An investigation into the role of school-governing bodies with reference to the Kuyasa Secondary School, King William's Town District

The introduction of school governing bodies provided communities with an opportunity to play a significant role in the organisation and governance of their schools. This involvement of significant stakeholders is purported to oversee that schools offer education of high quality to the learners. However, school governance is a legal responsibility, which requires the skills, knowledge and expertise to ensure that SGB members will be able to fulfil their concomitant legal duties. The aim of the study was to investigate the impact of the SGBs role in school governance in Kuyasa Secondary School, King Williams Town District. The findings revealed that the SGBs knowledge and understanding of their roles and responsibilities, and the type of training they receive have a marked effect on their functionality. There is also a need to recruit SGB members with a particular level of education, knowledge, understanding and expertise to minimise the chances of failure

ANALISI DEL COMPORTAMENTO AD ELEVATO STRAIN RATE DI UNA SCHIUMA METALLICA ALSI7

La capacità di assorbimento di energia delle schiume di alluminio, generalmente caratterizzata da uniforme e basso stress, ne fa un candidato importante in tutte quelle applicazioni in cui si vuole aumentare l’efficienza dell’assorbimento con pesi contenuti. Le schiume di alluminio vengono regolarmente utilizzate in numerosi settori dell’ingegneria e con riferimento alla loro caratterizzazione il comportamento ad alto strain rate merita di essere ulteriormente investigato. In precedenti lavori è stato mostrato come questo tipo di materiale, a causa di disomogeneità locali di fabbricazione, possa presentare differenti proprietà meccaniche e differenti capacità di assorbimento, a seconda della zona da cui i provini vengono estratti. In questo lavoro si valutata la suddetta capacità di assorbimento ad elevata velocità di deformazione, mettendola in relazione con la distribuzione di densità registrata all’interno del lingotto di estrazione dei provini. La lega investigata è una AlSi7; le prove sono state eseguite mediante l’apparato barra di Hopkinson a tensione diretta

Experimental and Numerical Analysis of Pressure Waves Propagation in a Viscoelastic Hopkinson Bar

In this paper, the viscoelastic behaviour of PET is assessed in order to study the wave propagation in long SHPB made of polymeric materials. First, an analytical formulation and a numerical FE model were set up and validated using viscoelastic parameters borrowed from literature. However, for a correct description of the attenuation factor and the complex wave number of the real PET material, the storage and loss moduli as functions of the frequency must be known. For this reason, DTMA tests have been conducted at different temperatures and frequency; the experimental curves have been shifted, extrapolating the storage and loss master functions up to 100 kHz, and used for identifying the stiffness and damping parameters of a generalized Maxwell model. Then, these parameters were implemented into the numerical model for simulating the wave propagation in long bars. The numerical results are compared with the real wave signals measured from experiments performed on a SHPB made of the same PET material

Experimental and numerical characterization of a polymeric Hopkinson bar by DTMA

This paper is focused on the study of wave propagation in long Split-Hopkinson Pressure Bar (SHPB) setups made of polyethylene terephthalate (PET). The first step was the set up and the validation of an analytical formulation and of a FE model based on viscoelastic parameters, borrowed from literature; then, Dynamic-Mechanical Thermal Analysis (DTMA) has been conducted at different temperatures and frequencies, in order to obtain the storage and loss moduli of the real PET, as functions of the frequency. Experimental curves were shifted in order to extrapolate storage and loss master functions up to several kHz and to identify the stiffness and the damping parameters of a generalized Maxwell model. The obtained parameters were used to compute the attenuation factor and the wave number, which allows the analytical investigation of wave propagation in long bars. The proposed characterization method based on DTMA was applied to pressure waves experimentally measured on the SHPB made of PET; results were compared with the well-established “transfer function” method. Finally, an SHPB experiment was simulated using the FE model, in order to assess the impact of the proposed wave propagation analysis on the reconstructed stress–strain curve of a low impedance material