Subsea separation is an attractive and economic solution to develop deep offshore oil and gas fields producing fluid without hydrate or wax. The subsea separation system should be reliable to ensure successful operation in a wide range of multiphase flow regime. A subsea separator can avoid or simplifying costly surface platforms of floating vessels, as well as being an efficient tool to enhance hydrocarbon production. One solution of interest is the separation and re-injection of water at the seabed to avoid bringing the water up to the surface facility. In this study, liquid-liquid flow characteristics inside in-line type subsea separation system are investigated for the design of subsea separation system. The separation efficiency of the subsea separator is determined through experiments that are the liquid-liquid phased separation. Also internal swirl element (ISE) modeling of the separator was optimized. The analysis results were utilized to improve the reliability and efficiency of the subsea separation system.

Over the past 2 decades, GLCC © compact separators have been replacing the conventional vessel type separators in the Oil & Gas Industry, because of its numerous advantages. Despite these advantages, GLCC separators face two critical problems affecting the performance under extreme operating conditions, namely, Liquid Carry Over (LCO) into the gas leg and Gas Carry Under (GCU) into the liquid leg. This study focuses on the LCO phenomenon. Having a deeper insight into the LCO flow phenomenon helps us to enhance the technical performance of GLCC at these extreme conditions. Several studies were presented in the past on experimental investigations and mechanistic modeling of LCO. In the above cases, mechanistic modeling of LCO was based on Zero Net liquid Holdup (ZNLH) parameter. The liquid holdup in the upper part of the GLCC before it is blown out by gas flow is referred to as ZNLH. ZNLH is an important phenomenon affecting the GLCC pressure behavior and performance characteristics. Above mentioned experimental investigations performed to calculate ZNLH were carried out under static conditions where the effects of superficial liquid velocities were neglected. Investigations have been carried out in this study under dynamic conditions to evaluate the effect of superficial liquid velocities on ZNLH. We found that Dynamic ZNLH results are different from static ZNLH data as they show lower liquid holdup for the same gas velocities. A mechanistic model is proposed in this study to predict dynamic ZNLH and this model is validated against the dynamic ZNLH experimental data. It may be noted that a suitable ZNLH model will help in improving the predictions of the LCO mechanistic model considerably.

A standard high-solids vessel (SHSV) concept design approach using pulse jet mixers (PJM) has been proposed by the US Department of Energy (DOE) for the Hanford Tank Waste Treatment and Immobilization Plant (WTP) as a potential replacement for several vessels that will be used to process highly radioactive waste. To assist with the evaluation of the SHSV concept, at DOE’s direction, the WTP Project recently completed qualification testing of the SHSV PJM mixing system to verify the design. Testing of the SHSV design, conducted at full scale, was split into two phases. The first phase of testing developed PJM controls that supported all operational modes under a set of most adverse fluid conditions. The second phase of testing used the PJM operating strategy, established during the first phase, to perform qualification testing to verify that the mixing system design supports the transfer, de-inventory, throughput, and sampling functional requirements of the SHSV. The different control methods that were used to operate PJMs in simulants exhibiting Newtonian and non-Newtonian rheological properties with high solids loading are presented. The PJM system of the SHSV uses six pulse tubes distributed in a circular array. Each pulse tube (3000 liters nominal volume) is connected to a jet pump pair (JPP) by means of an air link line. The JPP powers the PJM operation by applying a vacuum to refill the PJM (suction phase), pressurizing the PJM to discharge the pulse tube content at a target velocity (drive phase), and releasing the compressed air to allow the PJM to depressurize into a ventilation system (vent phase) designed for contaminated air. A PJM control system was developed to maximize the PJM operation and minimize potential impact to the structural integrity of the vessel. The experimental results showed effective control of the system parameters. The system response demonstrated reliable control of the drive set pressure, the drive time, and synchronization. The PJM control system design also proved robust in mobilizing settled solids.

