bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationships Between the Modulus of Elasticity and Tensile Strength for Pharmaceutical Drugs and Excipients
Authors: Roberts R J , Rowe R C
Published: October 2002

The relationship between the modulus of elasticity and tensile strength for a variety of pharmaceutical drugs and excipients has been explored as a means of generating algorithms for use in computer simulations and expert systems.

From literature data two equations have been developed to enable the formulator, from knowledge of one property, to predict the other with a reasonable degree of accuracy.

Such relationships are invaluable for use in computer simulation programs or formulation expert systems, enabling formulators to screen potential formulations quickly without the need for extensive experimental work.
A Dissolution Test for a Pressure-controlled Colon Delivery Capsule: Rotating Beads Method
Authors: Yukako Yoshikawa , Hu Zhaopeng , Kimura GO , Murakami Masahiro , Yoshikawa Hiroshi , Takada Kanji
Published: October 2002

The rotating beads method is a new in-vitro dissolution test proposed for drugs formulated as pressure-controlled colon delivery capsules (PCDCs).

The apparatus consisted of a glass vessel (500 mL) containing 4-mm (i.d.) glass beads (5000, 10000 or 15000) and dissolution medium (0.067 M phosphate buffer, pH 7; 25, 50 or 100 mL) containing polyvinyl alcohol (PVA; 5, 10 or 20 w/v%) to simulate the viscosity of the colon. The vessel was rotated at 5, 10 or 25 rev min−1 and the temperature was maintained at 37°C. Fluorescein was used as a model drug to explore the optimized conditions under which differences in the drug dissolution rate are detected between colon delivery systems. Fluorescein was formulated in four types of colon delivery systems. One was a tablet coated with an enteric polymer, Eudragit S-100, and the other three were PCDCs prepared with different thicknesses of ethylcellulose coating membrane (type I, II, III).

The dissolution behaviour of fluorescein from the PCDC formulation was significantly different from that of the Eudragit S-100-coated tablets, when the dissolution conditions were as follows: rotation speed, 10 rev min−1; bead number, 10000; dissolution medium, 50 mL with 10% PVA. This dissolution method was applied to acetaminophen sustained-release tablets and two other drugs having low solubility in the colon, tegafur and 5-aminosalicylic acid. Similarly, significant differences in the dissolution rates of drugs from the PCDC formulation and the enteric tablet were detected. There was good correlation between the in-vitro dissolution rates and in-vivo absorption rates using T50 (the time for half of the amount of drug to be released from the preparation) and Cmax/Tmax (enteric tablet) or Cmax/(Tmax-Ti) (PCDC), where Ti is the first appearance time in the systemic circulation.

The rotating beads method is a valuable technique for evaluating the dissolution rate of drugs formulated in PCDC.
Studies on the Co-encapsulation, Release and Integrity of Two Subunit Antigens: rV and rF1 from Yersinia pestis
Authors: Spiers Ian D , Alpar H Oya , Eyles Jim E , Bozkir Asuman , Miller Julie , Williamson E Diane
Published: October 2002

In the development of combination or multiple sub-unit vaccines, determination of the encapsulation, release and integrity of two or more proteins co-encapsulated within microspheres is an important issue. A new extraction method, which exhibits excellent protein recovery, has been developed which enables samples to be used for sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and subsequent measurement of individual antigens encapsulated within microspheres. Using the new method, the protein loading of poly-(L-lactide) microspheres co-encapsulating two plague sub-unit antigens was found to be 1.22% (w/w) for recombinant V antigen (rV) and 1.24% (w/w) for recombinant F1 (rF1) by SDS-PAGE. The total protein loading was 2.49% (w/w) by bicinchoninic acid assay. The individual release of the two subunit antigens from the co-encapsulated microspheres was determined by SDS-PAGE analysis and rF1 was found to have a higher burst release than rV. The integrity and immunological activity of both rF1 and rV antigens was shown to be unaffected by the microencapsulation process.

This study shows that encapsulation of more than one antigen within poly-(L-lactide) microspheres is a viable method for the delivery of intact proteins.
Renal Handling of Iodobenzoates in Rats
Authors: Laznicek Milan , Laznickova Alice
Published: October 2002

Renal elimination pathways of three positional isomers of iodobenzoic acid (2-iodobenzo-ate, 3-iodobenzoate and 4-iodobenzoate radiolabelled with 125I) were compared using the perfused rat kidney in-situ.

All agents were eliminated both in a parent form (involving all renal elimination mechanisms i.e. glomerular filtration, tubular secretion, and tubular reabsorption) and also metabolized to a large extent in the kidney. After 3-iodobenzoate and 4-iodobenzoate administration, the major fractions of radioactivity found in urine were in the form of their metabolites, whereas 2-iodobenzoate was eliminated into urine mostly as the parent compound. Proportions of the individual metabolites in the urine of the perfused rat kidney were similar to those in intact rats for all agents.

