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This study uses the critical incident technique to collect and analyze incidents of service failure and success involving a logistics sharing service in which the service providers are individuals. The authors also explore the key factors that affect customer satisfaction, along with the official and ideal recovery strategies. Data is based on interviews with 35 business users in Taiwan in 2017. A card sorting exercise is employed to classify the collected incidents and strategies into categories. The results show that the determinants of success and failure in logistics sharing services include drivers, platform operation, the matching system, and communication. Compensation is the most effective recovery strategy, whereas doing nothing is the least effective. Suggestions based on our results can help managers of the sharing economy to avoid or recover from failures and attain success.

This study evaluated the fatigue strengthening of the foremost transverse hatch coaming stays of 6 sister container vessels of 2650 TEU capacity that suffered fatigue cracking after 1.0 year operation on a North Pacific route. For that, a simplified method was proposed to validate the fatigue strengthening by providing a target hot spot stress reduction factor as a function of the ship lifetime at the crack occurrence. Afterwards, further seakeeping and structural analyses enabled conducting the spectral fatigue analyses of the considered stays’ original and strengthened designs and, by then, to validate the fatigue strengthening of the stays and the simplified approach. The fatigue driving loads, as well as the effect of the long-term operational profiles uncertainties on the fatigue were also discussed on the basis of the spectral fatigue analyses. Finally, crack growth analyses confirmed the criticality of the examined stays with regards to rapid fatigue cracking when the fatigue damage is not properly considered at the design stage.

Background Desmoid tumors (DTs) are rare mesenchymal lesions that can recur repeatedly. When it is feasible, DTs are surgically resected; however, this often results in high recurrence rates. Recently, treatment with PF-03084014, a potent γ-secretase inhibitor, has been shown to have antitumor activity in several tumor types by affecting the WNT/β-catenin pathway. Consequently, Notch pathway inhibition by PF-03084014 might be a promising approach for DT treatment. Methods The expression of Notch pathway components was analyzed in DT tissues and cell strains with immunohistochemistry and Western blotting, respectively. A panel of DT cell strains was exposed to PF-03084014 and evaluated for cell proliferation. Antitumor effects were assessed via cell cycle, apoptosis, and migration and invasion analysis. Cells treated with PF-03084014 were characterized with a gene array analysis combined with Ingenuity Pathway Analysis. Results The results showed that Notch pathway components were expressed at different levels in DTs. Hes1 (Hes Family BHLH Transcription Factor 1) was overexpressed in DT tumors versus dermal scar tissue, and PF-03084014 caused significant decreases in Notch intracellular domain and Hes1 expression in DT cell strains. PF-03084014 decreased DT cell migration and invasion and also caused cell growth inhibition in DT cell strains, most likely through cell cycle arrest. Gene array analysis combined with Ingenuity Pathway Analysis showed that Wnt1-inducible signaling pathway protein 2 possibly regulated Notch and WNT pathways after treatment with PF-03084014 through integrin. Conclusion Our findings suggest that the Notch pathway is an important DT therapeutic target. Furthermore, PF-03084014 has significant antitumor activity against DTs, and it may be an alternative strategy for DT treatment.

Structural analysis of FRP wind turbine blades must take into account phenomena associated with aerodynamics as well as fluid–structure coupling, because aerodynamic loading causes blades to bend mostly in the flapwise direction, and simultaneously causes foil sections to rotate to create new fluid fields around the foils. This study developed an analytical process for calculating fluid–structure interaction, while considering the effects of aerodynamic pressure and finite element analysis in the design of wind turbine blades. In addition, we calculated turbine power efficiency to evaluate the results of fluid–structure interaction displaying approximately power capacity loss of 17% at a wind speed of 25 m/s, and proposed three feasible improvements to enhance the performance of wind turbines. The presented study provided a comprehensible means by which to interpret changes in the aeroelastic response of blades, and was helpful to modify the original wind turbine model.

