Wan Fathul Hakim Wan Zamri

BALLISTIC LIMIT OF HIGH-STRENGTH STEEL AND AL7075-T6 MULTI-LAYERED PLATES UNDER 7.62-MM ARMOUR PIERCING PROJECTILE IMPACT

THIS PAPER PRESENTS THE COMPUTATIONAL-BASED BALLISTIC LIMIT OF LAMINATED METAL PANELS COMPRISED OF HIGH STRENGTH STEEL AND ALUMINIUM ALLOY AL7075-T6 PLATE AT DIFFERENT THICKNESS COMBINATIONS TO NECESSITATE THE WEIGHT REDUCTION OF EXISTING ARMOUR STEEL PLATE. THE NUMERICAL MODELS OF MONOLITHIC CONFIGURATION, DOUBLE-LAYERED CONFIGURATION AND TRIPLE-LAYERED CONFIGURATION WERE DEVELOPED USING A COMMERCIAL EXPLICIT FINITE ELEMENT CODE AND WERE IMPACTED BY 7.62 MM ARMOUR PIERCING PROJECTILE AT VELOCITY RANGE OF 900 TO 950 M/S. THE BALLISTIC PERFORMANCE OF EACH CONFIGURATION PLATE IN TERMS OF BALLISTIC LIMIT VELOCITY, PENETRATION PROCESS AND PERMANENT DEFORMATION WAS QUANTIFIED AND CONSIDERED. IT WAS FOUND THAT THE MONOLITHIC PANEL OF HIGH-STRENGTH STEEL HAS THE BEST BALLISTIC PERFORMANCE AMONG ALL PANELS, YET IT HAS NOT CAUSED ANY WEIGHT REDUCTION IN EXISTING ARMOUR PLATE. AS THE WEIGHT REDUCTION WAS INCREASED FROM 20-30%, THE DOUBLE-LAYERED CONFIGURATION PANELS BECAME LESS RESISTANCE TO BALLISTIC IMPACT WHERE ONLY AT 20% AND 23.2% OF WEIGHT REDUCTION PANEL COULD STOP THE 950M/S PROJECTILE. THE TRIPLE-LAYERED CONFIGURATION PANELS WITH SIMILAR AREAL DENSITY PERFORMED MUCH BETTER WHERE ALL PANELS SUBJECTED TO 20-30% WEIGHT REDUCTIONS SUCCESSFULLY STOPPED THE 950 M/S PROJECTILE. THUS, TRIPLE-LAYERED CONFIGURATIONS ARE INTERESTING OPTION IN DESIGNING A PROTECTIVE STRUCTURE WITHOUT SACRIFICING THE PERFORMANCE IN ACHIEVING WEIGHT REDUCTION.

Microscale groove effect on shear strength of epoxy-bonded dissimilar metal plate

Abstract In this study, the shear strengths of Al 7075–HSS adhesive bonded, grooved and smooth plates were investigated. The proven toughness and durability of adhesives have drawn the attention of researchers who want to take advantage of the technology to benefit the development of ballistic resistance sandwich panels. However, the strength of the panel depends on the design of surface topography. Therefore, it is essential to understand the fracture upon loading parallel to the plane of the adhesive bonded metal plates. In this experiment, toughened epoxy was used to bond dissimilar metal plates at 1 mm thickness. The shear tests were performed with a universal-testing machine to identify the maximum fracture loads. The results showed that a shear lap joint specimen with a grooved surface yields a higher strength than a smooth specimen. From the fracture behaviour of all specimens, interfacial failure with some degree of cohesive failure was observed. This indicates that the strength of the adhesive-bonded metal plate driven by a mechanical interlocking effect and mode of failure for thick bondline was the result of interfacial strength rather than adhesive bulk strength. Shear value results and fractography for 1 mm bond thickness provide insights towards steel fibre application in epoxy.

Systematically study on the magnetism and critical behaviour of layered NdMn1.4Cu0.6Si2

The strong dependence of the field-induced on the body-centered tetragonal ThCr2Si2-type and the critical behaviour of magnetic phase transition in NdMn2-xCuxSi2 based compounds guide us to study the substitution Mn (atomic radius = 1.35 A) by Cu (atomic radius = 1.28 A) in layered NdMn1.4Cu0.6Si2 compound. Room temperature x-ray diffraction study indicates clearly that most of the reflections can be identified with ThCr2Si2-type structure with space group I4/mmm. It found lattice parameters a slightly increases and lattice parameter c decrease compare to NdMn2Si2 as indicated the decreasing of volume structure. The Neel temperature TN is found at 340 K while Curie temperature TC found at 75 K respectively. The increasing concentration of Cu in replacement of Mn changes the magnetic phase transition from first order type for NdMn2Si2 to second order type for layered NdMn1.4Cu0.6Si2 compound as been determined by particular the S-shaped nature of the Arrott plot near TC. Our results indicate that the magnetic-field-induced magnetic phase transition plays a critical role on producing large magnetocaloric effect in these systems especially on second order type as the key for further investigation. The critical behaviour analysis in the vicinity of TC demonstrates that the magnetism of the layered NdMn1.4Cu0.6Si2 compound is governed by long range interactions.The strong dependence of the field-induced on the body-centered tetragonal ThCr2Si2-type and the critical behaviour of magnetic phase transition in NdMn2-xCuxSi2 based compounds guide us to study the substitution Mn (atomic radius = 1.35 A) by Cu (atomic radius = 1.28 A) in layered NdMn1.4Cu0.6Si2 compound. Room temperature x-ray diffraction study indicates clearly that most of the reflections can be identified with ThCr2Si2-type structure with space group I4/mmm. It found lattice parameters a slightly increases and lattice parameter c decrease compare to NdMn2Si2 as indicated the decreasing of volume structure. The Neel temperature TN is found at 340 K while Curie temperature TC found at 75 K respectively. The increasing concentration of Cu in replacement of Mn changes the magnetic phase transition from first order type for NdMn2Si2 to second order type for layered NdMn1.4Cu0.6Si2 compound as been determined by particular the S-shaped nature of the Arrott plot near TC. Our results indicate that the magne...