Computation of Onset and Growth of Delamination in Double Cantilever beam Specimens Subjected to Fatigue Loading

In this article, the delamination onset and growth behavior of double cantilever beam (DCB) specimens has been presented. The modeling of a debonded region using master and slave surface technique for DCB specimens is done in ABAQUS CAE. The analysis of DCB specimens comprising of fatigue cyclic load has been done in ABAQUS. An onset and Paris delamination growth regimes are plotted. The growth regime being linear in log-log scale, the prediction of constants of this regime has been obtained using the polyfit command in the MATLAB environment. To obtain these constants has been explained in this article. Comparison of experimental and analytical results is shown for delamination growth. The strain energy release rate values for threshold and critical are indicated on the graphs. The number of cycles for delamination onset and growth has been tabulated for various load cases.Defence Science Journal, Vol. 64, No. 4, July 2014, pp. 400-405, DOI:http://dx.doi.org/10.14429/dsj.64.4069

THERMAL CONDUCTIVITY ENHANCEMENT OF SILICON INSERTED HYBRID COMPOSITE MATERIALS

In this investigation thermal conductivity test was carried out to the prepared specimen of silicon inserted hybrid composite material (on silicon inserted glass –fiber chop strand and other silicon inserted glass –fiber 900woven). The specimens were prepared by hand layup followed by compression molding method. The apparatus consist of two copper plates and one specimen together clamped on both sides using bolts and nuts. On one side of the copper plate a heater is fitted. End losses from the plates are minimized by providing thick insulation all around to ensure unidirectional heat flow. A dimmer stat is provided for varying the input to the heater and measurements of input is carried out by Voltmeter. Thermocouples are bounded in mica are embedded between the interface of the copper materials and the specimen of silicon inserted hybrid composite material, to read the temperature at the surface

Crack growth simulation of stiffened fuselage panels using XFEM techniques

418-428In this paper, crack growth modelling and simulation of stiffened and un-stiffened fuselage panels has been presented using commercially available finite element software package. Computation of stress intensity factor for a single edge notch specimen has been computed using extended finite element method (XFEM), FEM and compared with the analytical solution. The geometric nonlinear and elastic-plastic (material nonlinear) analysis has been performed on a specimen, stiffened and un-stiffened fuselage panels. XFEM techniques like cohesive segment and XFEM based LEFM using virtual crack closure technique (VCCT) are used for crack growth analysis. Various crack domain selection and parametric studies of stiffener thickness are presented. It is observed from the numerical analyses that the stiffened panels have about 20% higher yield strength compared to the un-stiffened panel. </span

A REVIEW ON THERMAL PROPERTIES OF GLASS FIBRE REINFORCED HYBRID POLYMER COMPOSITE MATERIALS

Hybrid Polymer Composites offer new solutions to materials problems; they are currently the focus of research and development areas in all over world. In many common and advanced engineering applications, polymers and their hybrid composites are emerging as variable alternatives to metals and their alloys. Due to different thermal conditions and mechanical loading situations, hybrid composite materials need to be tested intensively. The hybrid composite materials are exposed under different low temperatures and high temperatures at environmental conditions will gives polymeric matrix hybrid composites are susceptible to degradation and material properties changes. Carbon fibre composites are widely used as structural reinforcement materials of buildings, replacing reinforcing bars or concrete which should have excellent mechanical and thermal properties. Hybrid polymer composites with different filler materials will give different thermal property values for variable temperature conditions. This paper presents reviewon thermal properties fibre reinforced hybrid composite materials and came to know that still an abundant scope to do research on study of thermal properties of composite materials by using Silicon, Aluminium oxides, Carbon and Graphite as a filler material of combination of glass fibre and natural fibres. This review study shows that the effect of thermal properties on fibre reinforced hybrid composite materials and hybridization can improve thermal properties

A study on electrical resistance and RSW characterizaton of bimetal wire

The objective of this study is to reduce copper consumption in Solenoid of Circuit breaker by using aluminium with copper technically called copper clad aluminium. Aluminium wires with copper clad are widely used, e.g. in telecommunication, power engineering, electronics as a replacement of traditional applied copper wire. The reason is that the properties of these bimetal wires combine the smaller density and low cost. This study investigates the effect of tripping properties in Circuit breaker thru various magnetic testing methods. Magnetic testing and an experiment verified the tripping threshold depends on the Copper and aluminium combination ratio

Echocardiographic detection of free-floating thrombus in left ventricle during coronary artery bypass grafting