A sandwich assembly with core material enhances the bending stiffness of a structure and achieves lightweight requirements. Resin flowing behavior inside a sandwich assembly consisting of fiber layers and a segmented core is more complex than that for a fibrous assembly consisting of only fiber layers. This study presents infusion experiments on sandwich assemblies in the VARTM process, and compares the results to simulations from a 3D sandwich model including circular pipe elements to substitute for core grooves. Using the concepts of equivalent thickness to define the porosity of a sandwich assembly and porous space helps derive permeability trends and predictive equations to simplify permeability calculation. The deck infusing experiment in this study not only proves the permeability rationality of a sandwich assembly, but also provides concepts and suggestions for infusion arrangements. Consequently, the permeant characteristics in the sandwich assembly are applicable to manufacturing sandwich structures with good saturation.

With experiments, this study discussed the characteristics of composite curvature shells with constrained layered damping (CLD) subjected to low-velocity impact as well as compared the reactions of the curvature shells with/without CLD. In addition to the experiments, this study proposed the quasi-static simulation, which could rapidly obtain the results with different impact velocities and drift masses with the force–displacement curve of static crushing test, to receive the results subjected to low-velocity impact under various impact conditions. The shell specimens were laminated with two stacking sequences collocating two different drift masses and impact velocities. The experiment of low-velocity impact applied Dynatup-GRC8250 and IDA system to measure the impact force at various time-points in the process of impact and, with the conservation of energy, changes of velocity and strain energy in the impact process could be calculated with the initial velocity of the impact. Finally, the quasi-static simulations were compared with the experiments to verify the accuracy of simulations, and results were found satisfactory.

This paper demonstrates the experimental result of changeable pitch propellers in composite material. The use of this composite material is to apply its characteristic of bend-twist coupling; this characteristic is applied to better performance design requirements of the propeller. Two stacking sequences are considered: the first one is a quasi isotropic sequence, while the second one is an optimum sequence obtained using a genetic algorithm. Experiments are designed considering two original propellers manufactured by the first and the second stacking sequence, respectively, and a pre-deformed propeller with the second sequence. Experimental results correspond to the same trend as the calculations and confirm the method of optimization.

This investigation presents a quasi-static simulation method that adopts energy conservation and the results from the static crush to simulate the impact behavior of carbon-epoxy composite laminate plates. These plates consist of adhered visco-elastic material, and formed constrained layered damped (CLD) components. The damping force is considered in the quasi-static simulation. Comparison with experimental results indicates that the proposed method yields accurate results and produces significant saving in computing resources.

Plate and shell specimens were formed from carbon–epoxy prepregs. Then, attaching 3 M damping foil SJ-2552 to specimens formed constrained layered damped (CLD) components with sandwich-like structures. A steel indentor was used to compress the plate and shell specimens until they completely collapsed. The crushing strength of the CLD components is examined experimentally, and the finite element software ABAQUS is used to simulate the experimental crushing behavior using the user-defined material (UMAT) subroutine. UMAT allows users to define the progressive stiffness modification and analyze the fracturing of composite components. The ultimate strengths of the CLD components are accurately estimated using the UMAT, and the failure observed in the experiments closely corresponds to that in the numerical simulations.

The hull of high performance submarines must resist underwater shock loading due to exploding torpedoes or depth bombs. An underwater shock involving an initial shock wave and successive bubble pulsating waves is so complex that a theoretical technique for deriving shock pressure distribution is required for improving simulation efficiency. Complete shock loading is obtained theoretically in this work, and responses of a submarine pressure hull are calculated using ABAQUS USA (Underwater Shock Analysis) codes. In the long run, this deflection and stress data will assist in examining the structural arrangement of the submarine pressure hull.

The material and ply angles of a fiber-reinforced plastic (FRP) rotor blade of a helicopter are optimized using a genetic algorithm (GA) with local search. The variation of the structural stiffness with material and ply angle is investigated. The aim of the optimization is to find an optimal stacking sequence that minimizes twist deformation. An optimum rotor blade is obtained using the ply angles as variables; failure, natural frequency, and minimum moment of inertia are used to constrain the optimization. The GA is employed as an optimization tool. A simplified local search is implemented in the final stage of optimization to reduce the searching time.