The results suggest that the kidney is the major organ for both the excretion and metabolism of iodobenzoates in rats. The principal renal metabolic reaction for all compounds under study was conjugation with glycine to produce the corresponding hippuric acid derivatives.
Gastrointestinal First-pass Effect of YJA-20379-8, a New Reversible Proton Pump Inhibitor, in Rats
Authors: Kim Jonghan , Kim Eun J , Han Kye S , Chang Man S , Lee Myung G
Published: October 2002

Since low bioavailability of YJA-20379-8 (3-butyryl-4-[5-R-(+)-methylbenzylamino]-8-ethoxy-1, 7-naphthyridine), a new reversible proton pump inhibitor, has been reported after oral administration of the drug to rats, the first-pass organ of the drug was investigated in rats. YJA-20379-8, 50 mg kg−1, was infused over 1 min via the jugular vein (n = 5) or the portal vein (n = 5), or was instilled directly into the stomach (n = 5) or the duodenum (n = 5).

After intravenous or intraportal infusion of the drug, the total body clearance of YJA-20379-8 (18.1 and 19.7 mL min−1 kg−1 based on plasma data) was considerably lower than the reported cardiac output (296 mL min−1 kg−1 based on blood data) in rats. This data indicated that the first-pass effect of YJA-20379-8 by the lung and heart was negligible. The areas under the plasma concentration-time curve from time zero to time infinity (AUC) after intravenous or intraportal administration of YJA-20379-8 (2760 and 2540 μg min mL−1) were not significantly different, indicating that the hepatic first-pass effect of the drug was also negligible in rats.

After intragastric or intraduodenal instillation of YJA-20379-8, the extent of absolute oral bioavailability was 18.2 and 33.8%, respectively. Based on gastrointestinal recovery studies, approximately 86.5 and 91.2% of YJA-20379-8 was absorbed from rat gastrointestinal tract after intragastric or intraduodenal instillation, respectively. The data indicated that gastrointestinal and intestinal first-pass effects of YJA-20379-8 were approximately 68% (86.5–18.2) and 57% (91.2–33.8), respectively. The AUC0-24h values of YJA-20379-8 were significantly different between intragastric and intraduodenal instillation, indicating that the gastric first-pass effect of the drug was approximately 10% in rats. Therefore, it could be concluded that the low F value of YJA-20379-8 after oral administration of the drug could be due to a considerable (approx. 60%) intestinal first-pass effect in rats.
Insulin Delivery Governed by Covalently Modified Lectin-Glycogen Gels Sensitive to Glucose
Authors: Tanna S , Taylor M J , Adams G
Published: October 2002

A glucose-sensitive gel formulation containing concanavalin A and glycogen has been reported previously. Precipitation resulting from the addition of concanavalin A to glycogen has been documented, but the formation of glucose-sensitive gels based on lectin-glycogen interactions is novel and used here in our studies. An improved in-vitro self-regulating drug-delivery system, using covalently modified glucose-sensitive gels based on concanavalin A and a polysaccharide displacement mechanism, is described. The successful use of the covalently modified gels addresses a problem identified previously where significant leaching of the mitogenic lectin from the gel membranes of non-coupled gels was encountered.

Concanavalin A was covalently coupled to glycogen by use of derivatives of Schiff's bases. The resulting gels, like the non-coupled gels, were shown to undergo a gel-sol transformation in response to glucose. Insulin delivery was demonstrated using this covalently modified system in conditions of repeated glucose triggering at 20°C and 37°C. The magnitude of the response was less variable than for the dextran-based gels studied previously.

The performance of this system has been improved in terms of concanavalin A leaching. This could, therefore, be used as the basis of the design of a self-regulating drug-delivery device for therapeutic agents used to treat diabetes mellitus.
Conjugation of an Anti-B-cell Lymphoma Monoclonal Antibody, LL2, to Long-circulating Drug-carrier Lipid Emulsions
Authors: Lundberg Bo B , Griffiths Gary , Hansen Hans J
Published: October 2002

Long-circulating submicron lipid emulsions, stabilized with poly(ethylene glycol)-modified phosphatidylethanolamine (PEG-PE), are promising drug carriers with substantial capacity for solubilization of lipophilic anticancer agents. This study describes the conjugation of the anti-B-cell lymphoma monoclonal antibody LL2 to the surface of lipid-emulsion globules by use of a novel poly(ethylene glycol)-based heterobifunctional coupling agent.

The efficiency of coupling of LL2 to the lipid emulsion was 85% (approx.) and essentially independent of the LL2/emulsion particle ratio and amount of surface-bound PEG-PE. Results from sucrose-gradient centrifugation and Sepharose CL-4B gel filtration indicated stable binding of the antibody to the emulsion. The immunoreactivity of the emulsion-LL2 conjugates was tested with alkaline phosphatase-conjugated LL2 against a monoclonal anti-idiotype antibody, WN. The binding of the conjugates to WN increased with increasing surface density of LL2 up to 40 monoclonal antibodies/emulsion particle, and exceeded that for the free monoclonal antibody (approx. 20 molecules/particle). Results from competitive-binding ELISA were indicative of similar displacement curves for free LL2 and emulsion-LL2 conjugates. Direct cellular ELISA revealed similar binding of emulsion-LL2 complexes to three types of Burkitt's lymphoma cell lines, Raji, Ramos and Daudi.

