bluuebunny/crossref_metadata_2025 huggingface dataset:
Periventricular lucency evaluated by second‐derivative finger plethysmography
Authors: Iwamoto Toshihiko , Miyaji Hiroko , Kanaya Kiyoshi , Takasaki Masaru
Published: March 2003

Background:

The purpose of the present paper was to clarify the etiologic and pathophysiologic bases of periventricular lucency (PVL).

Methods:

The relationship between PVL severity and hemodynamic variables derived by second‐derivative finger plethysmography (SD‐PTG) was studied. A total of 307 consecutively examined outpatients 60 years or older (mean age: 77.7 years; 149 men, 158 women) was enrolled. On the basis of brain computed tomography, PVL was classified into four grades (0–3) according to a modification of the classification of van Swieten. The grade of PVL was assessed at two points in each patient: anterior and posterior. The heights of the a, b, and d waves on the SD‐PTG waveform were measured from baseline. The b/a ratio, indicating distensibility of the aorta, and the d/a ratio, indicating peripheral resistance, were calculated.

Results:

An anterior PVL of grade 3 had a significantly higher b/a ratio and a significantly lower d/a ratio than that of grade 0 or grade 1 (both P < 0.05). For posterior PVL, the b/a ratio and the d/a ratio were similar for all four grades. The anterior PVL grade was compared with the posterior PVL grade in individual subjects. This comparison yielded six groups: four in which PVL grade was similar (0, 1, 2 or 3) in both regions, one in which the grade for anterior PVL was higher than that for posterior PVL (predominantly anterior group), and one in which the grade for posterior PVL was higher than that for anterior PVL (predominantly posterior group). In patients with predominantly anterior PVL, the b/a ratio and incidence of lacunae were significantly higher than that in patients with predominantly posterior PVL.

Conclusion:

These findings indicate that the frontal white matter is susceptible to hemodynamic stress. It is suggested that decreased aortic distensibility may promote fibrohyaline thickening of the medullary arteries, increasing the risk of PVL.
Guided self‐care using daily recording of peak expiratory flow and diary description for chronic airflow obstruction in the elderly
Authors: Kida Kozui , Katsura Hideki , Yamada Koichi , Motegi Takashi , Mizuno Syoichi
Published: March 2003

Background:

Only a few studies have been reported concerning the effects of guided self‐care programs on elderly patients with chronic airflow obstruction; chronic obstructive pulmonary disease (COPD); and bronchial asthma (BA). The purpose of the present paper was to study the usefulness of guided self‐care in elderly patients with COPD or BA using a diary alone or diary plus daily measurement of peak expiratory flow rate (PEFR).

Methods:

A prospective and randomized study was performed at the Pulmonary Division of the Tokyo Metropolitan Geriatric Hospital. A total of 212 patients (mean age: 76.6 years) with a clinical diagnosis of COPD or BA with mild or no cognitive impairment was studied. All patients were randomly assigned to one of two groups: group I (diary and measurement of daily PEFR; n = 112) or group II (diary alone; n = 100).

Results:

There was no significant difference in the mean number of admissions per month between groups I and II. However, the mean duration of hospitalization was shorter in group I (P < 0.05). The group I COPD subjects had fewer (P < 0.05) and shorter (P < 0.02) periods of admission compared with the group II COPD subjects. This remained true after adjusting for gender, age and forced expiratory volume in 1 s (FEV1.0), but there was no such difference observed for BA subjects. Among subjects in group II, those with COPD showed significantly longer periods of admission than BA subjects (P < 0.05). Better compliance with the PEFR description in group I correlated significantly with the shorter mean duration of hospitalization in the group with higher compliance. This was not found in group II (diary alone). Poor compliance was significantly correlated with advancing age (P < 0.04). However, this was not the case for compliance with the diary. Male subjects showed significantly better compliance in diary description than female subjects (P < 0.04).

Conclusions:

The PEFR recording plus diary notations are useful tools for avoiding hospitalizations due to acute exacerbation of COPD and probably BA in elderly patients. However, a possible limitation is that fewer than half of elderly COPD and BA patients with mild or no cognitive impairment appear to be able to record PEFR properly.
Association of angiotensin‐I converting enzyme DD genotype with influenza pneumonia in the elderly
Authors: Onishi Miyuki , Morimoto Shigeto , Yang Jin , Okaishi Kohya , Katsuya Tomohiro , Shimizu Masumi , Okuro Masashi , Sakurai Shoroku , Onishi Toshio , Ogihara Toshio
Published: March 2003

Background: Although angiotensin‐I converting enzyme (ACE) is known to associate with cough
reflex and inflammatory conditions, and both may participate in influenza pneumonia
in the elderly, no study has been carried out on the association between influenza
pneumonia and the insertion/deletion (I/D) polymorphism of the ACE gene (ACE).

Methods: The subjects were 934 elderly inpatients (mean ± SD age of 82 ± 8
years) in a long‐term care hospital. The association between ACE I/D and the incidence of influenza‐pneumonia events was assessed over a winter season. Data were analyzed by multiple logistic regression analysis, with adjustment for age, gender, already known clinical risk factors, and ACE‐inhibitor use.