This study examines the progressive failure of marine glass fiberreinforced plastic (GFRP) laminates subjected to out-of-plane water pressure. First, experimental data concerning laminates that consist of a single type of fiber are used to establish the finite element model by separating the section into fiber layers and matrix layers. After a suitable failure criterion has been specified and the stiffness modification factor of different materials obtained experimentally, a numerical model is used to simulate the failure behavior of marine GFRP laminates. This numerical model is then applied to analyze the failure of GFRP ship bottom structures under water pressure. The water pressure failure experiment is designed to verify the numerical results. The experimental system includes a watertight cabin, which comprises the wall of the fixture, the specimen, and a movable piston, filled with water. Then, the water pressure is increased by moving the piston to compress the water-sealed zone, until the specimen reaches ultimate failure. After the numerical model has been validated, the abilities of testing and analyzing the failure behavior of laminates under static water pressure are established. More information is presented about the capacity to resist out-of-plane water pressure, the proper use of the material, and improving the efficiency of the design.

This work investigates the impact behavior of carbon-epoxy composite-laminated shells with three different curvatures. For the low-velocity impact cases, a quasi-static method is introduced to reduce the need for dynamic approaches. The static crushing information (force-displacement data) of the shell is critical to the quasi-static simulation. Based on the crushing data extracted from experiments or numerical simulations, numerous dynamic impact results for distinct impactor masses and velocities can be obtained immediately from a single static result, as long as these impacts are classified as low-velocity conditions. Static experiments and simulations are always more effective than dynamic ones. This investigation concludes that the quasi-static method delivers excellent exactitude, provided the static force-displacement data, the dominator, are accurately acquired.

Interest in the application of genetic algorithms (GA) to the stacking sequence of composite laminates has grown in recent years. However, the huge calculation time of GA is a major problem for designers. In this study, a local improvement is inserted into a standard GA, and the real calculation, by finite element analysis (FEA) for example, required in the local search is replaced by a regression model. Accordingly, the improved GA converges much sooner than a standard GA and the calculation time is greatly reduced. The regression analysis applies chosen trigonometric functions as base functions, and estimates objective function values accurately using only few sample points. The GA with local improvement is then applied to a sandwich plate and composite propeller, the amount of calculation is reduced by over half.

The crush behavior of carbon-epoxy composite laminated shells with three different curvatures is investigated. The FEM package ABAQUS and the user-defined material subroutine (UMAT) based on the concept of progressive stiffness degradation were employed to simulate crushing until the specimens totally collapsed. The 2-D delamination propagation proposed by Davies et al. is considered to be an additional failure mechanism for some curved shells whose contact crushing forces are large. The ultimate strengths of the shells are accurately predicted by the presented method, and all experimental cases are accurately simulated and explained.

Traditional propellers are made of high-stiffness metal material. They deform only slightly and are usually designed to work at a constant speed, operating at reduced efficiency at other speeds. This research designs a composite propeller that operates over a wider range of speeds. The deformation of propeller is determined by orientating fibers to produce propellers that are more efficient than those made of metal. First, structural and fluid dynamic calculations are performed to determine the deformation, the fluid pressure, and the performance of the propeller. An optimizing genetic algorithm is then used to determine the best stacking sequence of the propeller; however, if the optimal stacking sequence does not outperform a metal propeller, a predeformed design is then used to solve this problem. A smallest pitch stacking sequence is obtained using a genetic algorithm first, and then the propeller is displaced in the opposite direction to form a predeformed propeller. The predeformed propelle...