The results from this study indicate that emulsion-LL2 complexes might be a useful drug-carrier system for more specific delivery of anticancer drugs to B-cell malignancy.
Delivery of Erythromycin to Subcutaneous Tissues in Rats by Means of a Trans-phase Delivery System
Authors: Peng Lynnus , Nimni Marcel E
Published: October 2002

Topical administration of antibiotics is associated with reduced risk of systemic side-effects and alteration of gut microflora, and results in higher concentrations of antibiotics at the site of application (and so a lower dose of the drug is required). In conditions such as acne vulgaris, infiltration of the antibiotics into the infected subcutaneous layers is highly desirable. A trans-phase delivery system (TPDS), a mixture of benzyl alcohol, acetone and isopropanol, has been shown to enhance the effective transport of the antibiotic erythromycin across the epidermal barrier and enhance accumulation in the dermis.

Two formulations containing N-methyl[14C]erythromycin were compared, a TPDS solution and a propylene glycol solution. They were applied to the dorsal areas of 4–6 week old Fischer rats and tissues were removed for analysis of radioactivity after 2, 4, 8, 12 or 24 h and skin was biopsied and sectioned for autoradiography. The erythromycin dissolved in the TPDS solvent mixture penetrated the stratum corneum and a relatively high concentration was maintained in adjacent tissues for up to 24 h. Penetration was very effective and the erythromycin was detected in significant amounts in the underlying muscle, various organs and later in the urine. In contrast the propylene glycol carrier, probably because of its primarily hydrophilic character, caused the erythromycin to traverse tissue barriers rapidly and appear in the urine. Microautoradiographs qualitatively revealed progressive disappearance of radioactivity from the surface; this correlated with results obtained by direct isotope counting. The route of penetration, in addition to following the interkeratinocyte spaces, seemed to include the perimeter of the pilosebaceous glands and their appendages before diffusion into the capillaries. The propylene glycol solution seemed to traverse the epidermis and the papillary and reticular dermis more rapidly, which might explain its rapid appearance in the urine. These data suggest that the different solutions penetrate the skin by different mechanisms.
Disposition of Morphine in Tissues of the Pregnant Rat and Foetus Following Single and Continuous Intraperitoneal Administration to the Mother
Authors: Devane C L , Simpkins J W , Boulton D W , Laizure S C , Miller R L
Published: October 2002

Foetal exposure to maternally administered opiates such as morphine represent a serious human health problem but disposition studies in man are difficult to perform. Morphine disposition was therefore investigated in pregnant rats and their foetuses near term as a model. Disposition was examined either following intraperitoneal dosing as a single dose or continuous infusion. A high-pressure liquid chromatography assay for morphine in plasma and tissue was developed and validated.

Following the single morphine dose, foetal distribution was rapid and concentrations in foetal and placental tissue were from 2.6 (whole foetus) to 27.6 (placenta) times higher compared with maternal plasma. The rank order of the area under the concentration vs time curve (AUC) of morphine in tissues was: placenta ≥ foetal liver > foetal brain > whole foetus > maternal brain. The foetal brain to maternal brain AUC ratio for morphine was 9.5, suggesting large differences in their blood-brain barrier permeability. Following continuous administration of morphine there were significant linear relationships between maternal plasma and tissue concentrations with the same rank order as the single dose study. However, following continuous administration the relative amount of morphine in placenta and foetal liver was reduced by half and one-third, respectively, compared with the single dose study.

These results document why the rat foetus is particularly susceptible to the pharmaco-dynamic effects of morphine following maternal administration.
Effects of Some Malian Medicinal Plants on the Respiratory Tract of Guinea-pigs
Authors: Occhiuto F , Sanogo R , Germano M P , Keita A , D'Angelo V , De Pasquale R
Published: October 2002

Crossopteryx febrifuga, Pteleopsis suberosa and Entada africana are used in Mali traditional medicine for fever and various respiratory diseases. We have investigated the effects of these three drugs in the form of a decoction on the respiratory tract using different experimental models.

On citric acid-induced cough in guinea-pigs, the three drugs significantly decreased the number of coughs at the doses of 250 (P < 0.01), 500 (P < 0.05; P < 0.01) and 1000 (P < 0.01)mg kg−1. The percent inhibition was respectively 62.86, 69.03 and 77.44% for C. febrifuga, 57.80, 53.90 and 61.40% for E africana, and 37.13, 42.44 and 73.72% for P. suberosa. Codeine phosphate (10 mg kg−1) used as reference drug showed an inhibition of 76.32%.

E africana (1000 mg kg−1) reduced (65% inhibition) significantly (P < 0.05) broncho-constriction induced by histamine (99.25% and 34.00% for control and extract, respectively). Furthermore, E africana (1000 mg kg−1) provoked a bronchodilatation response when administered under basal conditions.

On antigen-induced bronchospasm, C. febrifuga protected (54% inhibition) sensitized guinea-pigs with a pulmonary ventilation pressure (PVP) of 24.87% (control value < 55.00%). P. suberosa was inactive in both experimental models. The reference drug, disodium cromoglycate (10 mg kg−1, i.v.) protected significantly (P < 0.05) with a PVP of 12.00% (78% of inhibition).