Polymethylmethacrylate (PMMA) has been widely utilized to manufacture the covers of aircraft cockpits, naval vessels, car windows and so on, due to their high transmittance, low density, easy processing formability, high corrosion resistance and excellent mechanical properties. Under special conditions such as ejection lifesaving, the PMMA plate needs to be split precisely by explosion cutting technology. Hence, an accurate numerical simulation of PMMA structures is significantly important in engineering application. This paper aims to study the cutting behavior of PMMA plate numerically and investigate the influencing factors on cutting performance of PMMA plates. First of all, the simulation of explosion cutting process of PMMA plate is carried out by a non-linear explicit solver in LS-DYNA software using the fluid-solid coupling method. Jones-Wilkins-Lee (JWL) equation of state is used to simulate the relationship between the transient pressure and specific volume of explosives during explosion. The material model considering failure behaviors is used in the simulation. Additionally, the influence of explosive dosage as well as explosive type on the cutting performance of PMMA plate is investigated. Furthermore, the effect of PMMA geometry size on cutting performance is discussed. This study contributes to the knowledge for the design of PMMA structures which needs explosion cutting and the selection of explosive dosage and explosive type.

This paper presents a successful functional design for a Robust Dynamic Positioning System (RDPS) capstone project. This design is created by using block diagrams with the inputs and outputs for all levels in order to build and test a vessel platform. The design at level 0 is a Light Detection and Ranging (LIDAR) sensor to determine position of the vessel. Level 1 is the design of all hardware components. Level 2 shows the internal communications for each component. The results of building this platform with the real time test of the platform with the controllers is presented at level 3. An Adaptive and Segmented Proportional Integral Derivative (ASPID) controller has been designed to meet the design performances of this platform.

Endovascular treatment has become the standard for intracranial aneurysm management. In vitro systems including an artery model are required for devices evaluation and clinician training. Although silicone is usually use for such model, its compliance is known to be lower than blood vessels. The purpose of this study was to analyze the influence of model material compliance on flow properties. Silicone and 12 [wt%] poly (vinyl alcohol) hydrogel (PVA-H) were used to create two box-shaped models of significantly different compliance. The inner lumen geometry was a 4 [mm] diameter straight tube (parent vessel) and a 10 [mm] diameter sphere representing the aneurysm. A blood-mimicking fluid made of a mixture of glycerin, water and sodium iodide was used to reproduce the viscosity and density of blood and fit models refractive index. The circulation system consisted of a pulsatile blood pump and resistance valve. A flow rate of 250±50 [ml/min] and pressure from 75 to 115 [mmHg] were set inside the model. Pressure and flow rate sensors were used to monitor flow conditions before and after the model. Particle image velocimetry (PIV) was performed to record the difference of flow patterns inside the aneurysm of both model using a Nd:YAG solid laser system and fluorescent particles. Results revealed a significant change of flow conditions due to model compliance. Attenuation of the flow rate pulse was recorded between the inlet and the outlet of the both model. This attenuation was 51% for PVA-H model. Moreover, a time lag between outlet pressure and outlet flow rate curves was recorded in both model. This time lag was longer with the PVA-H model, as this model exhibit a greater compliance. PIV experiments revealed significant changes of flow patterns and velocity inside the aneurysm. Because of its high compliance, PVA-H model walls moved under the pulsatile conditions. A change of flow direction and decrease of its velocity were observed near the proximal wall of the aneurysm, compared to the silicone model. Such differences might modify the stress on the wall of the aneurysm. To conclude, our experiments revealed that compliance has significant impacts on flow properties and should be taken into account for in vitro vascular model manufacturing.