Some optimization methods have recently been developed to deal with discrete variable problems such as that involving the ply angles and stacking sequence of composite laminates. However, much calculation is still required for the algorithms. A regression equation of the response surface would allow the finite element analysis to be replaced with the regression equation, saving much time in optimization design. The response surface of composite laminated structures is estimated using regression analysis in this study. The information of the surface can be obtained quickly and accurately. Usually, simple polynomials are used as base functions in regression, but the results obtained unsatisfactory in this work. Considering the periodic and directional property of the design variables (ply angles), trigonometric functions are used as base functions in regression and they fit the surface very well. According to the characteristics of ply angle and trigonometric function, the value of variable can be chosen to smoothen the response surface, greatly increasing the accuracy of the regression. This study first establishes the regression procedure, and then applies it to examples of a marine propeller and a rotor wing. The regression is used with a genetic algorithm to search for optimum ply angles in the examples, saving much time while maintaining accuracy.

A steel impactor was used in drop tests to impact composite laminated plates constructed using carbon-epoxy prepregs. The impact force and strain histories were recorded as well. Damage incurred from a low-velocity impact much closely resembled that from static crushing. This investigation creates a user-defined material subroutine (UMAT) of the FEM software ABAQUS, using our method of stiffness progressive modification, such that extreme failure is accurately simulated until the plates are thoroughly crushed. Using the results from the static crush simulation and the aspect of energy conservation, the dynamic impact force given with different impactor masses and initial velocities can be rapidly predicted while making significant savings in computing resources.

Plate specimens were formed from carbon-epoxy prepregs. Thereafter a steel indentor was used to compress the specimens, with the reaction forces were recorded until the plates thoroughly collapsed. The FEM software, ABAQUS, was employed to simulate the crushing of the plates. This investigation creates a user-defined material subroutine to enhance the damage simulation which includes Hashing and Yeh failure criteria. The ultimate strengths of the plates are accurately estimated using the present method of progressive stiffness modification, and the failure observed in experiments closely corresponds to that of the numerical simulations.

Marine glass fiber-reinforced plastic (GFRP) laminates, such as M-R laminates, have various tensile and flexural mechanical properties. This phenomenon holds not only for laminates composed of various fibers, but also for laminates composed of a single type fiber. Therefore, this paper will use both a theoretical and a numerical model to calculate the tensile and flexural Young's moduli, to elucidate the mechanism that explains the discrepancy. According to this, the numerical model of GFRP laminates made from a single type of fiber can be established from the data of material experiments, which are easily performed in the laboratory. The mechanical properties of laminates composed of different types of fibers can then be predicted precisely by this numerical model without further material experiments.

The present study employs a numerical approach to investigate the post-buckling behavior of laminates connected by rivets. In order to reduce the calculation time, the rivets are replaced with springs, while the stiffness of the springs is induced from the study that analyzes the bending behavior and the interaction between the rivet and the laminate. The finite element software ABAQUS is used to inspect the post-buckling behavior of composite laminates connected by rivets. Several parameters are considered like the stacking sequence, the arrangement of the rivets, and the span between the stiffener. In all these cases, springs can fully present the behavior around the rivets. Finally, the validity of this method is verified by experiment.

A nonlinear finite element code, DELAM3D, with a three-dimensional layered solid element based on the updated Lagragian formulation, is developed to simulate the compressive response of a laminated composite plate with multiple delaminations. An analytical model is established to characterize the mechanical behaviors such as postbuckling, contact of the delaminating interface, delamination growth and fiber-matrix failure. Double cantilever beam (DCB) and end notched flexure (ENF) tests, with T300/976 graphite/epoxy, are performed to verify the energy release rate of the material. Experiments with various crack numbers, sizes, locations and layer orientations have been conducted and compared with the numerical solution. Good agreement is expected.

An activated antiroll tank system design for ship roll reduction was investigated. Considering the dynamics of the ship motion, tank flow, and variable-pitch impeller, a control law is derived based on optimal control and estimation theory. Finally, a series of numerical computations for a 1174 tonne ship without an antiroll tank system, with a passive tank system, and with the proposed activated antiroll tank system is performed. The results show that the proposed activated tank system has superior antiroll properties for free rolling, regular, and irregular sea loads to the passive tank system. In addition, this design has a very low sensitivity to variations in ship and tank dynamics. It shows that the proposed system is reliable and valid for practical use.