We report an incident of detection of a free-floating thrombus in the left ventricle (LV) using intraoperative two-dimensional (2D) and three-dimensional (3D) transesophageal echocardiography (TEE) during proximal coronary artery bypass graft anastomosis. A 58-year-old man presented to us with a 6-month history of chest pain without any history suggestive of myocardial infarction or transient ischemic attacks. His preoperative echocardiography revealed the systolic dysfunction of LV, mild hypokinesia of basal and mid-anterior wall, and the absence of an aneurysm. He was scheduled for on-pump coronary artery bypass surgery. On intraoperative TEE before establishing cardiopulmonary bypass (CPB), a small immobile mass was found attached to LV apical area. After completion of distal coronary artery grafting, when the aortic cross-clamp was removed, the heart was filled partially and beating spontaneously. TEE examination using 2D mode revealed a free-floating mass in the LV, which was suspected to be a thrombus. Additional navigation using biplane and 3D modes confirmed the presence of the thrombus and distinguished it from papillary muscles and artifact. The surgeon opened the left atrium after re-establishing electromechanical quiescence and removed a thrombus measuring 1.5 cm Χ 1 cm from the LV. The LV mass in the apical region was no longer seen after discontinuation of CPB. Accurate TEE-detection and timely removal of the thrombus averted disastrous embolic complications. Intraoperative 2D and recent biplane and 3D echocardiography modes are useful monitoring tools during the conduct of CPB

Appropriateness of elective percutaneous coronary intervention and impact of government health insurance scheme — A tertiary centre experience from Western India

Background: There is a dearth of data regarding the appropriateness of elective percutaneous coronary intervention (PCI) in a limited-resource country such as India. In an attempt to rationalise the use of PCI, Appropriate Use Criteria (AUC) were developed for cardiovascular care in the USA. In the Indian context, considering the high prevalence of coronary artery disease, the dramatic rise in the number of revascularization procedures and an increasing role of government/private reimbursements, application of AUC could potentially guide policy to optimize the utilization of resources and the benefit-risk ratio for individual patients. Objectives: The study sought to determine the overall and year-wise trends in the appropriateness of elective PCI using the AUC and also understand the impact of the government health insurance scheme (GHIS). Material and Methods: The inpatient records of all patients undergoing elective PCI, at a single large tertiary care centre in Western India, from January 2009 to December 2014 were retrospectively analysed (n=972, 759 males, 213 females) by a neutral observer. The AUC scores and subsequent ranking were calculated using the dedicated web-based software and each PCIwas ranked as either ‘appropriate’, ‘uncertain’ or ‘inappropriate’. Elective PCI performed within a month after the index acute coronary syndrome (ACS) was considered as 'ACS' while applying the AUC. All other indications were considered as 'non-ACS'. Nearly 95% of elective PCI performed after July 2012 were covered under theGHIS and therefore the period January 2009–June 2012 was compared with the July 2012– December 2014 to assess the impact of this scheme. Results: A total of 894 elective PCI (379 and 515 PCI in the ACS setting and non-ACS setting respectively) performed on 857 patients were analysed. The elective PCI performed in the pre-GHIS and GHIS period were 458 and 436 respectively. As per AUC, 352 (39.6 ± 4.4 %) of the overall elective PCI were ranked as ‘appropriate’, while 487 (55.3 ± 4.1 %) cases as ‘uncertain’ and 55 (5.1 ± 0.6 %) cases as ‘inappropriate’. An overall year-wise temporal trend in the proportion of cases in any of the AUC rankings did not show any significant trends(p > 0.05). However, 80.4 ± 7.3 % of elective PCI in the ACS setting were categorised as ‘appropriate’ and 82.6 ± 6.9 % of elective PCI in non-ACS setting were ranked as ‘uncertain’. With state-wide implementation of the GHIS, the total number of elective PCI increased by 50% (436 in the 3½ year pre-GHIS study period as against 458 in the 2½ year GHIS study period). The introduction of GHIS led to a marginal increase (p > 0.05) in the average annual number of elective PCI in non-ACS setting as opposed to a 120% rise in the number of elective PCI done in the ACS setting (p < 0.001) and the delay in performing PCI after coronary angiogram reduced from 55.8 ± 43.6 days to 33 ± 22.9 days (p < 0.01). Also, the ratio of men: women undergoing elective PCI rationalised from 5.4:1 to 2.7:1 (p < 0.001). With the introduction of the GHIS, the share of ‘inappropriate’ elective PCI in the ACS setting increased from 1.34 % to 4.81 % (p =0.065). However, there was also a fall in ‘appropriate’ elective PCI in the non-ACS setting from 15.0 ± 3.2% to 7 ± 1.6% (p < 0.001). Conclusion: On applying the 2012 updated AUC, about 5 % of overall elective PCI were deemed as ‘inappropriate’. About four in every five elective PCI in the non-ACS setting were of ‘uncertain’ appropriateness. The implementation of the GHIS not only significantly reduced the gender bias and delay in seeking interventional coronary care but also led to a significant rise in the proportion of PCI performed in the ACS setting. However, there was also a rise in ‘inappropriate’ PCI in the ACS setting and a significant fall in ‘appropriate’ PCI in the non-ACS setting after introduction of the GHIS.