This study confirmed the traditional use of these plants in the treatment of cough and other respiratory disorders.
The Evaluation of Long-term Effects of Cinnamon Bark and Olive Leaf on Toxicity Induced by Streptozotocin Administration to Rats
Authors: Onderoglu Selda , Sozer Sumru , Erbil K Mine , Ortac Ragip , Lermioglu FERZAN
Published: October 2002

The effects of cinnamon bark and olive leaf have been investigated on streptozotocin-induced tissue injury, and some biochemical and haematological changes in rats. The effects on glycaemia were also evaluated.

Long-term administration of olive leaf caused significant improvement in tissue injury induced by streptozotocin treatment; the effect of cinnamon bark was less extent. No effects on blood glucose levels were detected. However, significant decreases in some increased biochemical and haematological parameters of streptozotocin-treated rats were observed. Aspartate aminotransferase, urea and cholesterol levels were significantly decreased by treatment with both plant materials, and alanine aminotransferase by treatment with olive leaf. Cinnamon bark also caused a significant decrease in platelet counts. In addition, any visible toxicity, except decrease in body weight gain, attributable to the long-term use of plant materials was not established in normal rats.

The data indicate that long-term use of olive leaf and cinnamon bark may provide benefit against diabetic conditions. Determination of underlying mechanism(s) of beneficial effects, toxicity to other systems and clinical assessments of related plant materials are major topics requiring further studies.
Stability of Diclofenac Sodium in the Inclusion Complex with β-Cyclodextrin in the Solid State
Authors: Cwiertnia Barbara , Hladon Teresa , Stobiecki Maciej
Published: October 2002

The aim of this study was to characterize the thermal stability of diclofenac sodium both alone and in the inclusion complex with β-cyclodextrin in the solid state, by determination of the number of the products of its decomposition, which were identified by GC-MS.

The molar ratio of diclofenac sodium in the inclusion complex with β-cyclodextrin was 1:1. The decomposition of diclofenac sodium both alone and in inclusion complex with β-cyclodextrin occurred according to the first-order reaction. The HPLC of the samples thermostated at 80°C gave five products of decomposition, which were identified by GC-MS.

Diclofenac sodium in the inclusion complex with β-cyclodextrin was more thermally stable. Thermal decomposition of diclofenac sodium leads to formation of five products, of which 4-chloro-10H-9-acridinone had not been reported previously in the literature.
Pharmacokinetic Differences between Chlorofluorocarbon and Chlorofluorocarbon-free Metered Dose Inhalers of Beclomethasone Dipropionate in Adult Asthmatics
Authors: Harrison Lester I , Soria Inmaculada , Cline Ann C , Ekholm Bruce P
Published: October 2002

We have compared the serum pharmacokinetics of the metabolites of beclomethasone dipropionate after inhalation from chlorofluorocarbon (CFC) and hydrofluoroalkane HFA-134a (HFA) formulations in asthmatic patients.

Twenty-three patients completed this open-label, randomized, single-dose, three-period crossover study. Each patient received in separate periods 200 μg or 400 μg HFA-beclomethasone dipropionate, or 400 μg CFC-beclomethasone dipropionate. Venous blood samples were collected over 24 h for the determination of beclomethasone esters and beclomethasone in the serum.

Significant differences in pharmacokinetics following HFA– and CFC-beclomethasone dipropionate were observed. Following a 400 μg beclomethasone dipropionate dose, the HFA formulation gave mean maximum concentrations (Cmax) and area under the curve (AUC) values of beclomethasone esters of USS pg rnL−1 and 4328 pg h mL−1, respectively, and beclomethasone Cmax and AUC values of 69 pg mL−1 and 682 pg h mL−1, respectively. These values were approximately 2–3-fold those seen with the CFC formulation (beclomethasone esters Cmax and AUC of 380 pg mL−1 and 1764 pg h mL−1, respectively; beclomethasone Cmax and AUC of 41 pg mL−1 and 366 pg h mL−1, respectively). Beclomethasone esters, the major component of beclomethasone dipropionate in the serum, peaked significantly earlier for the HFA formulation (0.8 h) than for the CFC formulation (2h). Tests for dose proportionality of beclomethasone esters pharmacokinetics following HFA-beclomethasone dipropionate showed that the two hydrofluoroalkane strengths were proportional.

The more rapid and greater efficiency of systemic drug delivery of the HFA formulation compared with the CFC formulation can be explained if most of each inhalation from CFC-beclomethasone dipropionate is swallowed and absorbed orally, whereas most of each inhalation from HFA-beclomethasone dipropionate is absorbed through the lungs. There is a need for comprehensive dose-response efficacy trials, with the use of the steep portion of the dose-response relationship, to evaluate the significance of these pharmacokinetic differences.
Inhibition of Aldo-keto Reductases by Phenobarbital Alters Metabolism, Pharmacokinetics and Toxicity of Doxorubicin in Rats
Authors: Behnia Kamelia , Boroujerdi Mehdi
Published: October 2002

Doxorubicin is an effective anticancer agent that is limited by numerous adverse effects, cardiotoxicity causing the most concern. Its alcohol metabolite, doxorubicinol, and free radicals have been implicated in the aetiology of this toxicity. This study was based on the premise that inhibition of aldo-keto reductases would improve the efficacy of doxorubicin by reducing its toxic metabolites and modifying its pharmacokinetics. We assessed the effect of in-vitro inhibition of aldo-keto reductases on the metabolism of doxorubicin in cytosolic fractions of heart and liver of rats in the presence of Na-phenobarbital.