Results: During the follow‐up period, 330 patients developed influenza (Directigen FLU‐A)
and 89 developed influenza pneumonia (Center for Disease Control and Prevention (CDC)
criteria with chest X‐ray required), 16 fatal and 73 non‐fatal. Compared to non‐influenza
subjects (n = 604) and influenza patients without pneumonia (n = 241),
ACE DD genotype (vs ID + II) resulted in a significant risk for all pneumonia (relative risk 2.32 [95% CI: 1.30–4.14] and 2.76 [1.39–4.04]), non‐fatal pneumonia (1.91 [1.01–3.63] and 2.57 [1.23–5.39]) and fatal pneumonia (6.27 [1.68–23.3] and 5.15 [1.29–20.5]).

Conclusion: ACE I/D polymorphism is a strong and independent risk indicator of influenza pneumonia events in elderly inpatients.
Protein malnutrition in elderly patients with chronic obstructive pulmonary disease
Authors: Ozeki Tomoko , Fujita Yoshiaki , Kida Kozui
Published: March 2003

Background: It has been suggested that hypermetabolism or reduction of total caloric intake or a combination of both conditions occur in malnourished patients with chronic obstructive pulmonary disease (COPD). It is hypothesized that protein malnutrition plays a role in the metabolism of malnourished elderly COPD patients.

Methods: Thirteen COPD patients (mean age: 75.7 years) with severe obstructive ventilatory disorder were divided into two groups: body mass index greater than 20 (group N; n = 8) and less than 20 (group L; n = 5). A nutritional survey and metabolic study were performed.

Results: Energy balances appeared more highly positive in group L than in group N and serum concentrations of total protein, albumin and transferrin tended to be lower in group L than in group N (all showed no statistically significant difference). The mean protein digestibility did not show any significant difference between the two groups, suggesting that group L subjects digested and absorbed the ingested dietary protein normally. Mean nitrogen balance was more highly positive in group L than in group N. The FEV1 decreased significantly with increases in the basal metabolic rate (BMR), total daily energy expenditure and urinary nitrogen excretion, respectively (all P < 0.05). PaO2 was positively and significantly correlated with serum concentrations of albumin and transferrin (P = 0.001 and P < 0.05), respectively. Body mass index (BMI) was negatively correlated with BMR (P < 0.05).

Conclusions: It is suggested that malnourished COPD patients with lower BMI showed enhanced protein and energy metabolism. Thus, it is likely that malnourished elderly COPD patients could improve through not only supplementation of total carolic intake but also sufficient protein intake.
Intellectual faculties in patients with Alzheimer's disease regress to the level of a 4–5‐year‐old child
Authors: Shoji Mikio , Fukushima Kazuko , Wakayama Mitsuyoshi , Shizuka‐Ikeda Masami , Ikeda Yoshio , Kawakami Atsuko , Sakazume Yuka , Ikeda Masaki , Harigaya Yasuo , Matsubara Etsuro , Kawarabayashi Takeshi , Murakami Tetsuro , Nagano Isao , Manabe Yasuhiro , Abe Koji
Published: March 2003

Background:  The present study investigated when children acquire the cognitive abilities and daily living skills that are lost in Alzheimer's disease.

Methods:  Among a total of 1046 students in kindergarten and elementary schools affiliated with Gunma University, Japan, five female and five male students in each grade were selected at random and examined by the mini‐mental state examination (MMSE) and physical self‐maintenance scale (PSMS). For comparison, a total of 135 outpatients with Alzheimer's disease were examined. The results of MMSE and PSMS from the first visit to Gunma University Hospital after the onset of Alzheimer's disease were used.

Results:  The MMSE score gradually increased from 10 points in the 1st year of kindergarten (age 3 in Japan) to 29 points in the 6th grade of elementary school (age 11 in Japan). The PSMS score increased similarly from 3 points in the 1st year of kindergarten to 6 points in the 6th grade of elementary school. The mean scores of MMSE and PSMS were 17.3 and 3.7 in the Alzheimer patients’ group. These findings suggested that cognitive and daily performance abilities examined by MMSE and PSMS are acquired in childhood during kindergarten and the early grades of elementary school.

Conclusion:  These cognitive and daily performance abilities of Alzheimer's disease outpatients regress to a level of a child between 4 and 5 years old. This simple understanding of Alzheimer's disease patients may contribute to further appropriate care by non‐specialists and caregivers.
Distal pancreatectomy with preservation of the spleen and splenic vessels
Authors: Grodski Simon , Christophi Chris
Published: March 2003

This article draws attention to the concept of distal pancreatectomy with splenic preservation including the splenic artery and vein.
Primary colorectal signet‐ring cell carcinoma in Singapore
Authors: Ooi Boon Swee , Ho Yik Hong , Eu Kong Weng , Seow Choen Francis
Published: March 2003

Background:   Primary colorectal signet‐ring cell carcinoma is a rare but distinctive tumour of the colon and rectum. The clinicopathological features are still controversial. The aim of this study is to review the clinicopathological features and management of this type of tumour in our hospital.

Methods:   The clinicopathological features and survival data of all cases of primary colorectal signet‐ring cell carcinoma were reviewed retrospectively.

