Structural Behavior of Ferrocement Concrete Plates Subjected to Flexural and Dynamic Loadings

Ferrocement is one of the structural materials, widely used due to its advantages from its particular behavior such as mechanical properties, and impact strength. This paper deals with the impact studies and energy absorption properties of ferrocement slabs. For these studies, 11 different ferrocement slabs of size 50 mm X 500 mm X 25 mm were cast with alteration in the combinations of mesh layers and test results are analyzed to find the different crack patterns .The test specimens were loaded by 3.10 kg under its height 1.20 m in the center of plates. The ferrocement plates were divided into 4 groups reinforced with steel mesh, steel mesh with steel bars, percentage of rubber and fiber. The impact energy at initial cracking stage and at failure was determined for all the slabs. Results of reinforced ferrocement plates emphasized that increasing the number of the steel mesh layers in the ferrocement forms increases the first cracking load, ultimate load and energy absorption. Using steel bars with steel meshes led to higher energy absorption than that obtained when using mild steel bars only. Using rubber and fiber achieved high impact energy.

Microstructure and Mechanical Properties of Welded Joints in Austenitic Steel TP347HFG after Operation

The analysis involved a similar welded joint made of steel TP347HFG after operation at a temperature of 580°C. Tests revealed that the primary mechanisms responsible for the degradation of the microstructure in all areas of the joint subjected to analysis were precipitation processes within the grains and along the grain boundaries. The grain boundaries contained two morphologies forming a continuous lattice. Precipitation processes resulted in the high tensile strength of the joint and high hardness within the weld face area. After operation, the test joint was characterised by relatively high impact energy, which could be attributed to the fine-grained microstructure and the presence of numerous annealing twins.

Experimental investigation of impact of long rod eroding projectiles against rolled homogeneous armour

Long rod eroding penetrators exhibit hydrodynamic behaviour upon impact against the target plates. An experimental study was carried out to investigate the factors affecting the penetration of tungsten alloy rods against rolled homogenous armour at ordnance velocities. Experiments were carried out for range of projectile length to diameter ratios to determine the penetration efficiency of the projectile, where the projectile penetration efficiency is the penetration depth per unit projectile length. Analytical Alekseevski–Tate model was implemented to predict the penetration depth across the length to diameter range and the results were compared with the experimental data. The tungsten percentage of the projectile material was also varied to change its mechanical properties and thus observe the effect of the same on the penetration depth. The experimental results showed a linear relationship between the penetration efficiency and the length to diameter ratio across the considered range of length to diameter ratios. The Alekseevski–Tate model predictions were not consistent across as the model does not consider the effect of length to diameter ratio. The projectiles with high impact energy were able to perforate the target plate.

Effect of fiber architecture on the residual strength of laminate glass fiber-reinforced polymer composites after impact

Glass fiber-reinforced polymer (GFRP) composites are widely applied in automotive and shipbuilding industry. However, impact damage is unavoidable to the composites during production or service, and the evaluation of performance degradation after impact is necessary. The architecture of the fiber preform shows significant influence on the impact damage behavior of GFRP. The present work focused on the influence of preform structure on damage evolution and residual load-bearing capability of the composites. The microstructure and the residual strength after the impact of GFRP with plain-weave preform structure and cross-ply preform structure have been investigated, respectively. The low velocity impact primarily caused matrix cracking and delamination, but unobvious fiber failure to GFRP. More impact-damaged plies were detected in cross-ply composites than plain-weave composites after impact. It indicated that plain-weave preform structure owes better impact damage shielding capability. However, the GFRP with plain-weave preform structure exhibited better impact resistant ability under low impact energy but less residual strength under high impact energy, compared with the GFRP with cross-ply preform structure. The interaction between the warp and weft fibers made the plain-weave composites absorbing more energy in a single ply, which was the reason for the plain-weave composites to exhibit excellent damage shielding performance but poor residual strength under high impact energy.

Impact and Hardness Characteristics of Cfrp-Kenaf-Abaca Fiber Composites

Industries call for green materials which will supervene upon the ancient materials through virtue of their high strength to weight ratio. Composite substances of herbal behavior satisfy the above desires with a aggregate of one or more materials. In this paper, the combination of herbal fibers mainly Abaca and Kenaf are taken as reinforcement and CFRP as matrix medium. Here the Composite is laminated using Compression Moulding Method. Impact and Hardness Tests has been done to determine the mechanical behavior of the composite laminate. It has been concluded that the Category II suggests better mechanical property when compared to the other two categories and observed Impact energy of 6 Joule and Hardness of 108 HRB respectively. Scanning Electron Microscope was done to observe the internal mechanical behaviour of the composite laminate. From SEM it is noted that minimum propagation of crack and voids present in the composite laminate. It has been observed that this hybrid composite laminate can be implemented wherever high impact energy demands.

Wear behaviors of WC and TiC on co matrix composites under three-body impact abrasive wear condition

Purpose The purpose of this paper is to investigate the tribological properties of the WC/TiC-Co substrate under different loading conditions under three impact abrasive wear conditions. Design/methodology/approach The three body collisional wear behavior of Co alloy with WC and TiC at three impact energy was studied from 1 to 3 J. Meanwhile, the microstructure, hardness, phase transformation and wear behavior of these specimens were investigated by scanning electron microscopy, Rockwell hardness (HRV), EDS and impact wear tester. The resulting wear rate was quantified by electronic balance measurements under different pressures. Findings The specific wear rate increases with the increase of the nonlinearity of the impact energy and the increase in the content of WC or TiC. The effect of TiC on wear rate is greater than that of WC, but the hardness is smaller. The wear characteristics of the samples are mainly characterized by three kinds of behavior, such as cutting wear, abrasive wear and strain fatigue wear. The WC-Co with fewer TiC samples suffered heavier abrasive wear than the more TiC samples under both low and high impact energy and underwent fewer strain fatigue wears under high impact energy. Originality/value The experimental results show that the wear resistance of the Co alloy is improved effectively and the excellent impact wear performance is achieved. The results can be used in cutting tools such as coal mine cutting machines or other fields.

Self-woven nanofibrillar PEDOT mats for impact-resistant supercapacitors

Horizontally directed nanofibrillar PEDOT mats bearing high impact energy densities are fabricated as electrodes for impact-resistant flexible supercapacitors.

Additive Manufacturing Enabled by Electrospinning for Tougher Bio-Inspired Materials

Nature has taught us fascinating strategies to design materials such that they exhibit superior and novel properties. Shells of mantis club have protein fibres arranged in a 3D helicoidal architecture that give them remarkable strength and toughness, enabling them to absorb high-impact energy. This complex architecture is now possible to replicate with the recent advances in additive manufacturing. In this paper, we used melt electrospinning to fabricate 3D polycaprolactone (PCL) fibrous design to mimic the natural helicoidal structures found in the shells of the mantis shrimp’s dactyl club. To improve the tensile deformation behavior of the structures, the surface of each layer of the samples were treated with carboxyl and amino groups. The toughness of the surface-treated helicoidal sample was found to be two times higher than the surface-treated unidirectional sample and five times higher than the helicoidal sample without surface treatment. Free amino groups (NH2) were introduced on the surface of the fibres and membrane via surface treatment to increase the interaction and adhesion among the different layers of membranes. We believe that this represents a preliminary feasibility in our attempt to mimic the 3D helicoidal architectures at small scales, and we still have room to improve further using even smaller fibre sizes of the modeled architectures. These lightweight synthetic analogue materials enabled by electrospinning as an additive manufacturing methodology would potentially display superior structural properties and functionalities such as high strength and extreme toughness.