The inhibition was confirmed by a significant reduction in the formation of doxorubicinol. The results of the in-vitro study were further evaluated in-vivo. The concentrations of doxorubicin in plasma, bile and urine and its major metabolites in bile and urine were measured in Na-phenobarbital-pretreated rats. Each rat received 100 mg kg−1/day intraperitoneal injection of sodium phenobarbital for three days followed by a single intravenous dose of 10 mg kg−1 [14C-14]doxorubicin (sp. act. 0.2 μCi mg−1) on the fourth day. The levels of drug in all biological samples were measured by HPLC. The pretreatment resulted in an increase in biological half-life (5.8 ± 1.5 vs 3.7 ± 0.93 h control group, P < 0.05) and area under plasma concentration-time curve (19.6 ± 1.7 vs 14.65 ± 1.68 mg h L−1 control group, P < 0.05). The cumulative amount of doxorubicinol in the bile and urine of pretreated animals was reduced significantly. In terms of % dose, the amount in the bile declined from 4.2 ± 0.8% in control to 2.4 ± 0.3% and in urine from 0.18 ± 0.08% to 0.12 ± 0.07%. There were no significant changes in doxorubicin aglycone and doxorubicinol aglycone. Serum creatine kinase levels were measured as a biomarker of damage to cardiac muscle. The area under creatine kinase level-time curve was reduced by approximately 50% in phenobarbital-pretreated animals.

The results indicate that the inhibition of aldo-keto reductase could provide a useful approach to improve the safety of doxorubicin by reducing its alcohol metabolite. Furthermore, if the reduction in the area under the serum creatine kinase-time curve represents a reduced damage to heart muscle, it can be concluded that doxorubicinol plays an important role in this injury.
Development and validation of a technique for strain measurement inside polymethyl methacrylate
Authors: Cristofolini L , Viceconti M
Published: October 2002

There are many instances where it is necessary to measure strains inside polymethyl methacrylate. For instance, most cemented prosthetic devices fail owing to cement failure. Thus, it is important to measure the cement stresses in vitro, in order to optimize the design. Measuring internal strains with an embedded gauge is extremely difficult. The techniques proposed in the literature either are inaccurate or require large-scale models. In the present work a technique is proposed where a single strain gauge rosette is used. The strain gauge is calibrated to correct the errors deriving from the pressure acting on the grid. Thus accurate measurements can be obtained with a small sensor. The errors associated with this technique are estimated. A pilot study is presented (a) to verify whether the procedure can be applied to the actual geometry of the prosthesis, (b) to verify whether the gauges could safely be inserted into the femur, (c) to estimate the variability of this preparation and (d) to test the robustness of the preparation to repeated loading. Promising results were found in terms of accuracy, precision and robustness of the technique.
Conditions of yield and cyclic plasticity around inclusions
Authors: Ciavarella M
Published: October 2002

In this paper the stress field in the proximity of a circular (cylindrical) inclusion is considered. The conditions for in-plane plastic flow in the matrix are examined from a classical elasticity solution obtained by Goodier. Elementary cases are considered such as remote loading ranging from pure tensile and pure shear to equibiaxial tension. For proportional loading, it is argued that the upper bound to the shakedown limit is always twice the elastic limit; therefore, within the limits of our assumptions, if the elastic stress concentration for the equivalent stress is greater than two, there is a possibility of cyclic plasticity before bulk yielding, which means that possibly an arbitrarily large plastic strain can cumulate with increasingly high risk of exhaustion of ductility and void nucleation or detachment of the interface.

Consequently, conditions under which it is possible to reach twice the elastic limit before full-scale yielding are shown in the Dundurs plane representing all possible combinations of elastic parameters. Following these lines, it is shown that there is no possibility of cyclic plasticity under remote shear; there is a limited area of the Dundurs plane for tension, including the hole case; finally, in the equibiaxial limiting case, cyclic plasticity is always possible for any combination of elastic properties.
Variable material property method in the analysis of cold-worked fastener holes
Authors: Jahed H , Lambert S B , Dubey R N
Published: October 2002

Based on a general axisymmetric method of elastic-plastic analysis presented by Jahed and Dubey, elastic-plastic boundaries and residual stress fields induced by cold expansion of fastener holes is predicted. The method uses a linear elastic solution to construct an elastic-plastic solution. The material parameters are treated as field variables and their spatial distributions are obtained as part of the solution. This method uses the actual loading-unloading behaviour of the material and therefore is capable of predicting an accurate residual stress field. Results obtained here are compared with available experimental and finite element results. The agreement of the results with experimental measurements is very good. It is shown that employment of the actual unloading material curve can make a significant change in residual field prediction.
Frictional contact analysis of coated axisymmetric bodies using the boundary element method
Authors: de Lacerda L. A , Wrobel L. C
Published: October 2002

