obtained from the experiments.
NUMERICAL SIMULATION OF DYNAMIC FAILURE FOR ALUMINA CERAMIC
Authors: HUILAN REN , JIANGUO NING
Published: March 2009

The plate impact experiments have been conducted to investigate the dynamic behavior of alumina. Based on the experimental observations, the three-dimensional finite element models of flyer and alumina target are established by adopting ANSYS/LS-DYNA, several cases were performed to investigate the fracture behavior of alumina target under impact loading. By analyzing the fracture mechanism and damage process of the alumina target, it is concluded that the nucleation and growth of great number of radial and axial cracks and circumferential cracks play a dominant role in the fracture behavior of alumina target. The stress histories of alumina target are simulated. By the comparison of experimental results with the numerical predictions, a good correlation is obtained.
ANALYSIS OF DYNAMIC STRESS-STRAIN RELATIONSHIP OF LOESS
Authors: LIAO HONGJIAN , ZHANG ZHIGANG , NING CHUNMING , LIU JIAN , SONG LI
Published: March 2009

This paper aims to study dynamic properties of loess. This study is helpful to the subject on how to avoid or decrease the seismic disasters on loess ground. Dynamic triaxial tests are carried out with saturated remoulded soil samples taken form loess sites in Xi'an, China. Dynamic stress and strain relationship as well as the rule of the accumulated residual strain are obtained from the test results. Linear relationship between accumulated residual strain and vibration circle under constant amplitude circular loading is presented. A hypothesis about the accumulated residual strain is proposed. 1D dynamic constitutive relationship model which can well describe the real relationship between dynamic stress and strain under irregular dynamic loading is established. Numerical program with this model is developed and an example is tested. Numerical results of hysteresis loop, accumulated residual strain, amplitude of dynamic stress and damping ratio show good agreement with test results. It is indicated that the hypothesis of accumulated residual strain and the 1D dynamic constitutive relationship model can accurately simulate the dynamic triaxial tests of saturated remoulded loess.
TRIMMING LINE DESIGN USING AN INCREMENTAL DEVELOPMENT METHOD AND A FINITE ELEMENT INVERSE METHOD
Authors: SONG YOUN-JOON , PARK CHUN-DAL , HAHN YOUNG-HO , CHUNG WAN-JIN
Published: March 2009

In automobile panel manufacturing, the design of a feasible trimming line is crucial in obtaining an accurate edge profile after flanging. In this study, an effective method which combines the robust incremental development method and finite element inverse method is presented. The finite element inverse method is used to analyze the flanging process. In using the finite element inverse method, the main obstacle is the generation of the initial guess. An improved incremental development method is presented to handle badly-shaped element, various element sizes, and undercut parts. This method incrementally develops a 3D triangular mesh onto the drawing tool surface by layer-wise development and smoothing technique. The effectiveness of this method is verified by two numerical examples.
DYNAMIC SIMULATION OF THE TAILING PROCESS IN HOT FINISHING MILL
Authors: KIM SHINIL , LU CHENG , DU XIAOZHONG , TIEU ANH KIET
Published: March 2009

In this paper an explicit dynamic finite element method model has been developed to investigate the strip deformation behavior between two adjacent stands in hot finishing mill. The effect of the roll speed ratio of second stand to first stand on tension and the tailing behavior of the strip has been discussed in details. It has been found that the strip accumulation occurs if the roll speed ratio is small. The tensile stress increases with the roll speed ratio. During the tailing process the accumulated strip caused by the small roll speed ratios knocks onto the roll, while the swing of the strip tail occurs for the large roll speed ratios and it strikes the roll as well. Both tailing phenomena will result in the strip tail pincher or roll damage in the real operation.
NUMERICAL OPTIMIZATION OF SHEET METAL FORMING PROCESS USING NEW FRACTURE CRITERION
Authors: HIRAHARA A. , HINO R. , YOSHIDA F. , TOROPOV V. V.
Published: March 2009

A numerical optimization system for sheet metal forming process has been developed based on a combination of response-surface-based optimization strategy with finite element simulation. The most important feature of the optimization system is introduction of a new fracture criterion to predict fracture limit under non-proportional deformation. In addition, a sheet-edge fracture criterion is also introduced to predict fracture limit under stretch-flanging deformation. The numerical optimization system is developed using the fracture criteria as accurate fracture constraints to avoid sheet breakage. The developed optimization system is applied to the optimum blank design for a square-cup deep drawing process of perforated blank. The optimum blank design, which minimizes the amount of material and avoids the sheet fracture, is obtained successfully. The effect of definition of fracture constraints on optimization calculation is also discussed.
RIGID-PLASTIC SEISMIC DESIGN OF REINFORCED CONCRETE SHEAR WALL
Authors: FAN CHANG LIN , ZHANG SHAN YUAN
Published: March 2009