Intravascular treatment is known as one of effective treatment methods for cerebral aneurysms. One problem of this therapy is that an intravascular treatment device unexpectedly moves and a tip of the device strongly contacts on a vessel wall. This unexpected movement of the device causes vascular injury. In actual treatment, 2D X-ray image is used. It is difficult for an operator to estimate 3D position of the device from the 2D X-ray image. In this study, we propose estimation methods for 3D position of devices using a X-ray image and a 3D blood vessel model. At the first step of estimation procedure, a 3D position of X-ray image, a 3D blood vessel model and X-ray source (Xs) are determined by 2D/3D registration method. The actual 3D position of the device tip (P) is placed on the straight line between Xs and P. Moreover, its position is limited within the 3D vessel model. From characteristics, the 3D position of the device tip is estimated. In this study, two methods to estimate the 3D position of the device are proposed. First: A closest point to the straight line from the center line of the blood vessel model is defined as the position in 3D space of the guidewire (one-point estimation method). Second: A mean value of points on the straight line inside the blood vessel model is defined as the position in 3D space of the guidewire (average estimation method). The accuracy of estimation methods depends on angle of X-ray irradiation. In this study, the relationship between the accuracy of estimation methods and the angle of X-ray irradiation. The estimation accuracy was investigated using numerical calculation. In the case of a simple blood vessel shape, the error of the estimation was proportional to the angular difference between an ideal and an actual. The errors of the estimated arc length parameter at the ideal angle of X-ray irradiation were 0.002 mm and 0.078 mm, respectively. This result shows that this method is effective for simple blood vessel shape. In future work, other factors to affect the accuracy are also investigated.

There is a need for better 3-D model representations of cerebrovasculature particularly on the order of arterioles. Such a model would have many applications and could be a useful tool for those conducting studies involving the brain and its function. The load bearing effects of the vasculature can be better studied with such a model, such as in the case of large strains. In addition, by having a continuous hollow structure, studies involving flow properties can be conducted at a whole scale rather than in a segmented view. Such studies are critical to the advancement of knowledge about the brain and its mechanics which can lead to advancements in preventative and curative care, as well as preventative safety measures. The model developed in this paper could serve as a tool in such studies. A fractal L-system is used to define the branching nature of the model. As such a growing tree structure is developed and characterized by its bifurcation at the end of a vessel segment. The index of bifurcation, α , is a parameter that controls the behavior of the two generated daughter vessels. The model presented here grows from a single parent branch into a bifurcation each of which then bifurcates as many times as specified. The length and diameter of the two daughter vessels will be a function of the respective parent’s length and diameter as well as a value α . The branching angle of the two daughter vessels will be entirely controlled by α. The hollow continuous nature of the model allows for it to be used as a representation of the arteriole structures in the brain. There is also use for such a model in other areas of the body, however, this study will focus on the representation of the cerebrovasculature. The end result is a branching tree model generated in Abaqus which is continuous, hollow and capable of extensive generation with uses in modeling complex cerebrovascular mechanics.

As it has been shown previously, the blood flow in the heart and the main vessels is a self-organizing tornado-like flow of a viscous fluid, exhaustively described by the particular solution of nonstationary hydrodynamic equations coined in 1986. This solution is implemented in a local dynamic cylindrical coordinate system, which origin moves with the flow. Streamlines of these flows are characterized with an axial symmetry and determine certain restrictions to the geometry of the flow channels. It has been proved, that the experimentally measured orientations of intraventricular trabeculae and dynamic geometric characteristics of the aortic flow channel during the cardiac cycle satisfy the conditions for the self-organization of tornado-like blood flow. This enables to obtain relative estimates of the flow parameters using the geometric characteristics of the flow channel. For this, a set of experimentally measured quasi-invariant anatomical marks was used, which static and dynamic parameters are utterly determined by the structure of the dominant blood jet. Such marks are the position of the embouchures of pulmonary veins and the left atrium auricle, the directions of the trabecular profile on the left ventricle streamlined surface, the dynamic geometry of the mitral and aortic valves, the length and radial elasticity of the aorta, etc. These marks allow a formal localization of the dynamic coordinate system position of a swirling blood flow in the investigated part of the cardiovascular channel and more accurate estimation of the jet structural parameters evolution. Basing on these parameters, a consistent theory of the initiation and evolution of swirling blood jet in the flow channel beginning from the left atrium to the aorta and its main branches has been proposed. The result of the study is a concept, integrating the measured characteristics of the heart and the aorta flow channel (dynamic dimensions, elasticity) and the structural parameters of swirling blood flow. It was shown that flow channel pathological changes significantly affect the flow structure.