This paper presents a boundary element analysis of the contact mechanics between elastic indenters and other compliant structures with hard coatings of different properties and thicknesses. Two types of indenter are considered: spherical and conical. The first produces a non-linear contact problem while the latter, used in the soft impresser hardness-testing technique, has a flat tip which results in a conformal type of contact. Frictional conditions are introduced and partial slip phenomena observed. The relevance of friction is verified in all cases. An efficient iterative axisymmetric boundary element formulation has been developed for this purpose, which incorporates features such as subregion modelling and a fast solution procedure. Results with the two types of indenter are compared with available analytical expressions and a commercial finite element package.
Modelling and simulation of the delamination in composite materials
Authors: Vieira Carneiro C. A , Savi M. A
Published: October 2002

Delamination is a phenomenon characterized by the loss of adhesion between two adjacent laminae. This is a damage process frequently observed in composite materials and it may cause either loss of structural stiffness or total failure of the laminate. This contribution presents a model to describe composite delamination. The proposed model considers a laminate with a finite thickness interlayer. Interlaminar stresses are evaluated from a modified lamination theory. This result is used as input in the constitutive adhesion model which describes the damage evolution of the interlayer. An iterative numerical procedure is developed, solving the model equations separately. This work considers numerical simulations of a laminated tube and a laminated bar as applications of the proposed general formulation. Numerical results are capable of capturing the general behaviour of experimental data.
Development of a representative test specimen for frictional contact in spline joint couplings
Authors: Leen S. B , Hyde T. R , Williams E. J , Becker A. A , McColl I. R , Hyde T. H , Taylor J. W
Published: October 2002

The frictional contact conditions in a helical spline joint coupling under torsional and axial loads are studied using finite element analyses. Comparisons of spline root torsional stresses are made with photoelastic measurements. Surface contact tractions, relative slip distributions and subsurface localized stress component and equivalent stress distributions are presented for both the external and the internal spline contact surfaces. The work is important as a basis for understanding and predicting the fatigue, contact fatigue, fretting fatigue, wear and fretting wear characteristics of the coupling. A representative test specimen concept is presented which seeks to capture the local contact variable distributions in the spline coupling, with a view to predicting the wear and the contact and fretting fatigue performance of the coupling.
Measurement of cyclic bending strains in steel wire rope
Authors: Ridge I. M L , Zheng J , Chaplin C. R
Published: October 2002

This paper reports strain gauge measurements of cyclic bending strain in the wires of a six-strand right-handed Lang's lay steel wire rope running on and off a pulley. The paper describes the measurement procedures and presents the results for the two tests conducted which had different gauge configurations along and around the sample. It was found that the strain waveforms observed had some similarities with those reported elsewhere and the magnitudes of strains matched theoretical predictions. However, in contrast with behaviour reported for fluctuating tension, the initial differences between and along wires rapidly attenuated. This observation helps to explain reported similarities in bending fatigue performance of ropes from different sources which contrasts with the very significant differences in characteristics found in tensile fatigue. The dependence of wire strain amplitude on rope bending deformation further contrasts with tensile fatigue in which wire strain range is dependent on the local sharing of axial load.
Flexural behaviour of a curved orthotropic beam on an elastic foundation
Authors: Shenoi R A , Wang W
Published: October 2002

This paper is concerned with the mechanical behaviour of a curved orthotropic beam on an elastic foundation under flexural loading. The differential equation in this case is derived from force-moment equilibrium consideratios and classical laminated orthotropic plate theory. General solutions for various loading conditions are derived using a stress function approach. Finally, the effects of various parameters such as the anisotropy ratio, foundation modulus and radius of the beam on stresses are presented from a design perspective.
Deformations and stresses in pin-loaded tubes: Multiple holes and effects of various loadings
Authors: Ahmad I , Stanley P
Published: October 2002

Deformations and stresses have been determined experimentally in a pin-loaded tube configuration comprising two adjacent and identical hole pairs with fitted pins in a cylindrical tube. The tube was loaded in axial tension applied through one or both of the pins; both parallel and crossed (i.e. perpendicular) pin-axis combinations have been studied. The results are presented in non-dimensional form and discussed. Results are also given for two typical pin-tube configurations subjected, in turn, to axial tension, axial compression, bending in the plane containing the axes of the tube and pin, and torsion about the tube axis.
A photoelastic analysis of crescent-shaped cracks in bolts
Authors: Hobbs J , Burguete R , Heyes P , Patterson E
Published: October 2002

Three-dimensional photoelasticity was used to analyse the effect of crack shape on the stress intensity factors (SIFs) at the tips of cracks in threaded connectors under axial and eccentric loads. The results show that the shape of the crack does not affect the maximum SIF occurring at the middle of the crack front. However, it does influence the distribution around the crack front, with the KI/ Ko values decreasing more rapidly towards the end of the crack front for more crescent-shaped cracks. Despite the complexity of the geometry, the SIFs were found to be predominantly mode I. Eccentric loading was found to increase the SIFs at the centre of the crack front slightly. The crack shape employed in this study was different from those used by earlier investigators but was based on evidence from fatigue tests.
Determining Young's modulus of conductive thin films by a thermal bend beam test
Authors: Shen W , Tang C Y , Li W , Peng L. H
Published: October 2002