The low-velocity impact behavior of sandwich beam subjected to the cylindrical impactor is investigated numerically. Finite element software ABAQUS is used, and maximum stress failure criterion and a modified stiffness degradation method are adopted to analyze the failure behavior of sandwich beam, including initiation of failure, and failure modes. The two failure modes ; shear cracks in foam (Mode I), and crushed in core and damage in the top face sheets right underneath the impactor (Mode II) can be simulated well. At the range of impact velocity on this study, it can be shown that the the dynamic responses of sandwich beam are nearly quasi-static, therefore, the dynamic behavior of sandwich beam such as impact force history can be approximately obtained from static results.

An active bow absorber for vibration reduction of hull girders is presented. In this investigation, the chain locker of ships is designed as the tuned mass of the absorber, which is driven by a hydraulic system. Since the chain locker is very heavy, the absorber will have a high efficiency for vibration reduction. Including the dynamics of the hydraulic system, the control law of the absorber is derived basing on the optimal control and optimum estimation theory. Finally, frequency and time response are considered for a bulk carrier to understand the feasibility of this design. From the simulations, we find the bow absorber is highly effective for vibration reduction of hull girder due to main engine excitation, especially for the lower frequency mode, such as v-2, v-3 and v-4 modes. The required hydraulic force and the displacement of the actuator for reducing the resonance exciting are reasonable. The results also show the effect of vibration suppression by the bow absorber is similar to that by the stern absorber even for the excitation in stern.

The objective of this paper is to analyze the structural dynamic buckling strength of bow structure of a 1,700 TEU container vessel subjected to slamming impact force using finite element method (FEM). The slamming impact load formula suggested by Lloyd’s Register (LR) is used to assess the reliable value of impact force acting on the bow structure. To determine the critical buckling strength of a structure, two methods were developed—a one-time thickness deformation method and a buckling failure method—and are suggested to be used in the future as an industry standard. Various reasons for the causes of structure buckling damage are discussed, including magnitude of impact load, impact duration time and wave impact pattern. The result demonstrates that impact force integration under impact force-time curve is one of the crucial factors for structure dynamic buckling assessment. In the consideration of structure design optimization, this study compares efficient solutions to increase the structure buckling strength. Additionally, this study provides a clear picture of structure dynamic buckling behavior under variant impact force; moreover, it offers the designer solutions to prevent the structure from buckling damage.Copyright © 2012 by ASME

The reduction of hull girder whipping in slamming by an active control system is investigated. Under the consideration of hull flexibility, a mathematical formulation is developed for the whipping of a hull, subject to slamming, and including an active vibration control system consisting of a tuned mass and hydraulic servo system. Using the optimal theory, the control law of the active system is determined. In addition, a closed-loop estimator is introduced to estimate the distribution of hull motion, which is required to compute the actuator output of the active system. Finally, a numerical example of an application to a 205-ton high-speed craft is described. The results show that the whipping will be reduced significantly. The whipping acceleration and induced stress in particular are reduced more than 95% within 2 sec by this scheme.

The impact behavior of composite sandwich panels subjected to a cylindrical impactor is investigated numerically and experimentally. Three kinds of facesheets and two different core densities of sandwich panels are considered in the impact analysis. During the experiment, the impact force and strain history are measured, and the failure is inspected by visual observations. The experimental results show that the impact behavior is mainly controlled by core material. The ABAQUS finite element software is used to analyze the impact responses of sandwich panels. Because of line load conditions, the sandwich panels impacted by the cylindrical impactor is modeled as a 2-D plane strain problem. The numerical results of impact force and strain history are compared with those measured in experiment, it is shown that the experimental results are in good agreement with the finite element solutions. Further, the stresses of sandwich panels are examined. The maximum stress failure criterion is used to estimate the fracture initiation of sandwich panels. Then the experimental and numerical results are compared and discussed.

