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This paper aims to investigate a novel impact time control guidance (ITCG) law based on the sliding mode control (SMC) for a nonmaneuvering target using the predicted interception point (PIP).

To intercept the target with the minimal miss distance and desired impact time, an estimation of time-to-go is introduced. This estimation results in a precise impact time for multimissiles salvo attack the target at the same time. Even for a large lead angle, the desired impact time is achieved by using the sliding mode and Lyapunov stability theory. The singularity issue of the proposed impact time guidance laws is also analyzed to achieve an arbitrary lead angle with the desired impact time.

Numerical scenarios with desired impact time are presented to illustrate the performance of the proposed ITCG law. Comparison with the state-of-art impact time guidance laws proves that the guidance law in this paper can enable the missile to intercept the target with minimal miss distance and final impact time error. This method enables multiple missiles to attack the target simultaneously with different distances and arbitrary lead angles.

An ITCG law based on sliding mode and Lyapunov stability theory is proposed, and the switching surface is designed based on a novel estimation time-to-go for the missile to intercept the target with minimal miss distance. To intercept the target with initial arbitrary lead angles and desired impact time, the authors analysis the singular issue in SMC to ensure that the missile can intercept the target with arbitrary lead angle. The proposed approach for a nonmaneuvering target using the PIP has simple forms, and therefore, they have the superiority of being implemented easily.

The purpose of this paper is to propose a new nonlinear guidance law to satisfy terminal impact-angle constraints against a stationary target in every possible planar surface-to-surface engagement scenario. The proposed guidance scheme is developed based on the geometry of a circular arc trajectory. The proposed guidance scheme is developed based on the geometry of circular arc trajectory. This trajectory is calculated based on the terminal impact angle and target range. The efficacy of the proposed guidance scheme is demonstrated through numerical simulations. The proposed scheme is compared with existing guidance schemes and relevant analysis is provided.

The paper develops a new nonlinear guidance law to satisfy terminal impact-angle constraints against a stationary target in every possible planar surface-to-surface engagement scenario. The proposed guidance scheme is developed based on the geometry of a circular arc trajectory. This guidance scheme is further extended to moving targets.

The proposed guidance intercepts a stationary target with a smooth lateral acceleration command, which is desirable for realistic implementation. The efficacy of the approach is demonstrated through numerical simulation. A comparative study with the existing algorithm is presented and it is shown that the proposed algorithm is better on many counts.

There are many approach exists in the literature for impact-angle guidance laws. The paper proposes a computationally efficient guidance law using geometric and kinematic properties. As the approach produces smooth command, it has a practical relevance. A comparative study shows superiority on some counts (miss distance, flight time, smoothness).

Ballistic missile-resistant impact panels have seen fair advancement over the years, especially in military applications. However, high cost, as well as a changing materials landscape, has impressed the need for a deeper understanding of impact mechanism as well as of new permutations in design strategy development. Parameters such as projectile impact angle, panel impact location as well as application of multilayer sandwich panels are not fully explored and characterised. In this work, finite element method simulation methodology is used on a 25 mm by 25 mm plate of 3.5 mm thickness to investigate the above-mentioned parameters and conditions. Solid elements using Johnson–Cook damage material models are developed. Two common impact angles of 90 and 45° at centre and plate-edge locations are investigated for single-layer titanium alloy and carbon steel panels. Subsequently, a bilayer panel comprising of titanium alloy at the impact layer with the same overall plate thickness is investigated for impact at five different impact speed (ranging from 100 ms^-1 to 500 ms^-1). The displacements and von Mises stresses are documented for all cases, and it is shown that angular impact angles bring about greater plastic deformations as well as higher fracture likelihood compared to normal angle impact. Findings also indicate that with an addition of 1 mm thick Ti-6Al-4V front bilayer, the impact resistance of the high carbon steel is significantly improved (up to twice the impact load), especially at higher impact velocities. The study documents the properties of titanium alloy–carbon steel bilayer armoured panel, which shows good promise for its implementation due to its superior performance and its cost-savings potential.

