Ming Hsiang Shih

Developing three-dimensional digital image correlation techniques to detect the surface smoothness of construction materials

A low-cost three-dimensional digital image correlation coefficient method, 3-D DIC equipped with one advanced digital camera and high-speed computer to detect the flatness of plaster of Paris casts is proposed in this research. The test and analysis results show that this proposed method can easily reveal the rugged surface of plaster cast. No matter what the absolute displacement, rotate on z-axis, strain on z-axis and von Mises strain of analysis results are extremely close to the real situation of this test sample. Then, the joint roughness coefficient (JRC) is used to compare the test results of 3-D DIC with the test results of laser scanner. These results indicate that the JRC values measured by laser scanner are very similar to that measured by 3-D DIC. Therefore, the accuracy degree of this 3-D DIC method is high enough for applying it to achieve the three-dimensional surface smoothness of construction material.

Using the Simplified 3D DIC Method to Measure the Deformation of 3D Surface

In recent years, 2D digital image correlation method (DIC) has been widely used in the measurement of plane strain. However, out-of-plane displacement could be induced during the loading and it would affect the measurement accuracy. Thus, a 3D measurement is necessary. This study utilizes a simplified 3D DIC to measure the geometry of an object before and after deformation. Then the finite element concept is involved to determine the strain after deformation. A flat plate specimen with in-plane and out-of-plane displacement is observed. Both 2D and 3D DIC are used to analyze the strain. The results show that using 3D DIC to measure strain is feasible and with a very good accuracy.

Development of a Low-Cost Unmanned Aerial Vehicle Using Mini-Airship Structure for Acquiring Digital Image Platform

In this study, a low-design-cost and long-endurance unmanned aerial vehicle (UAV) based on the simple microcontroller board and mini-airship technique is proposed. Many well developed positioning sensors, such as GPS, 3-axis Gyroscope, Gravity-sensor and Magnetometer are used. In addition, the control model of Proportional-Integral-Derivative controller is applied to accomplish the long endurance purpose. Such a low-cost design has the potential to accelerate the application of UAV in a variety of video monitoring fields.

Development of Digital Imagine Correlation (DIC) Method for Three-Dimensional Rugged Surface of Construction Material

Digital Image Correlation, DIC method is developed a low-cost digital image correlation coefficient method based on advanced digital cameras and high-speed computers. Traditionally, two or more cameras are widely applied for conducting 3-D monitoring. There are numerous parameters need to be accurately calibrated. Therefore, the results of 3-D accuracy are worse than that of 2-D accuracy. The feasibility of a single camera to collect image to analyze the three-dimensional rugged surface of material is proposed in this study. A three-dimensional facial mask-like human makeup test and plaster cast are used to test. The test results reveal that the coordinate error between these two photos of the three-dimensional facial mask-like human makeup test is only 0.002mm and the absolute displacement, rotate on z-axis, strain on z-axis and von Mises strain of analysis results are extremely close to the real surface plaster cast.

Digital Imagine Correlation (DIC) Method for Detecting Crack Development in Construction Materials Subject to Loading

The digital image correlation (DIC) technique is developed for identifying the crack development in brick wall and reinforced concrete beam. This method is tested on brick wall and reinforce concrete beam to evaluate the observation with various strain quantities and mesh sizes. The analysis results reveal that using the von Mises strain field will lead to fine precision of crack observation, and that clearer imagines can be obtained with smaller mesh sizes. This technique is capable of judging crack loading to predict crack occurrences.

Applying Digital Image Correlation Techniques to Measure the Crack Variation of Steel Plate under Tension

Water gate is one of important equipments for arbitrating water supply and maintaining safety of dam. Water gate is made of high tensile strength of steel plate, this kind of steel plate used as constructional material of water gate is weighed for the economical consideration. Steel plate must be cut, welded and rivet to manufacture water gate. Thus, there are some crevices, induced by the defects of material, bad construction, seismic excitation and errors of size, on water gate. This phenomena causes stress concentration, induced high crack increase rate, affect the safety and usage of water gate. In this research, digital image correlation method is developed to measure the mechanics behavior of single steel plate and bi-steel plate with crevices under tension force according to the characteristics of water gate filed test. The test and analysis results of laboratory test reveal that this digital image correlation method can easily indentify the corrosion point on the steel plate. Otherwise, the crack variation of crack tip of steel plate-single steel plate and bi-material steel plate under loadings can be easily identified by the laboratory test.

Evaluation of Cooling Wall System and Phenolic Resin as Thermal Barrier in Buildings

In recent years, thermal barrier technologies have become an important energy-saving for space heating and cooling of residential and commercial buildings in many countries. Building energy efficiency can be improved by implementing either active or passive energy efficient strategies. Improvements to heating, ventilation and air conditioning systems etc. can be categorized as active strategies, whereas, improvements to building envelope elements can be classified under passive strategies. Using cooling wall system and phenolic resin as thermal barrier are one of the effective passive strategies. Cooling wall system is composed of galvanized iron pipes located inside of walls. Fluid flows inside the pipes and then supply constant cooling temperature. In the study, system using of groundwater as renewable energy source for pipes cooling. The groundwater at depth of more than 5 meters below the surface has constant temperature year round. Lower temperature groundwater would cool the pipes of system by heat exchange process to achieve the cooling effect of wall. The phenolic resin is proposed as construction materials to use its thermal insulation property for developing a comfortable living and working indoor environment. The phenolic resin is an environmental friendly material, and an excellent thermal barrier. In this research, cooling wall system and phenolic resin were evaluated to reduce the thermal transfer from sunlight into the buildings, thus reducing the electricity consumption needs for air conditioning of the buildings.

Analysis Accuracy of Digital Image Correlation Technique to Monitor Natural Frequency Response of Building under Dynamic Excitation

Strong typhoon and earthquake seriously threaten the safety of the life and property of the people. A cost-effective and reliable method is proposed to monitor the natural frequency response of building under excitation of external forces based on the applying digital image correlation method, DIC. The analysis accuracy of this dynamic DIC method is tested and verified by comparing with numerical analysis program, accelerometers, ACC and fast Fourier Transform, FFT. The test results reveal that the analysis accuracy of this DIC method near to the ACC and FFT traditional experimental methods. They demonstrate that using this DIC method to detect dynamic response of building under the excitation of external force has high practicability.

Development of Digital Image Correlation Technique to Monitor Structural Damage Based on Natural Frequency as Damage Index

Recently, some serious earthquakes happened in the world and seriously threaten the safety of the life and property of the people. Monitoring and measuring the quakeproof capacity of building need to install high cost sensitive instruments to provide sufficient information. A cost-effective and reliable method based on the applying digital image correlation method, DIC to monitor the natural frequency of building under excitation of earthquake as damage index is proposed in this research. Using DIC to monitor the structural damage based on the natural frequency as damage index can easily detect the structural damage after the excitation of earthquake. Test results reveal that sensitivity of this DIC method is superior to traditional data collected by installed accelerometers, ACC in structure.