Results:   There were nine cases of primary colorectal signet‐ring cell carcinoma in 3000 consecutive colorectal carcinoma patients seen from 1989 to 1999. There were seven male and two female patients with a mean age of 54.7 years. Three patients were younger than 40 years. The common presenting symptoms were rectal bleeding (33%) and small bowel obstruction (33%). Two (22%) patients required emergency surgery due to acute small bowel obstruction. The most common tumour location was the right colon (44%) followed by the rectum (33%). All nine patients presented at a very late stage of disease. A majority (77%) had Dukes’ C disease while two (22%) had Dukes’ D disease with distant dissemination. Peritoneal spread (33%) was the most frequent way of dissemination. There was no patient with liver metastases at the time of diagnosis and initial presentation. The mean survival time was 30 (range 5–108) months. The 5‐year survival rate was 12%.

Conclusions:   Primary colorectal signet‐ring cell carcinoma is frequently diagnosed late with a very poor prognosis. A high incidence of peritoneal seeding and low incidence of liver metastases appears to be a characteristic of signet‐ring cell carcinoma of the colon and rectum.
Complications of biliary T‐tubes after choledochotomy
Authors: Wills Vanessa L. , Gibson Kate , Karihaloo Costa , Jorgensen John O.
Published: March 2003

Background: Traditional management of choledocholithiasis has been supraduodenal choledochotomy, duct exploration and insertion of a T‐tube. This study reviews the complications associated with T‐tube use and assesses whether laparoscopic procedures are associated with an increase in complications relating to T‐tube use.

Methods: Case records from two large public hospitals in New South Wales (Australia) were analysed retrospectively for a 10‐year period using a standardized data collection form. Morbidity, mortality and potential factors influencing the complication rate after choledochotomy and T‐tube insertion were recorded. All complications were reviewed by an experienced biliary surgeon.

Results: T‐tubes were inserted in 274 patients, with 42 patients (15.3%) experiencing a total of 60 complications relating to T‐tube use. Morbidity occurring while the tube was in situ included fluid and electrolyte disturbance (five patients), sepsis (10 patients), premature dislodgement (three patients) and bile leakage (six patients). Complications resulting after planned tube removal included localized pain (13 patients), biliary peritonitis (seven patients), a prolonged biliary fistula (seven patients) and a late bile duct stricture (one patient). T‐tube complications resulted in a prolonged hospital stay (19 days vs 13 days, P = 0.005), 10 additional abdominal operations and two deaths. Complications related to T‐tubes were constant over the study period and were similar between laparoscopic and open cases (13.8%vs 15.5%, P = 0.81).

Conclusions: Although this retrospective review is likely to have underestimated the incidence of T‐tube complications, it has demonstrated significant morbidity associated with T‐tube use. The incidence of these complications has been constant and is unrelated to a laparoscopic approach.
Push enteroscopy: A single centre experience and review of published series
Authors: Chen Robert Y. M. , Taylor Andrew C. F. , Desmond Paul V.
Published: March 2003

Background: To assess the efficacy of push enteroscopy in a single tertiary hospital and review the available literature to assess the overall diagnostic yield of push enteroscopy.

Methods: Review of a database on push enteroscopy in a tertiary hospital from 1997 to 1999. This included 100 consecutive patients who underwent push enteroscopy. Review of all large published series on push enteroscopy to date to obtain an overall diagnostic yield.

Results: The diagnostic yield for patients with gastrointestinal (GI) bleeding was 47% and for patients with suspected small bowel disease was 33%. Angiodysplasia was the most common diagnosis in patients with GI blood loss. Patients with active GI bleeding had a higher diagnostic yield. The procedure was tolerated well and no complications occurred. Review of the literature showed an overall diagnostic yield of 44% (498 of 1136 patients) for patients with GI blood loss and 38% (108 of 286 patients) for suspected small bowel disease.

Conclusions: Push enteroscopy has a good diagnostic yield and is valuable in patients with GI blood loss and suspected small bowel disease.
Incomplete excision of basal cell carcinomas: A retrospective audit
Authors: Dieu Tam , Macleod Allan M.
Published: March 2003

Background: The reported rates of incomplete excision of basal cell carcinoma (BCC) vary widely (5–25%) among centres around the world. Incomplete excision of skin malignancy is one of the 57 clinical indicators developed by the Royal Australasian College of Surgeons and the Australian Council on Healthcare Standards to act as a measure of the standard of surgical care. The study aims to determine the rate of incomplete excision of BCC at a major cancer centre.

Methods: Computerized data and patients’ records were reviewed. From January 1997 to June 2000, a total of 3558 BCC were surgically excised with curative intent, of which 223 were reported to have been removed incompletely.

Results: The overall rate of incomplete excision was 6.3%.

Conclusions: Given the limitations of a retrospective audit and reliability of the data, this result nevertheless compares favourably with reported figures in the literature.
Deep venous thrombosis prophylaxis: Are guidelines being followed?
Authors: Ahmad Hairul A. , Geissler Annalies , MacLellan Donald G.
Published: March 2003

Introduction:  The purposes of the present study were to determine whether patients in The Canberra Hospital are receiving appropriate Deep Venous Thrombosis (DVT) prophylaxis, and to ascertain the awareness of appropriate treatment by clinicians.