In this work, finite element method simulation methodology is used to investigate the above-mentioned parameters and conditions. Solid elements using Johnson–Cook damage material models are developed. Two common impact angles 90 and 45° at centre and plate-edge locations are investigated for single-layer titanium alloy and carbon steel panels, and, subsequently, a bilayer panel comprising of titanium alloy for the outer layer is investigated for the combination of the same aforementioned materials. Five different impact speed effects are studied.

The effects and trends of displacements and stresses are documented for all cases and shown to indicate angular impact angles bringing about greater plastic deformations as well as higher fracture likelihood compared to normal angle impact. Findings also show that with an addition of 1 mm thick Ti-6Al-4V front bilayer, the impact resistance of the high carbon steel is significantly improved, especially at higher impact velocities.

The study documents the properties of titanium alloy–carbon steel bilayer armoured panel, which shows good promise for its implementation due to its superior performance and its cost-savings potential.

This paper aims to clarify the relationship between the slurry erosion and one of the case hardening treatments, i.e. boronizing in this study, for AISI-5117 steel alloy. AISI-5117 steel alloy was used because of its variety applications in the field of submarine equipment. Most of the slurry erosion factors such as velocity, impact angle and mechanism of erosion were studied at different impact angles.

At first, the samples were prepared and subjected to the boronizing treatment in controlled atmosphere. By using a slurry erosion test-rig, all experiments for studying the slurry erosion factors were carried out. Moreover, the studied specimens were investigated via scanning electron microscope, optical microscope and X-ray diffraction to study the erosion mechanism in the different conditions.

It was expected that the boronization of the AISI-5117 steel would increase its slurry erosion resistance due to its positive impact on the surface hardness. However, the results observed show the opposite, where the boronization of AISI-5117 steel decreased its slurry erosion resistance as implied by the increase of the mass loss percentage at all impact angles.

This research, for the first time, exhibits the effect of boronizing treatment on the slurry erosion in different impact factors accompanied by the erosion mechanism at each impact angle.

The fiber reinforced polymer composites are becoming more critical because of their exceptional mechanical properties and lightweight structures. Fused filament fabrication (FFF) is a three-dimensional (3D) printing technique that can manufacture composite structures. However, the effect of impact performance on the structural integrity of FFF made composites compared to the pre-preg composites is a primary concern for the practical usage of 3D printed parts. Therefore, this paper aims to investigate the effect of different processing parameters on the impact performance of 3D printed composites.

This paper investigates the impact of build orientation, fiber stacking sequence and fiber angle on the impact properties. Two build orientations, three fiber stacking sequences and two different fiber angles have been selected for this study. Charpy impact testing is carried out to investigate the impact energy absorption of the parts. Onyx as a matrix material and two different types of fibers, that is, fiberglass and high strength high temperature (HSHT) fiberglass as reinforcements, are used for the fabrication.

Results indicate that build orientation and fiber angle largely affect the impact performance of composite parts. The composite part built with XYZ orientation, 0º/90º fiber angle and B type fiber stacking sequence resulted into maximum impact energy. However, comparing both types of fiber reinforcement, HSHT fiberglass resulted in higher impact energy than regular fiberglass.

This study evaluates the damage modes during the impact testing of the 3D printed composite parts. The impact energy absorbed by the composite samples during the impact testing is measured to compare the effect of different processing conditions. The investigation of different types of fiberglass reinforced with Onyx material is very limited for the FFF-based process. The results also provide a database to select the different parameters to obtain the required impact properties.

This paper aims to present the results of aerodynamic calculation of impact the main rotor on the fuselage and the tail of a light gyroplane. This kind of vehicle is a type of rotorcraft which uses a non-powered rotor in autorotation to develop lift and engine-powered propeller to provide the thrust. Both of them disturb the flow around the gyroplane body (gyroplane fuselage and tail) and influence on its static stability. The main goal of the presented research was to find the magnitude of this influence. To measure this effect, the main stability derivatives changes of gyroplane body were investigated.