In this work, a bow thruster is proposed to be used onboard small and medium-size watercraft, like motor yachts, fishing boats, patrol boats, ocean exploration vessels etc. with conventional or unconventional hull designs including displacement hull, planing hull, catamarans, SWATHs, SES, and so on. As oftentimes the case, a magnetic coupling is employed. Specifically, magnetic coupling is used to transfer torque from a brushless motor’s stator to its rotor through a magnetic field rather than a physical mechanical connection. Such magnetic coupling is very convenient for liquid pumps and as, in our case, propeller systems, since a static, physical barrier can be placed between the stationary and rotating part of the system to separate the fluid from the electrically supplied stator operating in air. Therefore, magnetic couplings preclude the use of shaft seals, which eventually wear out and fail from the sliding of two surfaces against each other. In this work, a system identification process of a rim driven bow thruster is implemented employing data series obtained by tests on a prototype scale model. System Identification leads to a black-box model of the system. The model derived can be extrapolated by grey-box modeling techniques for further design improvements. A control system for the proposed thruster is developed and validated through both computer and hardware-in-the-loop simulation, after its implementation onboard a broadly used industrial Programmable Logic Controller (PLC). The mathematical model of the bow thruster mechanism is developed and the performance is analysed by using Matlab/Simulink.

This paper presents new method in dynamics — the Moving Frame Method (MFM) — and uses it to address a challenge faceing Norwegian shipping. Large offshore renewable energy investments require the use of maintenance boats to keep them in operable conditions. Unfortunately, due to rough seas in some project locations, the transferring of crew members from vessel to turbine or platform is fraught with safety concerns. These concerns can be alleviated by controlling the motion of the transfer vessel. This research studies an add-on stability system for marine vessels to ease the process of offshore platform maintenance and crew member safety. Specifically, this research concerns an internal active system — an active gyroscopic stabilizer — and a more powerful method of theoretical and computational mechanics. This paper derives the equations of motion of a model system equipped with dual gyroscopic stabilizers, using the MFM. The equations of motion are numerically solved to obtain a numerical simulation. The method exploits a variational principle with a restricted variation of the angular velocity. The MFM simplifies dynamics, enables a consistent notation, from 2D to 3D analysis and exploits matrix algebra in lieu of the vector cross product. Finally, in a companion paper to this one, the mathematical model and the numerical simulation is verified with experiments conducted in a large-scale wave tank.

The modern engineering industries rely heavily on the reliable operation of rotating machinery, e.g., steam turbine and gas turbine. These rotating machineries are inevitable to be excited by the unbalance mass forces, the oil film forces and seal forces. Moreover, the turbines installed in an aircraft as well as vessel are also excited by the base vibration. In order to retain the healthy operation and prolong the interval between overhauls, an enormous amount of experimental and theoretical investigations have been focused on the dynamic behaviors of the rotor system. The dynamic characteristics of the rotor system influenced by the single source of vibration, such as unbalance, flowing lubricating oil, sealing medium etc., and combined sources of vibration have also been thoroughly researched. However, the dynamic responses of the rotor-bearing-foundation system subjected to labyrinth seal forces have seldom been studied. Furthermore, the previous analyses of the rotor dynamics mostly were linear. In fact, the fluid film forces are strongly nonlinear functions of the displacement and velocity of the rotor. As a result, the rotordynamics of the turbine is highly nonlinear. It is not accurate enough to be considered from a linear point of view. Applying the energy method, this paper established a dynamic model of the rotor-bearing-foundation-labyrinth seal system. The influences of the geometrical parameters and operating conditions, such as mass eccentricities, inlet pressure and rotational speed etc., on the nonlinear dynamic behaviors of the rotor system are numerically studied. The responses of the same system excited by one side of and both sides of base movement are also comparatively analyzed by means of spectrum cascades, bifurcation diagrams and whirl orbits as well as Poincaré maps.

