ahmad serjouei - Academia.edu (original) (raw)

Papers by ahmad serjouei

Research paper thumbnail of Influence of Geometry and Hardness of the Backing Plate on Ballistic Performance of Bi-Layer Ceramic Armor

Procedia Engineering, 2017

Research paper thumbnail of Thermomechanics of printed anisotropic shape memory elastomeric composites

International Journal of Solids and Structures, 2016

Research paper thumbnail of Empirical Ballistic Limit Velocity Model for Bi-layer Ceramic–Metal Armor

International Journal of Protective Structures, 2015

Research paper thumbnail of Modelling and Analysis of Bi-layer Ceramic-Metal Protective Structures

Technical ceramics due to their high specific hardness and compressive strength under pressure lo... more Technical ceramics due to their high specific hardness and compressive strength under pressure loading are attractive materials for armor structures. However, the low toughness of the ceramics is limiting their usage in practical designs. Adding a strong and tough plate at the back of the ceramic plate such as metal or polymer composite laminate, is one of the states of the art armor design that is extensively studied by researchers. Due to the cost of field experiments in defense industry, development of analytical, numerical/empirical models to estimate the ballistic velocity of armor systems by considering geometry of the projectile and target structure is gaining importance. Optimization of the armor design for either weight or thickness is also an important criterion. Furthermore, improving the toughness of the ceramic employing different means like adding metallic phases or pre-stressing them is of considerable interest. In the present thesis, a semi-analytical model is presen...

Research paper thumbnail of Pre-stress effect on confined ceramic armor ballistic performance

International Journal of Impact Engineering, 2015

ABSTRACT A numerical technique for the simulation of pre-stressed confined ceramic targets under ... more ABSTRACT A numerical technique for the simulation of pre-stressed confined ceramic targets under long rod projectile (LRP) impact, using explicit software, AUTODYN®, is proposed. The proposed model is validated by comparing the ballistic performance results with the available experimental data in the literature. Impact simulations of the confined ceramic targets with different pre-stress conditions, namely radial, axial and hydrostatic, as well as without pre-stress for benchmarking are reported. The effects of these different pre-stress conditions on the ballistic performance of the ceramic target are explored. The upper limits of transition velocity for the targets of different pre-stress conditions are obtained. It is shown that dwell of the LRP on the ceramic interface is influenced by the pressure, obtained from pre-stressing, at the initial failure position in SiC target. It is shown that pressure at the initial failure position increases linearly with the upper limit of transition velocity.

Research paper thumbnail of Experimental validation of BLV model on bi-layer ceramic-metal armor

International Journal of Impact Engineering, 2015

A semi-analytical method to estimate the ballistic limit velocity (BLV) of bi-layer ceramic-metal... more A semi-analytical method to estimate the ballistic limit velocity (BLV) of bi-layer ceramic-metal armor under normal impact proposed in the International Journal of Impact Engineering, Vol 52 (2013) 37-46 is verified through gas gun experiments on alumina-aluminium armor system and simulations. The laboratory experiments mostly contained an inherent yaw. Initially, AUTODYN ® hydrocode based numerical model, in which literature material model parameters are used, is proposed and the experimental measurements are compared with numerical simulation data. It is then shown that the semi-analytical BLV model results matches fairly well with normal impact simulation results and also limited literature experimental data. The significance of the validated semi-analytical model in estimation of BLV of the bilayer ceramicemetal armor systems is described. Finally, optimal thickness and mass of the armor design for given total thickness and areal density are obtained.

Research paper thumbnail of An Empirical Model for the Ballistic Limit of Bi-layer Ceramic/metal Armour

Procedia Engineering, 2014

Research paper thumbnail of On the Design of Bi-Layer Armor Materials

Solid State Phenomena, 2012

ABSTRACT

Research paper thumbnail of Ballistic impact on bi-layer alumina/aluminium armor: A semi-analytical approach

International Journal of Impact Engineering, 2013

This paper presents a semi-analytical approach on the performance of ceramic/metal armor under ba... more This paper presents a semi-analytical approach on the performance of ceramic/metal armor under ballistic impact. Numerical simulations for alumina/aluminum armor impacted by 20 mm APDS in AUTODYN were carried out and verified against the experimental data. Comprehensive numerical simulations were performed using the verified numerical model material parameters providing corroborative data for ensuing discussions. A semi-analytical model relating projectile residual velocity, impact velocity and armor ballistic limit velocity (BLV) is presented for impact of hard projectile against ceramic/metal armor. It is shown that the projectile residual velocity and BLV satisfy the replica scaling laws. Based on the replica scaling laws of projectile residual velocity and BLV, an empirical equation for BLV is obtained and used for armor optimization applications giving reasonable results similar to experiments available in the literature.