Methods:  Part 1 of the present study comprised of a point prevalence study of The Canberra Hospital inpatients. Patients were assessed for the risk of their developing DVT. The prophylaxis they were receiving was documented. In Part 2 of the present study, clinicians at The Canberra Hospital filled out a questionnaire that outlined three case scenarios. They were required to identify the risk group and appropriate prophylaxis for each group. Consultants, registrars and junior medical officers were assessed separately.

Results:  The results of Part 1 of the present study showed that the majority of inpatients in The Canberra Hospital are not receiving appropriate prophylaxes according to international guidelines. Graduated compression stockings are rarely used, and often ineffectively applied. All groups performed poorly in Part 2 of the present study. Participants were frequently unable to identify the risk group for a particular scenario. There was also confusion regarding the appropriate prophylaxis for a particular risk group.

Discussion:  Deep Venous Thrombosis is a major problem among hospitalized patients. However, despite its importance, there is a lack of appropriate prophylaxes being instituted. This, together with the poor performance of the participating clinicians in Part 2 of the present study, indicate that there are significant problems in The Canberra Hospital regarding DVT prophylaxes and that steps need to be taken to overcome these problems.
Surgical strategies in the laparoscopic therapy of cholecystolithiasis and common duct stones
Authors: Ludwig Kaja , Lorenz Dietmar , Koeckerling Ferdinand
Published: March 2003

Background:  The purpose of the present study was to examine the current approach and different strategies adopted for laparoscopic cholecystectomy in Germany.

Methods:  A retrospective survey was conducted at 859 (n = 1200; 67.6%) hospitals in Germany. Data from 123 090 patients who had undergone cholecystectomy were analysed.

Results:  71.9% of the operations were finished laparoscopically (n= 88 537) whereas 22.5% were carried out using the open technique. Conversion to open surgery was required in 7.1% of the laparoscopically started operations. When common bile duct stones were diagnosed preoperatively, 74.4% of the participants favoured the primary endoscopic extraction, following laparoscopic cholecystectomy. In cases of intraoperative diagnoses, laparoscopic cholecystectomy was finished and postoperative primary endoscopic extraction was carried out in more than half of the hospitals (58.4%). Sixteen per cent converted to an open operation with simultaneous exploration of the common duct. Laparoscopic desobstruction of the common bile duct was extremely rare (4.4%). Compared with open cholecystectomy, the results show a lower incidence of postoperative reinterventions (0.9 vs 1.8%) and fatal outcomes (0.04 vs 0.53%) for laparoscopic cholecystectomy. In contrast, common bile duct injuries were more frequent in the laparoscopic cholecystectomy group (0.32 vs 0.12%). The median duration of hospitalization was 6.1 days (range: 2.8−12) in the laparoscopic cholecystectomy group compared with 10.4 days (range: 3−28) in the open cholecystectomy group.

Conclusions:  Laparoscopic cholecystectomy is the standard procedure for the treatment of uncomplicated gallstone disease. There are reasonable differences between the hospitals in type of cholecystectomy for acute cholecystitis, management of common duct stones and intraoperative diagnostics in laparoscopic cholecystectomy, even after adjustment for differences in patient comorbidities.
Chemical injuries: The Tasmanian burns unit experience
Authors: Ricketts Sophie , Kimble Francis W.
Published: March 2003

Background:  Chemical burns account for relatively few admissions to a burns unit. These injuries, however, deserve separate consideration because of their ability to cause continuing tissue destruction, their potential to cause systemic toxicity and the value of early treatment with copious lavage. Widespread inexperience in the treatment of chemical burns highlights the potential for greater levels of general awareness and knowledge.

Methods:  A review of 31 patients with chemical injuries admitted to the Tasmanian Burns Unit at the Royal Hobart Hospital (RHH) was carried out for the years 1989−1999.

Results:  The majority of patients were men aged 20−49 years (mean age: 32 years). Fifty‐one per cent of injuries occurred in a domestic and 38% in an industrial setting. The more common aetiological agents were cement (25%), sulphuric acid (16%) and hydrofluoric acid (16%). The upper and lower extremities were involved in all but four patients and the mean total body surface area affected was 3.4%. The mean length of hospital stay was 9 days with a range of 1−30 days. Management of injuries consisted of either surgical or conservative treatment. The former included debridement and split‐thickness skin grafting or primary closure and the latter of topical treatment with 1% silver sulfadiazine cream and appropriate dressings.