This companion paper represents the experimental validation of a new mathematical method that models the gyroscopic control of small craft at sea. In light of the development of offshore wind farms, there is a need for stabilizing smaller vessels that transfer crew to and from the wind farms. One way of stabilizing floating vessels is by the use of gyroscopes (inertial spinning disks) mounted on the vessels. The research presented in this paper uses the Moving Frame Method (MFM) as the underlying analytical method. The companion paper introduces the method and provides the mathematical analysis. This paper presents the experimental validation. Tests performed in a wave tank are used to verify the equations obtained by using the MFM. The tests are performed using a scaled model of a floating vessel. The vessel motions are obtained by an inertial measurement unit (IMU). The data received from the IMU and equations obtained by using the MFM calculates appropriate gyroscopic nutation rates to reduce the vessels roll motions. The rates are then applied to the gyroscopes using servo motors. This research demonstrates the power of the MFM. More importantly, it shows how the MFM invites experimental validation tests, as it is fundamentally a 3D analysis, yet open to understanding and use by undergraduates. The authors request that reader review the companion paper previous to this one.

River transportation conveys economic advantages to industry, when it is compared with road transportation. River vessels transport different types of cargoes that are critical for many industrial processes. Watercrafts can suffer different types of mishaps, including sinking and capsizing. The consequences of such events can be costly from the human and economic perspectives. In this context, a major economic consequence can be the closure of any navigation activities in this type of infrastructure. This situation was observed in the Rhine river in 2011, when a river tanker capsized and provoked the closure of the river for some weeks. Based upon the report of this accident, in this paper a simplified model is proposed to analyze such mishap, to reinforce the conclusions conveyed in the report about the contributing factors for this accident. In particular, the crucial effects associated to the dynamic interaction of the liquid cargo and the ship.

Here we observe the spatial and temporal patterns that erosion fronts driven by pulsed radial wall jets develop in double ring arrays of pulse tubes within slurry mixing vessels with curved bottoms. Although erosion of unbounded particle beds driven by individual steady jets has been studied for decades, the patterns developed within mixing vessels as neighboring transient erosion fronts collide and the subsequent relaxation of the particle bed towards the vessel center when the jets stop (i.e., as the pulse tubes refill within mixing vessels) remain incompletely understood. Relaxation here refers to motion of fluidized particle beds that were driven toward the vessel seam by radial wall jets that subsequently return or relax from the seam toward the center of the vessel when the jets turn off. Relaxation does not refer to downward individual or hindered particle settling. Spatial variations in the particle bed due to these relaxing particle beds comprise an important “initial” condition to the mathematical description of the evolution of the jet driven erosion front, and erosion fronts other than the one that expands radially from the pulse tube axis have only recently been described. For example, Bamberger, et al. (2017) [9], recently evaluated five selected cases of erosion patterns found in vessels 15 and 70 inches in diameter with 2:1 semi-elliptical bottoms. A highlight of that study was the discovery of a second type of erosion front that forms at the plane of symmetry between two adjacent pulse tubes. As neighboring radial wall jets collide they form an upwelling sheet of fluid; this second type of erosion front forms immediately beneath this upwelling flow. However, variations in this type of planar erosion front have not been cataloged previously. In this study, we systematically probe the erosion fronts driven by these upwelling sheets in greater detail and evaluate the relaxation of the particle bed to its “initial” condition after the pulse ceases. Variations in the erosion patterns and particle bed relaxation are evaluated as a function of particle concentration, density, and size. This study specifically focusses on video images collected from the 15 inch vessel because it provides distinctive visualization of erosion pattern behavior. We find the upwelling sheets to be more influential on the erosion patterns at lower particle concentrations, making these findings particularly important to low solids concentration vessels. At lower particle concentrations, flow at the base of the plane of symmetry readily erodes particle beds. At higher particle concentrations, piles of unmobilized solids accumulate beneath colliding jets either because the erosion mechanism vanishes or because erosion at the plane of symmetry is slow compared to radial erosion. We also find that the upwelling sheets introduce a flow that drives erosion patterns from outer ring jets toward the vessel center along the curved vessel floor along the plane of symmetry between nozzles. We further find that the rate of particle bed relaxation back toward the vessel center after the pulse ceases may correlate with concentration, particle density, and size. Higher concentrations and particle densities relax faster. The rate at which the entire bed relaxes toward the vessel center is faster near the vessel seam but slows as the relaxing front approaches the vessel center. This paper discusses competing mechanisms to explain these observations, including particle rolling, bed avalanches, gravity driven fluidized bed motion, and suspended particle sedimentation.