An experimental method used to measure the Young's modulus of the conductive thin film is proposed in this paper. This technology has utilized the electrothermal effect and strain response of conductive thin film coatings on glass substrates. On the basis of the thermo-elastic analysis of composite mechanics, the measurement principle and corresponding formula are given. The Young's modulus of conductive SnO2 thin film has been estimated by means of the formula and the thermal bend beam test presented.
Elasto-plastic stress and strain behaviour at notch roots under monotonic and cyclic loadings
Authors: Zeng Z , Fatemi A
Published: October 2002

Notch deformation behaviour under monotonic and cyclic loading conditions was investigated using circumferentially notched round bar and double-notched flat plate geometries, each with two different notch concentration factors. Notch strains for the double-notched plate geometry were measured with the use of miniature strain gauges bonded to specimens made of a vanadium-based microalloyed steel. Elastic as well as elasto-plastic finite element analyses of the two geometries were performed. Notch root strains and stresses were predicted by employing the linear rule, Neuber's rule and Glinka's rule relationships under both monotonic and cyclic loading conditions. The predicted results are compared with those from elastic—plastic finite element analyses and strain gauge measurements. Effects of notch constraint and the material stress-strain curve on the notch root stress and strain predictions are also discussed.
An assessment of ASME III and CEN TC54 methods of determining plastic and limit loads for pressure system components
Authors: Moffat D. G , Hsieh M F , Lynch M
Published: October 2002

The paper considers three different pressure system components—a nozzle in a torisphere subjected to moment loading, a piping branch junction subjected to out-of-plane moment loading and an unpierced torispherical head under pressure loading. The results from non-linear, finite element, stress analyses are used to compare the limit and plastic loads obtained using the ASME III twice-elastic-slope and the CEN TC54 tangent intersection definitions. The results highlight the difficulties involved in quantifying limit loads and plastic loads for such components.
Generalized bending of a plate with a circular inclusion of arbitrary rigidity
Authors: Bert C. W
Published: October 2002

The paper presents an exact closed-form solution for a thin isotropic plate containing a circular elastic inclusion and subjected to arbitrary bending moments at large distances from the hole. Quantitative results are presented for the bending stress concentration factors for the plate and for the inclusion.
Experimental study of fast ductile crack growth in aluminium alloy 2014 panels
Authors: Medina-Velarde J L , Petrinic N , Ruiz C
Published: October 2002

An experimental investigation into the crack propagation in aluminium alloy 2014 is described. Panels, 120 mm wide by 300 mm long were pre-loaded to a constant force applied by two identical compressed gas cylinders following which a crack was induced by forcing open a pre-machined notch with a wedge travelling at approximately 30 m/s. The crack growth was recorded by high-speed photography. The crack tip opening angle of a rapidly propagating crack was measured from plain flat specimens. In addition, crack arrestors in the form of slots and ribs have been studied. The results highlight the effect of rolling direction of the material and constitute a basis for the validation of numerical modelling tools.
Elastic-plastic analyses for surface cracked plates under combined bending and tension
Authors: Kim Y-J , Shim D-J , Choi J-B , Kim Y-J
Published: October 2002

This paper provides an engineering J estimation equation for surface cracked plates under combined bending and tension. The proposed equation is based on the reference stress approach, and the most relevant normalizing loads to define the reference stress for accurate J estimations are given for surface cracked plates under combined bending and tension. Comparisons with J results from extensive three-dimensional finite element (FE) analyses, covering a wide range of crack geometry, plate geometry and loading combination, show overall good agreement not only at the deepest point but also at arbitrary points along the crack front. For pure tension, agreement between the estimated J vlaues and the FE results is excellent, even at the surface point. On the other hand, for pure bending and combined bending and tension, the estimated J values become less accurate for locations close to the surface point.
Small sample theory for reliability design
Authors: Xiong J , Shenoi R A , Gao Z
Published: October 2002

This paper outlines a new technique to address the paucity of data in assessing fatigue strength reliability. New formulations are presented for scatter factors, dealing with conditions where the population standard deviation is unavailable and where fatigue test results are incomplete. Reduction factor formulae for these two cases are also given. Finally, the concepts are applied to two sets of experimental data, demonstrating the practical and economic use of the proposed technique. It is shown from these examples that, when the standard deviation of the population is unknown, then safe fatigue life and fatigue strength can be obtained realistically according to the small sample test data using the new formulae for the fatigue life scatter factors and for the fatigue strength reduction factor.
Shape optimization of fillets by the boundary element method
Authors: Parvizian J , Fenner R. T
Published: October 2002

The boundary element method is established as a powerful technique for the stress analysis needed in shape design optimization. Two alternative algorithms for determining the optimum are available, using either sensitivity derivatives or normal movement of the boundary on the basis of local stresses. These algorithms are investigated in relation to the problem of shape optimization of fillets in plates under tension. The results are compared with others published previously, and it is concluded that, particularly for problems such as fillets, where the feasible region for design changes is restricted by practical considerations, the normal movement approach is preferable, and avoids the need to calculate large numbers of sensitivity derivatives.
The connection between the elastic and plastic components of residual strain and residual stress
Authors: Hills D. A
Published: October 2002

