Parametric study of honeycomb composite structure using open source finite element software

This paper deals with the parametric optimisation of a simply supported sandwich panel made of honeycomb composite structure using sequential quadratic programming SQP. The panel consists of aluminum honeycomb sandwiched between two orthotropic fiberglass faces. The parameters studied are fibreglass thickness, tf, honeycomb height, h, and honeycomb wall thickness, tc. The objective was to minimise weight to bending stiffness ratio by using the nonlinear MATLAB function fmincon, considering the maximum central displacement and intercellular buckling as the constraints. Following this, a static structural analysis was conducted on the optimised structure using the open source finite element solver CalculiX and Salome Platform software for preprocessing. The utmost displacement of the honeycomb panel was desirably less than the serviceability limit. Preliminary results show that composite honeycomb structures can be optimised yielding low weight to bending stiffness ratio using SQP method and CalculiX for design evaluation

Acoustic emission wave propagation in honeycomb sandwich panel structures

This paper studies acoustic emission (AE) wave propagation in a glass fibre aluminium honeycomb sandwich panel (HSP). Of particular novelty is the quantification of the through-thickness propagation of AE from one surface of the HSP to the other, which is a real-world monitoring consideration for applications where AE instrumentation is only be permissible on one surface, i.e. aerofoils. Complexity was introduced to the specimens in stages to enable a thorough understanding; first investigating propagation in a large glass fibre laminated plate (GFLP) alone; then in bespoke sandwich specimens with a limited number of honeycomb cells; and, finally, in a large HSP. The results of this paper demonstrate that, whilst some energy is transmitted through the honeycomb core, AE propagating in an HSP becomes bound in the outer plates. Despite this, propagation in these outer plates differs to that in an equivalent plate of the same material in isolation due to the complex interactions with the structural elements of the HSP. Further, propagation of AE transmitted from one surface to the other was quantified for the first time, giving insight into expected attenuation rates and characteristics for practical applications

Birth Defects in Gaza: Prevalence, Types, Familiarity and Correlation with Environmental Factors

This is the first report of registration at birth, and of incidence of major structural birth defects (BD) obtained in Gaza at Al Shifa Hospital, where 28% of total births in Gaza Strip occur. Doctors registered 4,027 deliveries, with a protocol comprehensive of clinical, demographic, kin and environmental questions. Prevalence of BD is 14/1,000, without association with intermarriage or gender of the child. Prevalence of late miscarriages and still births are respectively 23.3/1,000 and 7.4/1,000, and of premature births 19.6/1,000. Couples with a BD child have about 10 times higher frequency of recurrence of a BD in their progeny than those with normal children, but none of their 694 siblings and only 10/1,000 of their 1,423 progeny had BD, similar to the frequency in general population. These data suggest occurrence of novel genetic and epigenetic events in determination of BD. Children with BD were born with higher frequency (p < 0 001) in families where one or both parents were under “white phosphorus” attack, that in the general population. Bombing of the family home and removal of the rubble were also frequently reported by couples with BD occurrence. These data suggests a causative/favoring role of acute exposure of parents to the weapons-associated contaminants, and/or of their chronic exposure from their persistence in the environment on the embryonic development of their children