In order to understand the behavior of bolted joints and select a right size, type and gasket load combination, a detailed analysis tool is very helpful. However, the modeling and analysis of a bolted joint connection is a complicated, complex process; particularly if multiple parts are considered in the Finite Element (FE) modeling. Analysis results are often sensitive to bolt pre-torque, gasket type, gasket thickness and other challenges of Finite Element (FE) modeling. In addition, often credible and reliable gasket deflection-load data are not readily available. The bolted joint under study was a double-gasket joint with inner gasket leakoff. The joint has leaked on several occasions, sometimes after several years of service due to warmup/cooldown cycling and sometimes immediately after installation and pressurization. A 3-D FE model was developed for assembly of tubesheet, bolt, two inner and outer gaskets, and vessel cover. Different cases were studied by changing gasket load-deflections for different gasket materials, gasket thicknesses and bolt loads. The outcome of the analyses was used to predict the behavior of bolted joints and understand the root cause of leakage. The results provided guidance for choosing the right combination of bolt pre-torque and gasket type.

Floating Production, Storage and Offloading (FPSO) units are floating vessels used by the oil and gas industry offshore for the production and processing of hydrocarbons as well as storage of oil. It is equipped with the required facilities to produce, process, and store produced fluids. Among the equipment on board of the FPSO are pumps used to inject water or pump crude oil. This FPSO is fitted with seven positive displacement pumps powered by diesel engines; three for water injection and four for power fluid. At the exhaust of the driving engines, stainless steel bellows experienced frequent failures on a monthly basis; thereby, incurring a huge financial overburden on operating companies. Therefore, the aim of this paper is to explore the possibility of identifying some remedies to overcome this problem. The paper discusses the root causes of bellow failures attached to the exhaust system of a diesel engine on board of an FPSO. Effect of vibration, temperature, corrosion, and vessel rolling on the bellow structural response were investigated to identify the root causes of failure. A finite element modeling of the problem under study was conducted by taking into account the combined effect of thermo-mechanical loads. It was found that the thermal stress was well below the allowable stress. In addition, vibration analysis of the bellow-engine system revealed that the fundamental frequency of the bellow was way below the engine’s natural frequency. However, it was found that the vessel’s rolling generated an elevated stress that can cause failure of the bellow in a very short period time. The paper also presents some possible solutions to remedy or delay failure from occurring frequently as in this case.

