MUSEUM FOR SOCIETY: EXPERIENCE OF NATIONAL MUSEUM OF EDUCATION IN GABROVO

The direct didactic interpretation of the educational activity of museums has exhausted itself, therefore these cultural institutions should turn to more current methods of promotion of material and non-material heritage along with the tradition forms of activity. The purpose of the research is to establish and analyse the possibilities of museums in terms of public education, making use of the modern technologies. Methods: theoretical literature analysis, collaborative field research, case analysis.The National Museum of Education of Bulgaria in Gabrovo is famous for its artefacts, which characterise the historical development of education in Bulgaria since the 9th century. Therefore this museum is unique in Europe. As a result of the digitization of the museum’s collection it can offer extensive information opportunities and tools to the visitors and users of the museum. According to the legislative changes of 2016, the functions of the National Museum of Education are also expanded, and it becomes a special link of support in the education system of Bulgaria, developing the Centre for Study Visualisation. An innovative element of the museum’s activity is the professional development and dissemination of study visualisation for the purpose of enriching the choice of teaching aids (education films, multimedia presentations, tables and schemes, exhibitions) for use in the study process at general education establishments. The development of such planned, coordinated, state financed and corresponding to the demand study visualisations is an example of good practice of the contribution of the National Museum of Education in public education and it creates bases for adopting the positive experience in other countries. 

Modelling of the low-impulse blast behaviour of fibre–metal laminates based on different aluminium alloys

A parametric study has been undertaken in order to investigate the influence of the properties of the aluminium alloy on the blast response of fibre–metal laminates (FMLs). The finite element (FE) models have been developed and validated using experimental data from tests on FMLs based on a 2024-O aluminium alloy and a woven glass–fibre/polypropylene composite (GFPP). A vectorized user material subroutine (VUMAT) was employed to define Hashin’s 3D rate-dependant damage constitutive model of the GFPP. Using the validated models, a parametric study has been carried out to investigate the blast resistance of FML panels based on the four aluminium alloys, namely 2024-O, 2024-T3, 6061-T6 and 7075-T6. It has been shown that there is an approximation linear relationship between the dimensionless back face displacement and the dimensionless impulse for all aluminium alloys investigated here. It has also shown that the residual displacement of back surface of the FML panels and the internal debonding are dependent on the yield strength of the aluminium alloy

DETERMINATION OF WATER RESOURCES IN RIVERS IN THE BULGARIAN BASINS OF THE LOWER DANUBE

Object of the study is surface water bodies from category “rivers” according to Water Framework Directive 2000/60/ЕС. Surface water assessment is important for number of activities such as: water management in the country, making reports to international agencies, determining the change of the resources in the light of upcoming climate changes. The determination of water resources is based on information of hydrometric stations from the monitoring network system in the National Institute of Meteorology and Hydrology — Bulgarian Academy of Sciences (NIMH-BAS) in which real ongoing and available water flows that are subject of management are registered. In the study a technology for surface water bodies in the Bulgarian basins of the lower Danube is applied which has been developed in the frame of cooperative project together with the Ministry of Environment and Water. This is absolutely true for the Bulgarian section of the Danube River basin which is expressed in big number and variety of hydrological homogeneous sections. The river flow is characterized with annual and inter-annual variability determined by climatic factors and anthropogenic influences. The main obtained results of the present hydrologic studies are the usage of transferred information from gauged to ungauged watersheds and the estimation of the surface water bodies’ resources using original regression relationships based on multiannual hydrological information from the NIMH-BAS monitoring network. The relationships delineate the hydrological homogeneous areas with similar conditions of flow formation. The estimated resources have significant usefulness for all State institutions managing the water in the Danube basin and have already been introduced in the operative and management practice

Low-impulse blast behaviour of fibre-metal laminates

This paper presents three dimensional (3D) finite element (FE) models of the low-impulse localised blast loading response of fibre-metal laminates (FMLs) based on an 2024-O aluminium alloy and a woven glass-fibre/polypropylene composite (GFPP). A vectorized user material subroutine (VUMAT) is developed to define the mechanical constitutive behaviour and Hashin’s 3D failure criteria incorporating strain-rate effects in the GFPP. In order to apply localised blast loading, a user subroutine VDLOAD is used to model the pressure distribution over the exposed area of the plate. These subroutines are implemented into the commercial finite element code ABAQUS/Explicit to model the deformation and failure mechanisms in FMLs. The FE models consider FMLs based on various stacking configurations. Both the transient and permanent displacements of the laminates are investigated. Good correlation is obtained between the measured experimental and numerical displacements, the panel deformations and failure modes. By using the validated models, parametric studies can be carried out to optimise the blast resistance of FMLs based on a range of stacking sequences and layer thicknesses

Rubber Impact on 3D Textile Composites

A low velocity impact study of aircraft tire rubber on 3D textile-reinforced composite plates was performed experimentally and numerically. In contrast to regular unidirectional composite laminates, no delaminations occur in such a 3D textile composite. Yarn decohesions, matrix cracks and yarn ruptures have been identified as the major damage mechanisms under impact load. An increase in the number of 3D warp yarns is proposed to improve the impact damage resistance. The characteristic of a rubber impact is the high amount of elastic energy stored in the impactor during impact, which was more than 90% of the initial kinetic energy. This large geometrical deformation of the rubber during impact leads to a less localised loading of the target structure and poses great challenges for the numerical modelling. A hyperelastic Mooney-Rivlin constitutive law was used in Abaqus/Explicit based on a step-by-step validation with static rubber compression tests and low velocity impact tests on aluminium plates. Simulation models of the textile weave were developed on the meso- and macro-scale. The final correlation between impact simulation results on 3D textile-reinforced composite plates and impact test data was promising, highlighting the potential of such numerical simulation tools

Dynamic compression of foam supported plates impacted by high velocity soil

The response of back-supported buffer plates comprising a solid face sheet and foam core backing impacted by a column of high velocity particles (sand slug) is investigated via a lumped parameter model and coupled discrete/continuum simulations. The buffer plate is either resting (unattached) or attached to a rigid stationary foundation. The lumped parameter model is used to construct maps of the regimes of behaviour with axes of the ratio of the height of the sand slug to core thickness and the normalised core strength. Four regimes of behaviour are identified based on whether the core compression ends prior to the densification of the sand slug or vice versa. Coupled discrete/continuum simulations are also reported and compared with the lumped parameter model. While the model predicted regimes of behaviour are in excellent agreement with numerical simulations, the lumped parameter model is unable to predict the momentum transmitted to the supports as it neglects the role of elasticity in both the buffer plate and the sand slug. The numerical calculations show that the momentum transfer is minimised for intermediate values of the core strength when the so-called “soft-catch” mechanism is at play. In this regime the bounce-back of the sand slug is minimised which reduces the momentum transfer. For high values of the core strength, the response of the buffer plate resembles a rigid plate with nearly no impulse mitigation while at low values of core strength, a slap event occurs when the face sheet impinges against the foundation due to full densification of the foam core. This slap event results in a significant enhancement of the momentum transfer to the foundation. The results demonstrate that appropriately designed buffer plates have potential as impulse mitigators in landmine loading situations