It is shown by reference to the example of the over-bent beam problem that the residual stress state is related to the elastic component of residual strain.
Influence of fibre on the cutting stress state in machining idealized glass fibre composite
Authors: Wern C W , Ramulu M
Published: October 2002

The machining of an idealized glass fibre reinforced plastic (GFRP) was examined using photo-elasticity, dynamometry and optical microscopy. Cutting stresses at the glass roving and roving-matrix interface were evaluated using experimental and numerical methods. Experimentally observed isochromatics and measured forces in the orthogonal cutting of GFRP were shown to be affected by the reinforcement and its orientation. Machining stresses and machined surface damage were found to be highest when machining materials with roving oriented 45° towards the cutting edge.
Benchmarking of a destructive technique to determine residual stresses in thick-walled axisymmetric components
Authors: Sharman D J , Stark H L , Kelly D W
Published: October 2002

A proposed destructive technique to determine residual stresses in thick-walled axisymmetric pressure vessels employs incremental strain gauge data in a finite element algorithm to construct the initial residual stress distribution. The data acquisition component of the proposed technique has similarities with Sachs' bore out method, enabling independently obtained data to be employed by the finite element algorithm. A comparison between the two methods based on the same strain data enables the accuracy of the finite element algorithm to be assessed. Results to date suggest that the new algorithm determines residual stress distributions to an accuracy comparable with Sachs' bore out method. An advantage that the proposed technique has over Sachs' bore out method is that it can be applied to axisymmetric thick-walled pressure vessels of geometries more complex than plain cylinders.
Computer aided photoelastic stress analysis of a variable-pitch lead screw
Authors: Chen T Y , Lin J S
Published: October 2002

Three-dimensional stress-freezing photoelasticity is applied to analyse the stress in a variable-pitch lead screw at contact with two conical meshing elements. A PC-based image-processing system and the relevant digital techniques are used to collect the photoelastic data, and the cubic technique is used to evaluate the effective stress at the contact region. The model-making and computer aided data collection procedures are described. Contour plots of the effective stress at the contact regions are presented. It was found that the highest effective stress values on the two contact thread surfaces are approximately the same, although the exerting forces are quite different.
Stress intensity factors for semi-elliptical surface cracks in semicircularly notched tension plates
Authors: Lin X B , Smith R A
Published: October 2002

Stress intensity factors for semi-elliptical surface cracks located at the centre of a semicircular edge notch in a finite thickness plate subjected to a remote tensile load are presented in a tabulated format. A wide range of geometry ratios are considered. They are all combinations of the following ratios: the ratio of crack surface half-length to plate half-thickness, c/t = 0.2, 0.4, 0.6, 0.8 and 0.95; the ratio of crack depth to surface half-length, a/c = 0.2, 0.4, 0.6, 0.8 and 1; and the ratio of notch radius to plate half-thickness, r/t = 0.5, 1, 2 and 3. Both the quarter-point displacement and J.-integral methods based on three-dimensional finite element analyses were employed for the calculation of stress intensity factors. The calculation accuracy was studied by analysing the J.-integral path independence and comparing stress intensity factor results with other solutions available in the literature.
A comparison of potential methods for the alleviation of residual stresses in the necks of aluminium alloy thick-walled gas cylinders
Authors: Sharman D J , Stark H L , Kelly D W
Published: October 2002

Tensile circumferential residual stresses are introduced into seamless 6351 aluminium alloy gas cylinder necks at the bore during the heat treatment stage of the manufacturing process. To ascertain the feasibility of a proposed corrective procedure (selective removal of material from the gas cylinder neck) finite element analyses that modelled material removal were undertaken. Results indicate that no significant benefit was gained from the partial removal of bore material. However, removing the inelastically deformed outer surface material is likely to provide the greatest benefit of the four options considered. The material removal option was then compared with an investigation into cold working the gas cylinder neck to favourably modify the quenching residual stresses. Experimental results have indicated that the application of an axially applied compressive load to the gas cylinder neck, inducing bore yielding, favourably modifies the quenching residual stresses. This alternative of cold working the gas cylinder neck appears to be a possible method of favourably modifying the quenching residual stress.
Machining of simulated defects in pipeline steels: A neutron diffraction study of local stress effects
Authors: Clapham L , Krause T W , Sabet-Sharghi R , Micke D , Atherton D L , Rogge R B , Holden T M
Published: October 2002

The most commonly used in-line pipeline inspection tools utilize the magnetic flux leakage (MFL) technique, which is sensitive to the stress state of the pipe wall. Calibration of these MFL tools is often carried out using unstressed pipeline sections containing simulated defects, usually produced by mechanical drilling. There is also strong interest in creating simulated defects in stressed pipe walls, thus simulating corrosion in the field. In this study, neutron diffraction is used to map the local stresses surrounding mechanically and electrochemically drilled holes in a steel plate sample. Holes were drilled in unstressed samples, as well as samples held at a constant 80 MPa uniaxial stress. Mechanical drilling into a stressed sample was found to induce considerable residual stresses around the hole. Conversely, electrochemical drilling did not create a residual stress field in the vicinity of the hole.