Conclusion:  Widespread inexperience in the treatment of chemical injuries highlights the potential for greater levels of knowledge. This is particularly apparent in the early management of these injuries.
A CRACK GROWTH APPROACH TO LIFE PREDICTION OF SPOT‐WELDED LAP JOINTS
Authors: Newman JA , Dowling NE
Published: March 2003

Fatigue behaviour of spot‐welded lap joints is modelled as a single‐degree‐of‐freedom crack growth problem. Although such a model involves simplification of a complicated problem, predictions are in good agreement with experimental results. The model developed here allows a design engineer to analyse the fatigue behaviour of spot‐welded steel sheets, which are commonly used in structures, without knowledge of metallurgical and fine geometric details of spot‐welds. Only fatigue properties of the sheet metal are needed, so no laboratory facilities are required to generate fatigue data specific to spot‐welds or weld metal.
PLASTIC DAMAGE ANALYSIS FOR THE PROCESS ZONE OF A FATIGUE CRACK
Authors: Zhao  , Zhang
Published: March 2003

The process zone of a mode I fatigue crack is described asymptotically with damage coupled plastic constitutive relations. A parametric study is conducted to obtain the orders and angular distribution modes of stress, strain and damage fields, as well as the profiles of the related process zones. The fatigue crack growth rate is also formulated theoretically.
A finite element model for crack arrestor design in gas pipelines
Authors: O’Donoghue P.E. , Zhuang Z.
Published: March 2003

Steel rings are frequently used as crack arrestor devices in steel gas transmission pipelines to prevent the possibility of long running axial cracks. These arrestors have the effect of reducing the pipe opening as the crack propagates. This decreases the available crack driving force and, as a result, crack arrest can take place. This essentially is a second line of defence against catastrophic failure in the event that crack initiation cannot always be prevented. This paper describes a novel analysis methodology that has been developed to investigate the suitability of these crack arrestors. This is based on a fluid/structure/fracture interaction package, PFRAC. Here, a curved beam element has been implemented into PFRAC to simulate the behaviour of the arrestor. The contact conditions between the pipe wall and the arrestor, along with the various computational procedures, are described here. Several numerical results for a cracked pipe with arrestors are presented along with comparisons with pipes that do not have arrestors.
There is no infinite fatigue life in metallic materials
Authors: Bathias
Published: March 2003

Generally, the shape of the S–N curve beyond 107 cycles is unknown except in some statistical approaches, and this is also true for the fatigue limit. In the case of a statistical approach, the standard deviation applied to the average fatigue limit is certainly not the best way to reduce the risk of rupture in fatigue. Only the exploration of the life range between 106 and 1010 cycles will create a safer basis for modelling.

Today, some piezoelectric fatigue machines are very reliable, capable of producing 1010 cycles in less than 1 week. We based our research on accelerated fatigue tests which were performed at 20 kHz in the gigacyclic fatigue regime in order to study several typical alloys from the aeronautical and space industries.
Stress concentration formulae useful for any shape of notch in a round test specimen under tension and under bending
Authors: Noda  , Takase
Published: March 2003

In this work stress concentration factors, Kt , for a round bar with a circular‐arc or V‐shaped notch are considered on the basis of exact solutions for special cases and accurate numerical results. Then, a set of Kt formulae useful for any shape of notch is proposed. The conclusions can be summarized as follows.

(i) For the limiting cases of deep (d) and shallow (s) notches, the body force method is used to calculate the Kt values. Then, the formulae are obtained as Ktd and Kts .

(ii) On the one hand, upon comparison of Kt  and Ktd it is found that Kt is nearly equal to Ktd if the notch is deep or blunt.

(iii) On the other hand, if the notch is sharp or shallow, Kt is mainly controlled by Kts and the notch depth.

(iv) The notch shape is classified into several groups according to the notch radius and notch depth. Then, the least‐squares method is applied for the calculation of Kt /Ktd and Kt /Kts .

(v) Finally, a set of convenient formulae is proposed that are useful for any shape of notch in a round test specimen. The formulae give SCFs with <1% error for any shape of notch.
A fracture plane approach in multiaxial high‐cycle fatigue of metals
Authors: Carpinteri  , Brighenti  , Spagnoli
Published: March 2003

The high‐cycle fatigue behaviour of metals under multiaxial loading is examined. By employing the weight function method, the authors propose to correlate the fatigue fracture plane orientation with the averaged principal stress directions. The results derived by applying such an approach are compared with the experimental data collected from the relevant literature, concerning different types of metals under in‐phase or out‐of‐phase sinusoidal biaxial normal and shear stress states. Theoretical results determined by McDiarmid are also reported.
Complex fracture parameters for an interface crack between twohardening materials: a photoelastic study
Authors: Ekman  , Marsavina  , Nurse
Published: March 2003

In this paper, complex stress intensity factors (SIFs) at an interface crack are determined for a range of applied loads, crack lengths and remote mode mixes using automated photoelasticity. The specimen geometries comprise epoxy resin and aluminium alloy halves bonded together, and are loaded in either compact tension in mixed‐mode conditions or in three‐point bend under mode I conditions. In the experiments, full‐field isochromatic data were obtained from the epoxy half using an established phase‐stepping technique. A reworked approach to the determination of the SIFs was developed by combining a least‐squares over‐deterministic method for fitting crack‐tip stress equations to the data and a weighting factor that ensures that only data in the singularity zone are used. For comparison, some of the specimens were tested using a linear‐elastic finite element (FE) analysis and/or by experiment using homogeneous test specimens. Excellent agreement between the experimental and numerical SIF moduli was achieved for remote mode I loadings. However, for good agreement to be made between the phase angle results requires an additional phase term to be added to the FE solution at each load to account for the development of a crack‐tip plastic zone. Further, results for the SIFs from remote mixed‐mode loadings of the compact tension specimen only have a meaningful interpretation in light of small‐scale yielding conditions. It is shown, qualitatively, that the experiments verify some of the predictions made in the literature of asymptotic behaviour at interface crack tips from results of elasto‐plastic FE analyses.
Fatigue crack closure analysis of bridged cracks representing composite repairs
Authors: Wang C. H.
Published: March 2003