Since the response of a panel to moving impact pressure has been shown to differ widely from that to stationary uniform impact pressure. Therefore, before we can clarify the dynamic effect of slamming pressure upon the bottom plate of a high speed craft, a more thoughtful investigation into slamming pressure must be performed, not only the peak values but also the spatial distribution and temporal variation of the water pressure on bottom while travelling in waves.In this paper, a series of test in waves was carried out to measure heave and pitch, acceleration at C. G. and bow, and water pressure at 17 points located on the bottom of a hard chine type model. The time histories of water pressure recorded were compared to the results of the theoretical simulation, which is principally based on a nonlinear strip synthesis. Although the agreement of peak values of impact pressure is less satisfactory, the present theory was confirmed to be a useful method to obtain an overall description of the spatial distribution and temporal variation of the water pressure acting on the bottom of a high speed craft in head sea.

A combined numerical and experimental study is conducted to investigate the failure behaviour of bolted connections in vessel made of GFRP laminates. An incremental 3D FEM code, based on the progressive damage model, is developed for determining the stress distributions, damage propagation and ultimate bolted joint strengths of the FRP laminates with different stacking sequences and degrees of lateral clamping. Next, the bearing strength model test is performed to investigate the failure behaviour of the S-500 glass/polyester laminate specimens. The results show that the stacking sequence significantly affects the interlaminar stress concentration on the hole boundary as well as the failure behaviour of pin joint in GFRP laminate. Furthermore, the introduction of a suitable lateral clamping generally improves the normal interlaminar stress state at a bolted joint and also increases the initial delamination strength as well as the ultimate strength of bolted connections in GFRP laminates.

An investigation of vibration reduction at the top of the mast by active control system is presented. Two typical external excitations, impact and random dynamic load, are considered. For each type of load, a cost function is defined and its optimal law is solved. Besides, an active stay system is designed to offer an active force on the mast.By comparing the direct stiffness increment and fixed stay auxiliary methods, it is shown that the active stay system has the fastest decay property among these methods for impact induced motion. For random exciting load, it has superior effect of peak suppressed in spectral density response than other two methods and its standard variations much lower than other cases compared. In addition, the lateral translation and slope accelerations at the top of the mast reduced by the active stay system is also the most effective. Numerical examples demonstrate that the active stay system with optimal law is a powerful and feasible scheme for mast vibration reduction.

A study of the impact damage of laminated plates and cylindrical shells was conducted by experimental and numerical analysis. The curvature effect on the impact damage of composites was investigated. Laminating sequences of [0°5/90°5/0°5] and [90°5/0° 5/90°5 were considered. Detailed presentation of impact damage was provided through photographs and schematic diagrams. It is found that there are matrix cracks in the lower layer and delamination in the lower interface in plates, while the fiber crack in the upper layer, shear crack in the middle layer and delamination in the upper and lower interfaces are observed in cylindrical shells. A numerical analysis to predict and explain the crack initiation of laminated plates and cylindrical shells was also established.

The dynamic responses of composite laminated plates and shells due to inelastic impact are analyzed by using the finite element method. In the inelastic impact analysis, the structure is considered to be elastic, but the loading is idealized as inelastic. A modified isoparametric linear shell element, in which the shear deformation and rotatory inertia are taken into account, together with the theory of conservation of momentum and Newmark time integration method are used to solve the set of finite element equations. The influences of shell curvature on the impact response are investigated and discussed. The impact experiments are performed and the experimental results are in good agreement with the finite element solutions.

The compressive strength of the bottom girder of ultra large tankers are studied in the present paper. The size increase of tankers results in the relative decrease of plate thickness to other dimensions. In order to provide a design guideline against surmised buckling, the parallel part models of the bottom girder scaled 1/8.7 are experimented by assuming full load condition and the finite strip method is employed for numerical investigation.The following phenomena are observed from experiments and numerical results.When the spacing of the tripping brackets L is less than the critical length Lcr given by Eq. (6), the local buckling of the face bar occurs in accordance to the elastic buckling of the web panel. The lateral buckling is observed for larger spacing. When the local buckling is dominant, the ultimate strength does not depend on the spacing of the tripping brackets. And the initial imperfection of the face bar decreases the ultimate strength, while elastic buckling value of the web panel and the imperfection of the panel do not have pronounced effects. The necessary stiffness of the tripping brackets to prevent lateral buckling may be estimated as in Eq. (16) for the case L>Lcr.

