Applications of High-speed motion analysis system on Solid Rocket Motor (SRM)

Solid rocket motors typically include an outer case or shell that houses solid propellant grains. Internal insulation in a solid rocket motor is a layer of heat-barrier material placed between the internal surface of the case and the propellant which. The aim of the present study is to develop and characterize an asbestos-free rubber for use as rocket motor insulator which needs to be taken into account for protecting in the planning of space missions, in their design, and in their operation. Such insulation is based on aramid fiber in the pulp form, alumina and/or silica aerosol as reinforcement for Ethylene Propylene Diene Monomer (EPDM). Different formulations based on these fillers were prepared. The fillers dispersed in the EPDM polymeric matrix to obtain a homogenous master batch for curing. The physical, mechanical (density, hardness, tensile strength and elongation) and thermal properties (effective thermal conductivity) of different compositions were obtained. The ablation resistance of samples with different compositions was measured. Thermo-gravimetric analyses versus reinforcement content were obtained. The effect of changing aramid fiber in the pulp form, alumina and/or silica aerosol volume fractions was studied. For application for solid rocket motor insulation, Reinforcement of EPDM with KP improves the performance of the material with respect to mechanical properties and thermal properties (thermal conductivity) while not improving well the performance with respect to ablation resistance. Using hybrid reinforcement content (KP + Al + Si) inside EPDM improves the performance of EPDM with respect to mechanical properties, thermal properties, ablation resistance and decomposition resistance. The best volume fraction which gives the best performance of the insulation material is 10 Phr KP + 5 Phr Al + 5 Phr Si. A new type of insulation material using the hybrid reinforcements was developed for the first time.

Summary form only given. Polymer Optical Fibers embedded in the propellant of Solid Rocket Motors are demonstrated for monitoring strains higher than 10%. A new architecture incorporating a closed-loop fiber is proposed and its theoretical behaviour is experimentally verified. The propulsion system of Solid Rocket Motors (SRM) is considered as the most critical system in a guided missile as it powers the missile with predetermined characteristics. A key issue for the safety and reliability of those SRM missiles and consequently for the effective and economic management of missiles' inventory is the efficient Structural Health Monitoring of the energetic propellant grain. This work proposes the use of photonic sensors [1,2] for SRMs' continuous SHM as the preferable solution in such environments, due to their electromagnetic interference immunity and inherent electrical and explosion safe characteristics. Polymer Optical Fibers embedded with excellent bonding characteristics to the propellant material of SRM are demonstrated as an efficient sensing platform. The use of POFs for SHM applications is considered as more robust in terms of installation and operational reliability compared to silica fibers where their fragility leads to a high rejection ratio (around 60%) of unsuccessful installations due to fiber breakage during handling and this ratio is prohibitive when installing fibers in highly expensive units such as SRMs. PMMA POFs used both as jacketed cables or unjacketed bare fibers, were successfully embedded into solid propellant materials and afterwards mechanically loaded in special tensile tests equipment. The experiments were realised with a simple optical setup of a high power LED of 1 mW at 650nm and a photodetector operating at linear regime. By using special primers an excellent bonding between fibers and propellant was achieved allowing thus efficient strain transfer from the energetic material and avoiding relative slipping [3]. Two different configurations were employed, one of axial longitudinal incorporation of the POF along the specimen and the other by incorporation of a fiber loop segment in the longitudinally embedded fiber. The applied strain in the specimen is transferred partially axially to the straight fiber sections while it also allows the geometrical deformation of the embedded loop from the circular to elliptical shape. This deformation results in change of local bend radii along the looped fiber inducing thus additional bend losses. The intrinsic elasticity of the POFs and also the macro-bend originated losses under strain provide monitoring capability for strain and stress much higher than 10%. Additionally resulted plastic deformation of POFs in excessively high strains, is proposed to serve as a data/event logger important for recording materials' stress history.

Polymeric composites are widely used in aerospace. One such important use of polymeric composites is the filament-wound composite case for the Solid Rocket Motor (SRM). Environmental conditions expected during flight and other phases of the SRM’s life cycle affect its performance. The performance of SRM, in turn, depends primarily on the composite case and propellant grain. In this study, the performance evaluation of SRM with the composite case is carried out for different environmental conditions. These cases are designed to sustain very high pressure and temperature environments generated due to the combustion of propellant grains and are intended to perform adequately at any time during their service life. The performance evaluation test matrix is formulated considering various expected dynamic and thermal conditions. The small SRM with a composite case is subjected to planned tests as per the matrix, followed by static tests. The pressure versus time data is plotted for all test conditions. The ballistic parameters result of the virgin (without subjecting it to any test) small SRM is considered as a reference for comparative studies with the rest of all other test conditions results. All the ballistic performance test results are also analysed with respect to the pressure-time curve for mission bounds. The analysis of experimental test results reveals that various environmental dynamic conditions like random vibration, acceleration and shock, do not affect the composite case and the ballistic performance of a small SRM. The effect of grain temperature on ballistic performance is also found as expected.