This article presents an analytical and numerical study of the fatigue crack‐closure behaviour of a bridged crack representing a crack that has been repaired by a composite patch. It is shown that, provided that the plate stress beneath the patch is less than 40% of the material’s yield stress, the crack‐closure stress of a patched crack is approximately equal to that of an unbridged crack under small‐scale yielding, depending only on the stress ratio. Furthermore, it is shown that the transient crack‐closure behaviour of a patched crack subjected to variable amplitude loading can be determined by analysing an unpatched crack subjected to the same stress intensity factor history. Based on these findings, it is proposed that the fatigue crack closure of a patched crack can be determined by analysing an unpatched centre crack subjected to an adjusted stress, for which an explicit expression is given. Predictions based on the proposed method are shown to correlate very well with experimental results obtained under two aircraft loading spectra.
External surface cracks in shells under cyclic internal pressure
Authors: Carpinteri Andrea , Brighenti Roberto , Spagnoli Andrea
Published: March 2003

The stress analysis and fatigue crack growth behaviour of a part‐through‐cracked double‐curvature thin‐walled shell is examined. An external surface crack is assumed to lie in one of the principal curvature planes of the shell, and to present a semi‐elliptical shape. The stress intensity factors (SIFs) along the crack front for different elementary opening stresses acting on the crack faces are determined through a three‐dimensional finite element analysis. Then approximate values of SIF in the case of a cracked pressure vessel are computed by employing the above results together with the superposition principle and the power series expansion of the actual opening stress. Finally, a numerical simulation procedure is carried out to predict the crack growth under cyclic internal pressure. Some results are compared with those of other authors.
Analysis of experimental factors in elastic–plastic small specimen mixed‐mode I‐II fracture mechanical testing
Authors: Laukkanen A.
Published: March 2003

The quality of experimental fracture resistance testing results in mixed‐mode I‐II loading is more than questionable in several cases. This study describes efforts to gain consistent results with respect to mixed‐mode I‐II fracture resistance curve determination when working with elastic–plastic materials. The entire mixed‐mode I‐II field is evaluated, i.e. both numerical and experimental factors are considered the focus being on the asymmetric four‐point bend set‐up. Several error prone features are presented, and minimization of their effects on quantitative fracture resistance assessment considered. The results indicate that through a careful evaluation of the stages in experimental testing and numerical analysis valid, material characterizing, fracture toughness results can be obtained.
Improving the fatigue performance of fillet weld terminations
Authors: Dimitrakis S. D. , Lawrence F. V.
Published: March 2003

A specially designed stress‐concentration‐reducing part was incorporated in the wrap‐around welds at the ends of fillet‐welded longitudinal attachments, that is, at fillet weld terminations − ubiquitous weld details having a notoriously poor fatigue resistance. The incorporation of this part at the terminations of the fillet‐welds substantially decreased the weld toe stresses in those locations where fatigue cracks customarily start, reduced weld toe residual stresses and promoted increases in the weld‐toe notch‐root radius. In the long‐life regime, the incorporation of these small, added parts increased weldment fatigue life by 300% and fatigue strength by 30%. It was found that the full benefit of the added part could only be achieved when welding processes were employed that avoided the production of cold‐lap weld‐toe defects.
Effect of Lüders strain on engineering crack opening displacement estimations for leak‐before‐break analysis: finite element study
Authors: Kim Y.‐J. , Huh N.‐S. , Kim Y.‐J.
Published: March 2003

As a companion paper to our previous paper [Fatigue Fract. Engng Mater. Struct. 24, 243–254], this note provides further validation on the engineering crack opening displacement (COD) estimation equation based on the enhanced reference stress method against three‐dimensional, elastic–plastic finite element (FE) results using actual tensile data of three typical ferritic steels exhibiting a wide range of Lüders strain. Furthermore, the resulting FE results are also compared with the GE/EPRI COD predictions. It is found that the proposed enhanced reference stress method gives overall more accurate and robust COD results than the GE/EPRI method, compared with the FE results.
Mixed‐mode crack growth from an unusual source
Authors: Tong J.
Published: March 2003

Out‐of‐plane crack growths were observed in compact tension specimens under static and quasi‐static loading conditions at 650 °C in a nickel based alloy U720Li. The apparent mixed‐mode crack growth behaviour may be explained based on a stability argument. The actual occurrence of the unstable crack growth may depend also on other factors such as the crack growth mechanism, grain size and loading mode.
The fretting fatigue limit based on local stress at the contact edge
Authors: Kondo Y. , Bodai M.
Published: March 2003

It is well known that fretting fatigue is affected by various factors such as contact pressure, relative slip, contact length, specimen size, loading type and so on. In this study, the reason why these factors affect fretting fatigue was investigated on the basis of the stress distribution near the contact edge. The local stress distribution near the contact edge was experimentally measured using a small multi‐element stress concentration gauge. It was shown that the magnitude of the stress concentration at the contact edge varied significantly depending on these factors. It was found that the S–N curve was expressed uniquely on the basis of the local stress amplitude at the contact edge
High temperature fatigue of the nickel‐base single‐crystal superalloy CMSX‐10
Authors: Ohtani R. , Tada N. , Shibata M. , Taniyama S.
Published: March 2003

