Research shows that mechanical properties of parts produced using fused deposition modeling (FDM)... more Research shows that mechanical properties of parts produced using fused deposition modeling (FDM) are inferior when compared to parts produced using conventional techniques such as injection molding. Efforts have been made in recent years to improve mechanical properties by reinforcing the parts with high strength fibers. This has been achieved by either modifying FDM setups to extrude fibers with thermoplastics and fabricate continuous fiber reinforced thermoplastic composites (CFRTPCs) or employing manual techniques subsequent to part production. Existing CFRTPCs fabrication procedures have limitations of fiber exposure to environment, no direct control method for volume fraction, and poor surface finish. This research work is focused on improving the process of producing CFRTPCs by addressing these limitations using a dual extruder FDM setup. The process developed was tested for its feasibility using Kevlar fiber as reinforcement for commercially available ABS, PLA, PLA-C, and PL...
The International Journal of Acoustics and Vibration
A three-dimensional numerical simulation of the interaction of a surface acoustic wave (SAW) with... more A three-dimensional numerical simulation of the interaction of a surface acoustic wave (SAW) with a droplet of water is carried out. The mixing produced inside the droplet due to the incident with the SAW and the droplet is investigated by undertaking a parametric study, with parameters such as frequency, drop size, and the lateral position of the droplet on the surface of the substrate. The linear relationship between the input voltage and the mixing velocity inside the droplet is obtained with variation of the input voltage of the inter-digital transducer (IDT) of the SAW device within a 10--40 V range. With the variation in frequency, the maximum mixing velocity is observed at 20 MHz and it appears to be independent of the size of the droplet. Varying the substrate material with lead zirconate titanate and lithium niobate produces better mixing. Lithium niobate is preferred due to its availability and cost-effectiveness. A drop of 600 um diameter produces better mixing. The diffe...
Continuous fibre-reinforced composites have significant industrial importance and usage. However,... more Continuous fibre-reinforced composites have significant industrial importance and usage. However, they are limited by design considerations and high-cost manufacturing operations. This article presents a way forward to utilize Fused Deposition Modelling – a 3D printing technique – to manufacture continuous carbon fibre-reinforced thermoplastics. Several parameters including number of reinforced layers, material impact and interlayer gap have been investigated and optimized using response surface method. Successful incorporation of modified novel nozzle design in a dual nozzle setup resulted in the realization of controlled manufacturing of continuously reinforced composites leading to reinforced yet smooth surface finished samples. Several samples were made, and mechanical testing, parameter optimization, strength calculations and fracture analysis were carried out. For polylactic acid (PLA), tensile strength of 112 MPa and flexural strength of 164 MPA were achieved – an almost 3 ti...
Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications
This study investigates ballistic response of a developed perforated armour plate against 12.7 mm... more This study investigates ballistic response of a developed perforated armour plate against 12.7 mm armour piercing tracer projectile. Experimental as well as numerical studies were carried out and the penetration of the projectile through a base aluminium plate was determined with and without the perforated armour plate. The armour piercing projectiles were able to penetrate the base armour plate in successive impacts. However, the combination of the perforated and base armour plates was able to stop the penetration of the armour piercing projectile. A finite element method-based numerical model was developed to investigate the defeating phenomenon of perforated and base armour plate combination. It was observed that the asymmetric impact of the projectile core did not produce large enough bending to fracture the core. However, the high hardness of the developed perforated plate was able to shatter the projectile core in multiple fragments which were then unable to penetrate the base...
Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications
Shaped charges are used in many civilian and military applications. This study focuses on the eff... more Shaped charges are used in many civilian and military applications. This study focuses on the effects of liner material and the type of explosive on the development of shaped charge jet. This was carried out by experimentation and numerical finite element-based modelling. Shaped charges were tested on a steel plate during the experimentation and the experimental data were used to validate the developed numerical model of the shaped charge. A hydrocode-based finite element model was able to predict the perforation and jet formation for the shaped charge, as well as the characteristics of the holes formed in the target plate. Several variations of the numerical model with the change of liner material and the filled explosive showed that the higher explosive resulted in higher velocity jet. The jet formation and velocity of jet were compared to determine the better performing combination of the material and explosive for the given shaped charge geometry. The underlying mechanisms were ...
In recent years, cohesive elements based on the cohesive zone model (CZM) have been increasingly ... more In recent years, cohesive elements based on the cohesive zone model (CZM) have been increasingly used within finite element analyses of adhesively bonded joints to predict failure. The cohesive element approach has advantages over fracture mechanics methods in that an initial crack does not have to be incorporated within the model. It is also capable of modelling crack propagation and representing material damage in a process zone ahead of the crack tip. However, the cohesive element approach requires the placement of special elements along the crack path and is, hence, less suited to situations where the exact crack path is not known a priori. The extended finite element method (XFEM) can be used to represent cracking within a finite element and hence removes the requirement to define crack paths or have an initial crack in the structure. In this article, a hybrid XFEM-cohesive element approach is used to model cracking in the fillet area using XFEM where the crack path is not known and then using cohesive elements to model crack and damage progression along the interface. The approach is applied to the case of an aluminium–epoxy single lap joint and is shown to be highly effective.