Taylor-Culick flow is of importance on the interior ballistics of solid rocket motor (SRM). The combustion of solid fuel results in the motion of the wall boundary of the flow. Therefore, the understanding of Culick-like flow with a regressing wall plays a significant role in the study of SRM. However, the complex geometry of real fuel surface of SRM leads to considerable difficulty on the analysis and numerical simulation. In this paper, Navier Stokes equations coupled with Level-set equation are resolved to mimic the flows inside the combustion chamber with grain regression of the propellant. The four typical geometrical structure which corresponds to classical propellant grain shapes are simulated. The results demonstrate that the different geometrical structure in associate with flow direction could significantly affect the flow inside the combustion chamber. Besides flow turning could be substantially changed based on different geometrical configuration, isolated vortex could also be introduced under the influence of different injection schemes. Considering both flow turning and vortex play an important role in the combustion instability of the SRM, the geometrical design of grain should be taken additional care except for the traditional requirement of thrust.

Chain-flail delimbing-debarking technology is suitable for multi-tree processing of small-diameter trees. In the chain-flail debarking process, the rotation speed of the chain drum ranges 300-500 rpm. Therefore, a high-speed motion analysis is the only method to show what really happens in the debarking process. In this study, it was noticed that debarking occurs in a very short time (about 0.5 ms) when the chain hits the timber. If the chain hits the side of the tree, the chain just slides on the surface of the tree and is not able to debark the tree efficiently. In the determination of the impact force there is a clear correlation between the results obtained by a load cell mounted at the hitting point of the chain and those calculated using the impact time determined with a high-speed motion analysis system. This information makes it possible to determine the maximum impact force of the chain without measuring it.

During the ignition process of a solid rocket motor, the pressure changes dramatically and the ignition process is very complex as it includes multiple reactions. Successful completion of the ignition process is essential for the proper operation of solid rocket motors. However, the measurement of pressure becomes extremely challenging due to several issues such as the enormity and high cost of conducting tests on solid rocket motors. Therefore, it needs to be investigated using numerical calculations and other methods. Currently, the fundamental theories concerning the ignition process have not been fully developed. In addition, numerical simulations require significant simplifications. To address these issues, this study proposes a solid rocket motor pressure prediction method based on bidirectional long short-term memory (CBiLSTM) combined with adaptive Gaussian noise (AGN). The method utilizes experimental pressure data and simulated pressure data as inputs for co-training to predict pressure data under new operating conditions. By comparison, the AGN-CBiLSTM method has a higher prediction accuracy with a percentage error of 3.27% between the predicted and actual data. This method provides an effective way to evaluate the performance of solid rocket motors and has a wide range of applications in the aerospace field.

The medical far infrared (FIR) imaging system has recently been modified to be more sensitive, rapid and cheap. Also, the image format for processing on a personal computer and output format from integrated circuit of a FIR sensor have gradually been standardized. The objective of the report is to develop an application software to analyze clinical FIR images. We developed new programs which are written as macro programs on commercially available image processing software and by which any digital image data with known data format becomes applicable to the standard FIR image analysis system. NIH Image was introduced as the image processing software. Sequences of calls or routines for medical oriented image processing were written with macro codes in Macintosh computers. We aimed to obtain the same image processing functions which had been developed for medical computer thermography systems. Every source FIR image was converted into temperature images (thermograms). Marking on the same temperature region (isotherm), making temperature profiles (line scan) and temperature histograms of region of interest (ROI), drawing temporal temperature difference images (dT thermogram), comparing the temperature difference of two ROI (asymmetry detection thermogram), and displaying thermography index thermogram (TI thermogram) have been developed.

Technique to Assess Aging of Propellant Grain

Currently, the fast evolution of cameras in recent years has made them promising tools for diagnostics of Tokamak. The solution presented in this paper consists of a prototype of high-speed visible image acquisition and processing system (HVIAPs) dedicated for experimental advanced superconducting tokamak shape and position control. Graphics processing unit (GPU) and field-programmable gate array (FPGA) are typically used as accelerators or co-processors in addition to a CPU. Such a heterogeneous computing system can combine the advantages of its individual components. The main imaging equipment components used for this system are four high-resolution fast cameras equipped with fiber interface. Image data from the cameras are received by the frame grabber card based on the FPGA and transmitted to the GPU via the peripheral component interconnect express interface. The software support for the system includes low-level drivers and application programming interface libraries for all components and the algorithm developed for image processing. The offline image process results are compared to equilibrium fitting code, which is a commonly used reconstruction method, with an average error of 1.5 cm. The total processing time for one frame is less than 0.3 ms.