Push–pull fatigue tests were conducted under a sinusoidal stress waveform with a frequency of 1 Hz and a trapezoidal one with a hold time in both tension and compression at 300 MPa‐amplitude. Tests were conducted at a temperature of 1273 K using smooth bar specimens of the nickel‐base single‐crystal superalloy CMSX‐10. Small cracks were observed on the surface of the interrupted specimens by means of optical and scanning electron microscopes and their number and length were measured. The fatigue behaviour was characterized as follows: (1) A number of small cracks were initiated at a relatively early stage on the grain boundaries of the surface oxide which were perpendicularly to the tensile stress axis direction. (2) Some of these cracks grew inside and reached the base metal. Their growth brought about final fracture of the specimen. (3) The creep strain during the stress hold period accelerated the growth rate of the small cracks and shortened the fatigue life.
Determination of the opening load for a growing fatigue crack: evaluation of experimental data reduction techniques and analytical models
Authors: Blandford R. S. , Daniewicz S. R. , Skinner J. D.
Published: March 2003

In metallic materials, growing cracks will remain closed or partially closed for a portion of the applied cyclic load as a consequence of plastically deformed material left in the wake of a growing crack, surface roughness along the crack surfaces, or corrosion debris. Proper characterization of this crack closure and the subsequent opening load is required for accurate prediction of crack growth. In the laboratory, global load–displacement data are commonly used in conjunction with a data reduction technique to estimate the opening load for a growing crack. Different data reduction techniques will be compared, and the influence of data smoothing will be demonstrated, using AA 7075‐T651 specimens tested under constant amplitude cyclic loading with load ratios R = 0.1, 0.2, and 0.3. The ratio of maximum stress intensity factor to plane strain fracture toughness was approximately Kmax /KIc = 0.5. The measured crack opening loads are also compared with predictions obtained from two different strip‐yield models and three‐dimensional elastic–plastic finite element analyses. Results show the necessity of using smoothed data, and the poor behaviour of the compliance offset data reduction technique, when analysing high load ratio data. A modification to this technique is proposed which improves crack opening load estimates. Overall, the analytical model predictions compare well with the experimental results; especially those results generated using the modified compliance offset technique.
Tensile and compressive damage coupling for fully‐reversed bending fatigue of fibre‐reinforced composites
Authors: Van Paepegem W. , Degrieck J.
Published: March 2003

ABSTRACT Due to their high specific stiffness and strength, fibre‐reinforced composite materials are winning through in a wide range of applications in automotive, naval and aerospace industry. Their design for fatigue is a complicated problem and a large research effort is being spent on it today. However there is still a need for extensive experimental testing or large safety factors to be adopted, because numerical simulations of the fatigue damage behaviour of fibre‐reinforced composites are often found to be unreliable. This is due to the limited applicability of the theoretical models developed so far, compared to the complex multi‐axial fatigue loadings that composite components often have to sustain in in‐service loading conditions.

In this paper a new phenomenological fatigue model is presented. It is basically a residual stiffness model, but through an appropriate choice of the stress measure, the residual strength and thus final failure can be predicted as well. Two coupled growth rate equations for tensile and compressive damage describe the damage growth under tension–compression loading conditions and provide a much more general approach than the use of the stress ratio R. The model has been applied to fully‐reversed bending of plain woven glass/epoxy specimens. Stress redistributions and the three stages of stiffness degradation (sharp initial decline – gradual deterioration – final failure) could be simulated satisfactorily.
Fatigue notch sensitivity of steel blunt‐notched specimens
Authors: CHAPETTI M. D. , TAGAWA T. , MIYATA T.
Published: March 2003

The notch sensitivity of three steels with similar plain fatigue limits was analysed and modelled. The analysis was made by using a model previously derived which estimated the fatigue limit of blunt notched components by means of the parameter ktd defined as the stress concentration introduced by the notch at a distance d from the notch root surface equal to the distance between microstructural barriers. The analyses show how the first two or three microstructural barriers define the fatigue limit and the fatigue notch sensitivity of blunt notched specimens.
Fatigue strength of shot‐peened nitrided steel: optimization of process parameters by means of design of the experiment
Authors: Croccolo D. , Cristofolini L. , Bandini M. , Freddi A.
Published: March 2003

ABSTRACT There is a general interest in increasing the fatigue strength of materials. Shot‐peening and nitriding are the two processes commonly used in order to increase the fatigue strength of steel‐notched components. These two processes are often used separately. The effect of a combination of both processes has not been thoroughly investigated so far. The purpose of the present investigation was two‐fold: first, the authors verified whether further improvements can be achieved by a combination of the two treatments; second, the optimal process parameters were determined in order to obtain the maximal increase in fatigue strength. Fatigue tests were conducted on unnotched and notched nitrided and shot‐peened 32CrMoV13 steel specimens. Several process variables were tested. Tests were designed based on the criteria of the Design of the Experiment (DOE). Three‐level experiments were used in order to determine the optimal set of process parameters. It was found that the combination of nitriding and shot‐peening could be applied successfully in order to increase the fatigue limit when extreme performance is sought in notched components.
Prediction of fatigue crack growth path in mechanical joints using a weight function approach
Authors: HEO S. P. , YANG W. H.
Published: March 2003