Research paper thumbnail of Influence of Geometry and Hardness of the Backing Plate on Ballistic Performance of Bi-Layer Ceramic Armor

Procedia Engineering, 2017

Research paper thumbnail of Thermomechanics of printed anisotropic shape memory elastomeric composites

International Journal of Solids and Structures, 2016

Research paper thumbnail of Empirical Ballistic Limit Velocity Model for Bi-layer Ceramic–Metal Armor

International Journal of Protective Structures, 2015

Research paper thumbnail of Modelling and Analysis of Bi-layer Ceramic-Metal Protective Structures

Technical ceramics due to their high specific hardness and compressive strength under pressure lo... more Technical ceramics due to their high specific hardness and compressive strength under pressure loading are attractive materials for armor structures. However, the low toughness of the ceramics is limiting their usage in practical designs. Adding a strong and tough plate at the back of the ceramic plate such as metal or polymer composite laminate, is one of the states of the art armor design that is extensively studied by researchers. Due to the cost of field experiments in defense industry, development of analytical, numerical/empirical models to estimate the ballistic velocity of armor systems by considering geometry of the projectile and target structure is gaining importance. Optimization of the armor design for either weight or thickness is also an important criterion. Furthermore, improving the toughness of the ceramic employing different means like adding metallic phases or pre-stressing them is of considerable interest. In the present thesis, a semi-analytical model is presen...

Research paper thumbnail of Pre-stress effect on confined ceramic armor ballistic performance

International Journal of Impact Engineering, 2015

ABSTRACT A numerical technique for the simulation of pre-stressed confined ceramic targets under ... more ABSTRACT A numerical technique for the simulation of pre-stressed confined ceramic targets under long rod projectile (LRP) impact, using explicit software, AUTODYN®, is proposed. The proposed model is validated by comparing the ballistic performance results with the available experimental data in the literature. Impact simulations of the confined ceramic targets with different pre-stress conditions, namely radial, axial and hydrostatic, as well as without pre-stress for benchmarking are reported. The effects of these different pre-stress conditions on the ballistic performance of the ceramic target are explored. The upper limits of transition velocity for the targets of different pre-stress conditions are obtained. It is shown that dwell of the LRP on the ceramic interface is influenced by the pressure, obtained from pre-stressing, at the initial failure position in SiC target. It is shown that pressure at the initial failure position increases linearly with the upper limit of transition velocity.

Research paper thumbnail of Experimental validation of BLV model on bi-layer ceramic-metal armor

International Journal of Impact Engineering, 2015

A semi-analytical method to estimate the ballistic limit velocity (BLV) of bi-layer ceramic-metal... more A semi-analytical method to estimate the ballistic limit velocity (BLV) of bi-layer ceramic-metal armor under normal impact proposed in the International Journal of Impact Engineering, Vol 52 (2013) 37-46 is verified through gas gun experiments on alumina-aluminium armor system and simulations. The laboratory experiments mostly contained an inherent yaw. Initially, AUTODYN ® hydrocode based numerical model, in which literature material model parameters are used, is proposed and the experimental measurements are compared with numerical simulation data. It is then shown that the semi-analytical BLV model results matches fairly well with normal impact simulation results and also limited literature experimental data. The significance of the validated semi-analytical model in estimation of BLV of the bilayer ceramicemetal armor systems is described. Finally, optimal thickness and mass of the armor design for given total thickness and areal density are obtained.

Research paper thumbnail of An Empirical Model for the Ballistic Limit of Bi-layer Ceramic/metal Armour

Procedia Engineering, 2014

Research paper thumbnail of On the Design of Bi-Layer Armor Materials

Solid State Phenomena, 2012

ABSTRACT

Research paper thumbnail of Ballistic impact on bi-layer alumina/aluminium armor: A semi-analytical approach

International Journal of Impact Engineering, 2013

This paper presents a semi-analytical approach on the performance of ceramic/metal armor under ba... more This paper presents a semi-analytical approach on the performance of ceramic/metal armor under ballistic impact. Numerical simulations for alumina/aluminum armor impacted by 20 mm APDS in AUTODYN were carried out and verified against the experimental data. Comprehensive numerical simulations were performed using the verified numerical model material parameters providing corroborative data for ensuing discussions. A semi-analytical model relating projectile residual velocity, impact velocity and armor ballistic limit velocity (BLV) is presented for impact of hard projectile against ceramic/metal armor. It is shown that the projectile residual velocity and BLV satisfy the replica scaling laws. Based on the replica scaling laws of projectile residual velocity and BLV, an empirical equation for BLV is obtained and used for armor optimization applications giving reasonable results similar to experiments available in the literature.