The CFD analysis of the complete gyroplane was made. Computation was performed for the model of gyroplane which was equipped with the two sub-models of the main rotor and the engine-powered propeller. Both of them were modelled as the actuator discs. This method allows to compute the aerodynamic impact of rotating components on the gyroplane body. All aerodynamic analysis was made by the MGAERO software. The numerical code of the software bases on the Euler flow model. Next, the resulting aerodynamic coefficients were used to calculate the most important stability derivatives of the gyroplane body.

The result obtained by computation presents the change in the most important aerodynamic coefficients and stability derivatives of the gyroplane body caused by the impact of its main rotor. Moreover, the result includes the change of the aerodynamic coefficients and stability derivatives caused by change of the main rotor configuration (change of rotation rate and angle of incidence) and change of the flight condition (gyroplane angle of attack sideslip angle and flight speed).

Analysis of the main rotor impact will be very useful for evaluation of dynamic stability of the light gyroplane. Moreover, the results will be helpful to design the horizontal and vertical tail for the light gyroplane.

This paper presents the method of the numerical analysis of the static stability of the light gyroplane’s body. The results of analysis present the impact of disturbance generated by the rotating main rotor on the static stability of the gyroplane body. Moreover, the impact of the main rotor configuration change and the flight condition change on the static stability were investigated too. The evaluation of the gyroplane’s body static stability was made by the stability derivatives. The methodology and obtained result will be very useful for analysis of the dynamic stability of the light gyroplanes. Moreover, the results will be helpful during design the main components of the gyroplane like vertical and horizontal tail.

The purpose of this paper is to present a novel guidance law that is able to control the impact time while the seeker’s field of view (FOV) is constrained.

The new guidance law is derived from the framework of Lyapunov stability theory to ensure interception at the desired impact time. A time-varying guidance gain scheme is proposed based on the analysis of the convergence time of impact time error, where finite-time stability theory is used. The circular trajectory assumption is adopted for the derivation of accurate analytical estimation of time-to-go. The seeker’s FOV constraint, along with missile acceleration constraint, is considered during guidance law design, and a switching strategy to satisfy it is designed.

The proposed guidance law can drive missile to intercept stationary target at the desired impact time, as well as satisfies seeker’s FOV and missile acceleration constraints during engagement. Simulation results show that the proposed guidance law could provide robustness against different engagement scenarios and autopilot lag.

The presented guidance law lays a foundation for using cooperative strategies, such as simultaneous attack.

This paper presents further study on the impact time control problem considering the seeker’s FOV constraint, which conforms better to reality.

The purpose of this paper is to present a novel guidance law for hypervelocity descent to a stationary target such that the impact angle and impact velocity can be constrained.

The proposed method is based on inverse dynamics and is designed using a third-order Bézier curve approximation to the reference trajectory.

Simulations indicate that the proposed law is able to satisfy impact angle and impact velocity constraints as well as follow control and path limitations in the case of guidance under perturbations. Comparisons with other methods also indicate better performance.

The onboard implementation requires an offline selection of Bézier parameters.

The presented scheme could be extremely important for further research on automated onboard control of impact angle and velocity for both re-entry and terminal guidance laws.

This paper presents an innovative method for the solution of an inverse dynamics-based guidance law using Bézier curve approximation.

The purpose of this study is to design and develop new spiral head projectiles undergoing ballistics impact.