The present paper investigates the ultimate compressive strength of a simply-supported wide panel reinforced longitudinally by multiple stiffeners. It was clarified in the previous paper that in the case of one stiffener, the ultimate behaviors depend upon the equivalent flexural rigidity γe of the stiffener and they are classified in the three modes by the specific values of γe : γ1 and γ2. The same tendencies are observied in the case of multiply stiffened panels ; weak stiffeners (γe γ2) are effective to be panel breakers and only local deformations are dominent even at the ultimate strength. If γ1

The buckling behavior of composite laminated square plates is analyzed with the aid of the finite-element method in which a modified isoparametric linear shell element is used. The in-plane and bending displacements are used together in the formulation of the finite-element method in the case of asymmetric laminates. A new method of modifying the constitutive law of composite materials to circumvent the shear-lock effect is also proposed. This new method has the useful property of removing the shear-lock effect in the case of very thin plates. Composite laminates of symmetric and asymmetric stacking sequences, with and without a central circular hole are analyzed. Using the developed program, various laminated cases are analyzed and discussed. The present results show an improvement over those found analytically when compared with experimental results for asymmetric laminates.

The buckling behavior of orthotropic square plate, either with or without a central circular hole, is analyzed with the aid of the finite element method. Materials with different degrees of orthotropy are examined. Both uniaxial and biaxial compression are considered for various boundary conditions. For highly orthotropic material under uniaxial or biaxial compression in the weaker direction, there is a tendency for the lowest buckling mode not to be a single half-wave. It is found that the first buckling mode may be two or three half-waves, depending on the degrees of orthotropy as well as boundary conditions. The characteristics of buckling strength and mode shape of orthotropic plates with central circular holes are presented and discussed in this paper.

It is reported that several cargo ships have suffered from buckling failures of deck or bottom plates stiffened transversely. The ultimate compressive strength of rectangular plates is studied by analyzing a simplified model which clarifies the effects of yielding on the strength.Approximate formulas for prediction of the buckling strength are proposed in terms of the aspect ratio and the ratios of yield stress to elastic buckling stress and initial deflection to thickness. The accuracy of the formulas is verified by the detailed analysis using the combined technique of the finite-element and energy methods.

In previous papers, the authors presented a method for calculating vertical motions and vertical wave loads for a high-speed craft of medium size by treating the craft as a rigid body. In this paper, calculations for both rigid and elastic representations are presented for an existing large-sized high speed craft. Tests were performed to measure the vertical motions of two differently-scaled wood models. Still other tests measured the distribution of vertical bending moment along the ship's length of an elastic backbone model. The theoretical predictions are compared with the experimental results and with the experimental conclusions of other researchers. The comparison shows the two theoretical methods to be accurate enough for practical application.

This paper is to analyze the instability of plate structure subjected to in‐plane periodic forces. By using the finite element method, the regions of dynamic instability of beam, plate, plate with a hole, and stiffened plate are analyzed. These analyses can be used as a reference in the design of plate structure under dynamic forces. The isoparameter element used in this paper takes account of transverse shear deformation. It has the advantage of being quite versatile. The results are in good agreement with those in other literature.

This paper presents a computer program based on finite element method for elastoplastic buckling strength analysis of plate structures. To deal with the material nonlinearity problem, this program applies linearization technique at each loading increment. And the amount of loading increment at each stage is to make one element yield at a time. So by this process we can trace the plastic zone developed during elastoplastic buckling. One outstanding characteristics of this program is that by employing a variant gaussian elimination associated with Sturm sequences property, it eliminates the need of solving the buckling eigenvalue problem at each increment loading stage that is associated with the usual solution techniques. The validity of this program is varified by comparing its numerical results with theoretical and experimental ones.