Basing the displacement-capacity design method and capacity spectrum method, a new rigid-plastic seismic design procedure is proposed to describe the behavior of shear wall structure under strong earthquakes. Firstly the concept of rigid-plastic hinge is used to choose a collapse mechanism of shear wall, then according to the dynamic performance criterion the yield load of structure is determined through rigid-plastic response spectrum. This procedure is used in 11-story reinforced structure shear wall design, the results of comparison with refined Non-Linear Time-History Analysis showing good agreement.
NUMERICAL STUDY ON THE SHAPED CHARGES
Authors: MA TIANBAO , WANG CHENG , NING JIANGUO
Published: March 2009

This paper developed a hydro-elasto-plastic method to describe the mechanical behavior of the metal material under explosion load. Based on this method, the EXPLOSION-2D hydrocode was developed, and the shaped charges with steel liner and copper liner were numerically simulated, respectively. The simulation results agree well with experimental ones, which show that the proposed method is efficient for engineering design.
NUMERICAL SIMULATION OF DEEP DRAWING PROCESS OF ALUMINUM ALLOY SHEET USING CRYSTAL PLASTICITY
Authors: SHIM JUNG GIL , KEUM YOUNG TAG
Published: March 2009

In this study, the FEM material model based on the crystal plasticity is introduced for the numerical simulation of deep drawing process of A5052 aluminum alloy sheet. For calculating the deformation and stress in a crystal of aluminum alloy sheet, Taylor's model is employed. To find the texture evolution, the crystallographic orientation is updated by computing the crystal lattice rotation. In order to verify the crystal plasticity-based FEM material model, the strain distribution and the draw-in amount are compared with experimental measurements. The crystal FEM strains agree well with measured strains. The comparison of draw-in amount shows less 1.96% discrepancy. Texture evolution depends on the initial texture.
CHARACTERIZATION OF BAINITIC MICROSTRUCUTRES IN LOW CARBON HSLA STEELS
Authors: KANG JU SEOK , PARK CHAN GYUNG
Published: March 2009

The austenite phase of low carbon steels can be transformed to various bainitic microstructures such as granular bainite, acicular ferrite and bainitic ferrite during continuous cooling process. In the present study site-specific transmission electron microscope (TEM) specimens were prepared by using focused ion beam (FIB) to identify the bainitic microstructure in low carbon high strength low alloy (HSLA) steels clearly.

Granular bainite was composed of fine subgrains and 2nd phase constituents like M/A or pearlite located at grain and/or subgrain boundaries. Acicular ferrite was identified as an aggregate of randomly orientated needle-shaped grains. The high angle relations among acicular ferrite grains were thought to be caused by intra-granular nucleation, which could be occur under the high cooling rate condition. Bainitic ferrite revealed uniform and parallel lath structure within the packet. In some case, however, the parallel lathes showed high angle relations due to packet overlapping during grow of bainitic ferrite, resulting in high toughness properties in bainitic ferrite based steels.
EFFECT OF HIGH TEMPERATURE DEFORMATION ON THE LOW THERMAL EXPANSION BEHAVIOR OFFE-29%NI-17%COALLOY
Authors: LEE K. A. , NAMKUNG J. , KIM M. C.
Published: March 2009

The effect of high temperature deformation on the low thermal expansion property of Fe -29 Ni -17 Co alloy was investigated in the compressive temperature range of 900~1300°C at a strain rate range of 25 ~ 0.01 sec.-1. The thermal expansion coefficient (α30~400) generally increased with increasing compressive temperature. In particular, α30~400increased remarkably as the strain rate decreased at temperatures above 1100°C. Note, however, that α30~400at low compressive temperatures (900°C and 1000°C) increased abnormally at high strain rates. Based on the investigation of various possibilities of change in low thermal expansion behavior, the experimental results indicated that both the appearance of the α phase and evolution of grain size due to hot compression clearly influenced the low thermal expansion behavior of this invar-type alloy. The correlation between the microstructural cause and invar phenomena and theoretical explanation for the low thermal expansion behavior of Fe -29% Ni -17% Co were also suggested.