The introduction of the rifled barrel in firearms made projectile spin during its flight path. The central translational velocity (impact velocity) is one parameter to defeat/penetrate the target in the penetration process. Another important parameter considered to be the shape of the projectile. Many types of projectile shapes have been designed to defeat the target. In the recent years, ogival nose shape is one of the well-known projectile shapes in use abundantly. The present research is made to design the nose shape so as to use the spin during the penetration of target effectively. In this study, a new spiral head projectile shape is proposed and designed, which uses the rotation of projectile (spin) for penetrating the Al7075-T6 target. When the ogive and new spiral head projectile is impacted on Al 7075-T6 target of 12.5 mm, 18 mm thicknesses at ordnance velocities, the residual velocity is evaluated numerically using ANSYS/Explicit Dynamics at normal impact condition. Two projectile materials, steel 4340 and tungsten alloy, are used as projectile materials. Along with the translational velocity, rotation velocities (spin rate) 13,000, 26,000 and 52,000 rad/s also provided to projectile. The residual velocities verses spin rate are plotted for different spiral angle projectiles for impact velocities 1,000–1,500 m/s, at normal impact conditions on the Al 7075-T6 target. Compared with the ogive nose projectile, the proposed new spiral head projectile made of tungsten alloy is significantly effective.

Spiral head projectile having tungsten alloy material gives encouraging results at 12.5 mm target thickness. The new spiral head projectile is damaged partially. At 18 mm target thickness impact conditions, it is observed that the projectile head is completely damaged. The effectiveness of spiral head projectile on a target plate thickness of 18 mm is considered to study the impact condition.

All the above results need to be experimentally verified. However, the basic numerical model used in the present study, i.e. the basic ogive nose numerical model with only translational energy, is well validated with penetration theory available in literatures.

The designed new spiral head projectile is only effective with tungsten alloy material within considered design parameters. For steel 4340 material, the spiral head projectile is less effective than the ogive nose projectile. In tungsten alloy projectiles, by observing all considered spiral angles, 30-degree spiral angle projectile gives the best performance at most of the considered impact velocity conditions.

The proposed research outputs are original, innovative and, have lot of importance in defence applications particularly in arms and ammunitions.

The main purpose of this work is to explore the erosion wear characteristics of additively manufactured aluminium alloy. Additive manufacturing (AM), also known as three-dimensional (3D) manufacturing, is the process of manufacturing a part designed in a computer environment using different types of materials such as plastic, ceramic, metal or composite. Similar to other materials, aluminum alloys are also exposed to various wear types during operation. Production efficiency needs to be aware of its reactions to wearing mechanisms.

In this study, quartz sands (SiO₂) assisted with oxide ceramics were used in the slurry erosion test setup and its abrasiveness on the AlSi10Mg aluminum alloy material produced by the 3D printer as selective laser melting (SLM) technology was investigated. Quartz was sieved with an average particle size of 302.5 µm, and a slurry environment containing 5, 10 and 15% quartz by weight was prepared. The experiments were carried out at the velocity of 1.88 (250 rpm), 3.76 (500 rpm) and 5.64 m/s (750 rpm) and the impact angles 15, 45 and 75°.

With these experimental studies, it has been determined that the abrasiveness of quartz sand prepared in certain particle sizes is directly related to the particle concentration and particle speed, and that the wear increases with the increase of the concentration and rotational speed. Also, the variation of weight loss and surface roughness of the alloy was investigated after different wear conditions. Surface roughness values at 750 rpm speed, 10% concentration and 75° impingement angle are 0.32 and 0.38 µm for 0 and 90° samples, respectively, with a difference of approximately 18%. Moreover, concerning a sample produced at 0°, the weight loss at 250 rpm at 10% concentration and 45° particle impact angle is 32.8 mg, while the weight loss at 500 rpm 44.4 mg, and weight loss at 750 rpm is 104 mg. Besides, the morphological structures of eroded surfaces were examined using the scanning electron microscope to understand the wear mechanisms.

The researchers verified that this specific coating condition increases the slurry wear resistance of the mentioned steel. There are many studies about slurry wear tests; however, there is no study in the literature about the quartz sand (SiO₂) assisted slurry-erosive wear of AlSi10Mg alloy produced with AM by using SLM technology. This study is needed to fill this gap in the literature and to examine the erosive wear capability of this current material in different environments. The novelty of the study is the use of SiO₂ quartz sands assisted by oxide ceramics in different concentrations for the slurry erosion test setup and the investigations on erosive wear resistance of AlSi10Mg alloy manufactured by AM.