Cracks often initiate from the mechanical joints which are widely used in structural components. It has been reported that cracks in mechanical joints are under mixed‐mode condition and there is a critical angle at which mode I stress intensity factor becomes maximum. The crack propagates in an arbitrary direction and the prediction of fatigue crack growth path is needed to provide against crack propagation and examine safety. In this study, mixed‐mode fatigue crack growth tests are performed for horizontal and critical inclined cracks in mechanical joints. Fatigue crack growth paths are predicted using a weight function approach and maximum tangential stress criterion.
Fracture assessment of a clad steel using various SINTAP defect assessment procedure levels
Authors: MOTARJEMI A. K. , KOÇAK M.
Published: March 2003

In many critical industries such as nuclear, chemical and petrochemical industries, bi‐material components in the form of clad plates are used due to their superior environmental and mechanical properties. During the service life of these bi‐material components, cracks or crack‐like defects may develop in the clad layer and penetrate into the substrate. The assessment of the integrity of such a cracked as well as complex structure would be an important task. Hence, this study is aimed at applying the recently developed European Structural Integrity Assessment Procedure (SINTAP) to a through thickness centre cracked clad steel wide plate to validate the procedure for this type of bi‐material structure. Based on the available input data, various assessment levels as well as two different assessment routes, namely crack driving force (CDF) and failure assessment diagram (FAD), can be used for predicting the failure loads. In principle both routes should provide similar results and this has been verified by having very similar results for both SINTAP routes. Furthermore, the degree of conservatism has been reduced by using higher analysis levels of SINTAP.
Near threshold fatigue crack growth versus long finite life
Authors: PARIS P. C. , TADA H.
Published: March 2003

ABSTRACT A brief review of the discovery of the fatigue crack growth threshold is provided with a discussion of the main variables, Kmax and ΔK, which control the threshold over the low and high load ratio ranges, respectively. The significant effect on near threshold growth rates as illustrated by Donald are shown, for an example the aluminium alloy, 2324‐T39. Attention is then turned to the ‘partial closure model’ as a means of correlating near threshold fatigue crack growth rates. This seems to be the most promising model with a physical basis. For this reason, the discussion goes on to present a new theoretical analysis of the load displacement record characteristics, which should accompany ‘partial closure’ of fatigue cracks. In addition it is concluded that secondary stress effects should be explored for near threshold fatigue crack growth rates.
Characteristic S–N properties of high‐carbon–chromium‐bearing steel under axial loading in long‐life fatigue
Authors: SAKAI T. , SATO Y. , OGUMA N.
Published: March 2003

ABSTRACT Owing to difficult economical conditions, machines and structures often have to be used beyond the design lifetime. In this study, fatigue properties of a bearing steel in the long‐life region were experimentally examined under cyclic axial loading. The complicated S–N behaviour was well explained as a combination of S–N curves for surface‐induced fracture and interior inclusion‐induced fracture. Fish‐eye marks were always observed on the fracture surfaces of specimens, which failed in the latter fracture mode, and an inclusion was found at the center of the fish‐eye. Finally, it was found that the fatigue fracture of this steel in the long‐life region occurred through the following three processes: (i) formation of the characteristic area as a fine granular area (FGA), (ii) crack propagation to form the fish‐eye and (iii) rapid crack propagation to cause the catastrophic fracture.
Fatigue crack propagation prediction by cyclic plasticity damage accumulation models
Authors: DURÁN J. A. R. , CASTRO J. T. P. , FILHO J. C. P.
Published: March 2003

Different analytical models of damage accumulation by cyclic plasticity have been developed to predict fatigue crack growth from monotonic, cyclic, fracture toughness and crack propagation threshold properties. The models' development logic is condensed as a flowchart, which emphasizes, in a clear and easily comprehensive way, all the required modeling steps. 1020 and API 5L X60 steels and 7075‐T6 aluminum alloy were used in the experimental verification of the models. Samples were extracted from materials of the same heat, in order to have a reliable comparison. The experimental results are better predicted by the models that use the plastic part of Coffin–Manson's equation to calculate the fatigue life of small volume elements ahead of the crack tip, and expressions of the HRR type to represent the elastic–plastic strain amplitude in the cyclic plastic zone.
Drugs and parasites: global experiments in life history evolution?
Authors: Skorping Arne , Read Andrew F.
Published: March 2003

Recent work has shown that the evolution of Drosophila melanogaster resistance to attack by the parasitoid Asobara tabida is constrained by a trade‐off with larval competitive ability. However, there are two very important questions that need to be answered. First, is this a general cost, or is it parasitoid specific? Second, does a selected increase in immune response against one parasitoid species result in a correlated change in resistance to other parasitoid species? The answers to both questions will influence the coevolutionary dynamics of these species, and also may have a previously unconsidered, yet important, influence on community structure.