Rapid deployment of marine structures is of growing importance to U.S. naval forces. Surface-based inflatable structures including Rigid Inflatable Boats (RIBs), inflatable causeways and bridging, and launch and recovery systems provide unique solutions for temporary structures during sea-based missions. When performance specifications demand minimal weight and stowage, rapid deployability and temporary rigidity, solutions are limited to inflatable structures constructed of flexible materials. Driven by air pressure, today’s inflatables provide significant load-carrying capacities per unit weight (or stowed volume) utilizing technical textiles, elastomers or “soft” composites. Overloading of inflatable structures produces unique fail-safe behaviors (reversible wrinkling) that allow the structures to assume rigidity and load-carrying capacity upon load removal. Design standards are virtually nonexistent for inflatable structures involving shapes constructed of spheres, beams, arches and most recently flat panels using 3D woven drop-stitch panels. Predictive performance tools (analytical and numerical) for static applications lag significantly behind those for conventional structures. Nonlinear system behaviors (material and geometric), thermo-mechanical coupling and fluid-structure interactions (FSI’s) pose significant challenges when applying existing design tools to inflatable structures. This gap is further exacerbated for dynamic applications as inflatable structures exhibit pressure-dependent natural frequencies and mode shapes. Surface-based structures must be designed with consideration given to operational sea state frequencies and wave periods so that the onset of structural instabilities (wrinkling, buckling) and loss of load-carrying capacities can be prevented. The present research establishes the validity of physics based models using the Ideal Gas Law as an equation of state (EOS) to predict the natural frequencies and corresponding mode shapes of air-inflated drop-stitch fabric panels as functions of inflation pressure. Particular concern is given to the breathing modes for inflation pressures ranging from 5.0 to 30.0 psig. The presence of breathing modes can negatively impact the riding performance of RIBs vessels constructed with drop-stitch fabric hulls by amplification of the panel’s skin separation displacements and vertical accelerations, and are not seen in this material system for the pressures considered. Both numerical and experimental methods are pursued; the results of laboratory modal experiments are used to validate the numerical models. Predicted and experimental natural frequencies and mode shapes are compared and excellent correlation was observed. Increasing inflation pressures produced increasing in-plane and through-thickness normal stresses and modal frequencies of the drop-stitch fabric panels.

COPVs are currently used at NASA to contain high-pressure fluids in propulsion, science experiments and life support applications. These COPVs have a significant weight advantage over all-metal vessels; but, as compared to all-metal vessels, COPVs require unique design, manufacturing, and test requirements. The most significant difference from metal pressure vessel designs is that COPVs involve a much more complex mechanical understanding due to the interplay between the composite overwrap and the inner liner. Often only limited analysis is performed to obtain an initial design, and then the design is refined through number of “build and burst” iterations. However, the cost in material and resources to fabricate multiple test specimens is extremely prohibitive. To avoid these high cost and time for build and burst iterations, FEA is often employed in an attempt to reduce the number of iterations required. FEA process becomes more of a design confirmation effort rather than a design iteration effort. In this research, we aimed to establish a detailed design optimization of a complete COPV through Finite Element simulation.

Beam-like structure is known as one of crucial engineering structures in practical application of aerospace, vessel, civil and machinery. The damages have a great influence on machine performance and may cause a serious threat for security of mechanical structures and systems. Thus it is very significant to identify the damage of beam-like structures for security of mechanical structures and systems. This paper presents a novel application of wavelet finite element method (WFEM) in Lamb wave propagation of beam-like structures. The WFEM, adopting excellent B-spline wavelet on interval (BSWI) basis as approximating functions, has been verified to possess some superiorities for structural dynamic analysis and damage detection. The motion equations of Lamb wave propagation are derived according to Hamilton’s principle and two-dimensional wavelet-based element is constructed by adopting BSWI scaling functions. The damage, which is modeled as open crack with duplicate nodes, is considered in beam-like structures and corresponding damage model is also added in proposed wavelet finite element model. Then central difference method in time domain is employed for wave propagation simulation. Firstly, the validity and accuracy of proposed WFEM are demonstrated on a beam-like structure without crack by comparing with traditional finite element method (FEM) using 2D plane element. What’s more, the obtained velocities of fundamental S 0 and A 0 mode waves are also compared with Lamb theoretical results to verify the validity and accuracy of proposed model once more. Then the wave propagation in beam-like structures with crack are performed and the process and interaction between Lamb wave and damage are analyzed and discussed in detail. The reflected mode wave and converted mode wave for incident wave interacting with crack are also observed in wave motion snapshots. In summary, this paper presents an accurate but simple and effective numerical method for wave propagation of beam-like structures.