Research shows that mechanical properties of parts produced using fused deposition modeling (FDM)... more Research shows that mechanical properties of parts produced using fused deposition modeling (FDM) are inferior when compared to parts produced using conventional techniques such as injection molding. Efforts have been made in recent years to improve mechanical properties by reinforcing the parts with high strength fibers. This has been achieved by either modifying FDM setups to extrude fibers with thermoplastics and fabricate continuous fiber reinforced thermoplastic composites (CFRTPCs) or employing manual techniques subsequent to part production. Existing CFRTPCs fabrication procedures have limitations of fiber exposure to environment, no direct control method for volume fraction, and poor surface finish. This research work is focused on improving the process of producing CFRTPCs by addressing these limitations using a dual extruder FDM setup. The process developed was tested for its feasibility using Kevlar fiber as reinforcement for commercially available ABS, PLA, PLA-C, and PL...
The International Journal of Acoustics and Vibration
A three-dimensional numerical simulation of the interaction of a surface acoustic wave (SAW) with... more A three-dimensional numerical simulation of the interaction of a surface acoustic wave (SAW) with a droplet of water is carried out. The mixing produced inside the droplet due to the incident with the SAW and the droplet is investigated by undertaking a parametric study, with parameters such as frequency, drop size, and the lateral position of the droplet on the surface of the substrate. The linear relationship between the input voltage and the mixing velocity inside the droplet is obtained with variation of the input voltage of the inter-digital transducer (IDT) of the SAW device within a 10--40 V range. With the variation in frequency, the maximum mixing velocity is observed at 20 MHz and it appears to be independent of the size of the droplet. Varying the substrate material with lead zirconate titanate and lithium niobate produces better mixing. Lithium niobate is preferred due to its availability and cost-effectiveness. A drop of 600 um diameter produces better mixing. The diffe...
Continuous fibre-reinforced composites have significant industrial importance and usage. However,... more Continuous fibre-reinforced composites have significant industrial importance and usage. However, they are limited by design considerations and high-cost manufacturing operations. This article presents a way forward to utilize Fused Deposition Modelling – a 3D printing technique – to manufacture continuous carbon fibre-reinforced thermoplastics. Several parameters including number of reinforced layers, material impact and interlayer gap have been investigated and optimized using response surface method. Successful incorporation of modified novel nozzle design in a dual nozzle setup resulted in the realization of controlled manufacturing of continuously reinforced composites leading to reinforced yet smooth surface finished samples. Several samples were made, and mechanical testing, parameter optimization, strength calculations and fracture analysis were carried out. For polylactic acid (PLA), tensile strength of 112 MPa and flexural strength of 164 MPA were achieved – an almost 3 ti...
Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications
This study investigates ballistic response of a developed perforated armour plate against 12.7 mm... more This study investigates ballistic response of a developed perforated armour plate against 12.7 mm armour piercing tracer projectile. Experimental as well as numerical studies were carried out and the penetration of the projectile through a base aluminium plate was determined with and without the perforated armour plate. The armour piercing projectiles were able to penetrate the base armour plate in successive impacts. However, the combination of the perforated and base armour plates was able to stop the penetration of the armour piercing projectile. A finite element method-based numerical model was developed to investigate the defeating phenomenon of perforated and base armour plate combination. It was observed that the asymmetric impact of the projectile core did not produce large enough bending to fracture the core. However, the high hardness of the developed perforated plate was able to shatter the projectile core in multiple fragments which were then unable to penetrate the base...
Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications
Shaped charges are used in many civilian and military applications. This study focuses on the eff... more Shaped charges are used in many civilian and military applications. This study focuses on the effects of liner material and the type of explosive on the development of shaped charge jet. This was carried out by experimentation and numerical finite element-based modelling. Shaped charges were tested on a steel plate during the experimentation and the experimental data were used to validate the developed numerical model of the shaped charge. A hydrocode-based finite element model was able to predict the perforation and jet formation for the shaped charge, as well as the characteristics of the holes formed in the target plate. Several variations of the numerical model with the change of liner material and the filled explosive showed that the higher explosive resulted in higher velocity jet. The jet formation and velocity of jet were compared to determine the better performing combination of the material and explosive for the given shaped charge geometry. The underlying mechanisms were ...
In recent years, cohesive elements based on the cohesive zone model (CZM) have been increasingly ... more In recent years, cohesive elements based on the cohesive zone model (CZM) have been increasingly used within finite element analyses of adhesively bonded joints to predict failure. The cohesive element approach has advantages over fracture mechanics methods in that an initial crack does not have to be incorporated within the model. It is also capable of modelling crack propagation and representing material damage in a process zone ahead of the crack tip. However, the cohesive element approach requires the placement of special elements along the crack path and is, hence, less suited to situations where the exact crack path is not known a priori. The extended finite element method (XFEM) can be used to represent cracking within a finite element and hence removes the requirement to define crack paths or have an initial crack in the structure. In this article, a hybrid XFEM-cohesive element approach is used to model cracking in the fillet area using XFEM where the crack path is not known and then using cohesive elements to model crack and damage progression along the interface. The approach is applied to the case of an aluminium–epoxy single lap joint and is shown to be highly effective.
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