Purpose The dicentric chromosome assay (DCA), recognized as the gold standard for biological dosimetry in emergency radiation exposure, involves multiple key steps. Among these, metaphase image selection remains ambiguous and particularly challenging for beginners. This study evaluates the impact of metaphase image selection on dicentric (Dic) frequency during initial training. Materials and methods Peripheral blood (PB) from three healthy donors was irradiated with 2 Gy X-rays and incubated at 37 °C for 2 h for DNA repair. PB samples were then cultured for 48 h with phytohemagglutinin and colcemid. After fixation, metaphase spreads were prepared, Giemsa-stained, and images were captured by specific microscope imaging and image processing software. Three beginners independently selected and analyzed 50 metaphase images each. A trainer with experience in performing radiation emergency related DCA then reviewed and removed unsuitable images. The beginners reanalyzed Dic frequencies, supplementing with additional images as needed to reach 50 metaphases. Dic frequencies were compared before and after image refinement. Results Dic frequencies were lower in metaphase image pools selected by beginners compared to those refined by the trainer. The novices’ selections included numerous over-condensed metaphases, making Dic detection difficult. Conclusion Blood culture for 48 h permanent colcemid treatment increases the occurrence of over-condensed chromosomes, affecting Dic scoring. This study highlights the importance of proper training in metaphase image selection and structured education on quality assessment, including the use of specific microscope imaging and image processing software to ensure accurate biological dosimetry.

Chromatic and achromatic (AC) assessments of camouflage textiles have been critical to the defense researchers for concealment, detection, recognition, and identification (CDRI) of target signature against multidimensional combat background (CB). AC assessment and camouflage measurement techniques are simulated and experimented for assessment of camouflage textiles against CB. This model has been demonstrated for color measurement spectrophotometer, scanning electron microscopy (SEM), digital imaging, hyperspectral imaging, and image processing software (ImageJ) for the advancement and establishment of AC camouflage textiles assessment. The chromatic variations of 48 artificial target objects (TOBs) have been synthesized by image processing; the technique can be implemented for defense CB-CDRI assessment. Microstructural variation versus optical signal of woodland, desertland and stoneland CB materials have been elucidated by SEM magnification. The achromatic variation of CB materials have been demonstrated for the replacement of optical signal against modern remote sensing device to the imaging sensor. Color difference (Δ E), microstructural variations, pixel variations to imaging signal and standard deviation of CB materials have been represented for remote sensing surveillance of defense applications against TOB-CB-CDRI. Technical simulation of color, texture, gloss, and pixel intensity has been derived for AC-CDRI assessment of camouflage textiles in TOBs-CB environment.

In order to obtain the analytical method to compute the circumferential strain on a soft pulse separation device (PSD), deformation processes of the middle section of the soft PSD, the medicine propellant grain and the case are simplified into a two-dimensional plane strain state. It is found that the main factors affecting the circumferential strain of the soft PSD are the circumferential strain of the inner surface of the propellant grain and the gap between the soft PSD and the propellant grain. In order to study the failure mechanism of the soft PSD in the double-pulse solid rocket motor (SRM), a two-dimensional axisymmetric finite element method (FEM) model of the stress process of the soft PSD is established. The variation of the strain of the soft PSD with the internal pressure load is obtained. It is found that the excessive circumferential strain is the main reason for the failure of the soft PSD. Comparing the analytical calculations with the FEM results, it can be found that the analytical method value is slightly higher than the FEM value, so the analytical method results can be used to initially estimate the circumferential strain of the soft PSD and then predict the rationality and feasibility of the design scheme. In order to further study the failure mechanism of the soft PSD, a micro-CT test of in situ stretching of the soft PSD material is carried out and the variation of porosity and elongation of the material is studied. The test results showed that when the material elongation is large, the microinterface debonding rapidly expands into a penetrating damage, and the PSD structure fails. The conclusions obtained in this paper can provide a useful reference for the design of double-pulse SRM.

A three-dimensional (3D) laser scanning system is the main part of reverse engineering. It is a comprehensive technological system, including numerical control (NC), a laser, computer-aided design/manufacturing (CAD/CAM), precision mechanisms, computing image sampling, and image processing. Generally, it consists of a motion control system, an image sampling system, and an image processing system, etc. This paper focuses on introducing control principles, hardware constitutions, and software algorithms of the servo motion system, and analyzes and presents the hardware constitutions, software algorithms, and experimental results of the image sampling and processing system in great detail. Finally, the authors come to the conclusion that the errors all occur within the range ±0.1 mm.

Numerical analysis of unsteady multiple jet plume interactions

A laboratory scale experimental setup has been developed to explore an alternative source of solid propellant. A combination of potassium nitrate and ferric oxide embedded in epoxy binder constitutes the ingredients of the propellant used. A scanning electron microscope and nondestructive test (X-ray radiography) were utilized to study the crack surface and internal structure of the cured propellants. The influence of the epoxy mixing ratio on the sample density has been studied. Two solid propellant grain configurations were utilized to study the performance characteristics in terms of the thrust generated. It was found that the manufacturer’s mixing ratio provided the optimum density results for the given set of configurations tested. The multiperforated grain configuration showed higher performance in terms of trust when compared with the single perforated grain configuration.