Development of efficient modelling strategy for air and contained blast loading
Internal blast loading occurs in structure, when detonation of the explosive takes place inside. R&D efforts on computation of the blast pressures due to such loading are not adequate and therefore, the behaviour of structures due to shock loading is not well understood. A procedure was developed to generate pressure time histories for finite elements due to internal blast considering multiple reflections of blast loads and gas pressure loading. This facilitates assessment of damage of the structures due to blast. The procedure was used for damage assessment caused by impact and blast due to impact of Brahmos missile on a warship.
- Efficient modelling strategy useful in finite element analysis
- Formulation of a simplified approach for blast analysis of laced reinforced concrete (LRC) structures
Laced steel-concrete composite (LSCC) system for blast resistant structures
Through continuous research CSIR–SERC has also developed an alternative structural system, Laced Steel-Concrete Composite (LSCC) for blast-resistant structures. LSCC system comprises of thin steel cover plates provided with apertures / perforations, through which reinforcements in the form of lacings are introduced and held in position with the help of transverse / cross rods, after which concrete is filled in between the cover plates. The cover plates also provide integrity to the in-fill concrete even at large deformations.
Salient aspects / advantages of the LSCC system that makes it suitable for the purpose are
- Sufficiently large ductility / rotational capacity – nearly twice the support rotation compared to the steel-concrete composite beams made with conventional connectors
- Absence of welding – elimination of weak points in the structure
- Partially factory-made – possible for rapid installation and control on workmanship
Impact resistant engineered composite panels
Development of suitable protective measures against high velocity impact by short projectiles is a challenging problem and the solution required multidisciplinary approach. Efforts were directed to make use of steel fibre reinforced cementitious composite (SFRCC) material to design impact resistant panels. Extensive experiments supported by numerical simulations were carried out to arrive at safe configurations for high velocity impact resistant SFRCC panels. Subsequently, in-service field performance of SFRCC panels were also undertaken by subjecting them to impact by 5.56 mm and 7.62 mm caliber bullets fired at practicing ranges.
The highlights of the study are:
- Design charts for impact-resistant SFRCC panels for a given fibre volume fraction against a given caliber projectile
- Reliable solution for protection against ballistic impact by short projectiles
Layered armour components for improved penetration resistance
Advanced research was conducted to develop light weight ceramic/metal composite armours for protection against 7.62 mm armour piercing (AP) projectiles. Refined finite element investigations were carried out to simulate the high velocity impact experiments conducted on ceramic/metal composite panel. Critical predictions were made to decide on the ceramic tile size and layout besides the thickness of adhesive layer used to bond the tile and back plate towards improving the impact performance of the composite panel
The findings are directly useful for designing ceramic / metal armour for protection of critical resources against impact by short projectiles