Group Members

Here's the group, the research topics, our mentors, and abstracts from our papers

Keith Epstein-Analysis and Optimization of Complex Structures, Professor Yuanxian Gu

The methods of structural analysis and optimization are used by engineers to assist the design of complex structures. Gu and colleagues have developed an analysis and optimization software package called JIFEX that has been used to optimize many structures. This paper discusses the optimization by JIFEX of four standard test problems, and of a racecar chassis for torsional stiffness. The test problem optimizations show that JIFEX obtains the optimal results in a reasonable number of iterations, and the racecar chassis stiffness has been greatly improved without significant weight penalties.

Ti-Jay Erikson-In-situ Ice Data Collection In Liaodong Bay Using Computer Networks, Professor Qian-jin Yue

The expansion of oil and gas extraction within the confines of the Bohai Sea, alongside other maritime endeavors has spurred additional research studies on the interaction of ice and offshore structures in the region. For the purposes of design, analysis and construction of structures, a considerable knowledge of not only the magnitudes but also the different levels of ice forces generated during a continuous crushing of an ice sheet is important. Also of equal importance are ice-induced vibrations, ice extent, thickness, concentration, temperature and velocities, which are all taken into account among many others.
Ice data acquisition in the region has witnessed many processes, notable among which are conventional observations at coastal stations, aircraft reconnaissance, ship surveys and satellite images. However, in this instance we take a look at data collection using computer networks. The concern of this research is to introduce the basic theory of data collection client /server system in Linux Operating system and also upgrade the device driver of the existing computer network used in data collection in the Liaodong Bay of the Bohai Sea using Linux Operating System.

Lu Gan-Numerical Determination of Wave Propagation Over a Submerged Breakwater, Professor Sun Zhao Zhen

A numerical model for the analysis of wave propagation over a submerged breakwater is presented. The complete numerical model estimates the wave motion by use of a boundary element method in two dimensions. In addition, it outputs the elevation of each free-surface nodal points of interest for a given time interval. To validate the numerical model, the results from the model are compared to the results from the physical experiment.

Seth Kassels-Impact of Wave Slamming on Offshore Structures, Professor Yongxue Wang

An experimental and numerical model study on the impacts of ocean wave slamming on offshore horizontal platforms is presented. Data collection of pressures exerted by regular and random waves on the underside of a horizontal platform is discussed. Experimental data is then compared with data calculated through numerical modeling. Numerical study of ocean wave slamming is conducted through the use of a model described by Wang and Ren. Experimentation consists of a model, 1 meter in length, replicating an offshore oil drilling facility, and a 69-meter long wave flume with a water depth of 0.60 meters. Variables in experimentation include, height of the model off calm water level, and wave parameters for both regular and random waves. Impact pressures on horizontal platforms are found to increase in strength as the wave height (H) increases and the strength of the positive pressure is established by the S/H (distance of model of calm water over the wave height) ratio.

Cristina Rhodes-Analysis of Some Factors in the Inverse Viscoelasticity Problem, Professor Haitian Yang

The effect of some factors in evaluating the accuracy of an inverse solution in the identification of viscoelastic parameters and loads is presented. The problem of inverse analysis is of extreme interest mostly to engineering, but not limited to, as it has the ability of evaluating constitutive parameters initially unknown. The stability of the algorithm proposed by Yang is examined. The numerical study evaluates how changing the number of sample points, initial choice of iterative values and number of samples will affect the number of iterations and the constitutive parameters obtained by the algorithm of inverse analysis.

June Shen-Dynamic Ice Force on Vertical Compliant Structures, Professor Qian-jin Yue

Dynamic ice force on structures in cold regions has been studied since the 1960s. Vertical compliant structures in cold regions undergo vibration response due to the movement of ice sheets. Resonant vibration at the structure’s natural frequency is known as lock-in phenomenon. This response has catastrophic effects on structure stability and use of process machinery within structures. A summary of major theories within this field is presented, linking full-scale ice-structure observations with laboratory investigations of ice failure behavior. Test data from the JZ20-2 MS platform located in the Bohai Sea is used to study the dynamic interaction between ice and vertical compliant structures. Special attention is given to proving existence of lock-in and to investigating the ice failure mechanisms that cause this behavior. It is found that lock-in occurs for the relative velocity in which the ice is in the ductile-brittle transition range. A new theory of ice structure interaction is introduced, using wing-crack ice failure mechanism to explain the phenomenon of frequency lock-in.

Darren Spratt-Wave Modeling Using the Improved Boussinesq Equation, Professor Zhili Zou

A numerical model based on higher-order Boussinesq equations is explained and validated for waves passing over a sill. Through the use of the Boussinesq equation small vertical accelerations are represented and waves thereby retain their dispersive properties. The limitation to shallow water (depth <1/10 wave length) is overcome by including higher-order (frequency dispersion) terms. The numerical modeling is performed using Central Finite Difference Scheme. Initial validation is achieved by comparing the model's output to published results. Physical testing is then performed for various wave and sill combinations, and the results are compared vis-à-vis the numerical model. Comparison results demonstrate the importance of the higher-order terms in accurate prediction of waves.