Characterization of starch films containing starch nanoparticles Part 1: Physical and mechanical properties
- Authors: Shi, Aimin , Wang, Li-Jun , Li, Dong , Adhikari, Benu
- Date: 2013
- Type: Text , Journal article
- Relation: Carbohydrate Polymers Vol. 96, no. 2 (2013), p. 593-601
- Full Text: false
- Reviewed:
- Description: We report, for the first time, the preparation method and characteristics of starch films incorporating spray dried and vacuum freeze dried starch nanoparticles. Physical properties of these films such as morphology, crystallinity, water vapor permeability (WVP), opacity, and glass transition temperature (Tg) and mechanical properties (strain versus temperature, strain versus stress, Young's modulus and toughness) were measured. Addition of both starch nanoparticles in starch films increased roughness of surface, lowered degree of crystallinity by 23.5%, WVP by 44% and Tg by 4.3 °C, respectively compared to those of starch-only films. Drying method used in preparation of starch nanoparticles only affected opacity of films. The incorporation of nanoparticles in starch films resulted into denser films due to which the extent of variation of strain with temperature was much lower. The toughness and Young's modulus of films containing both types of starch nanoparticles were lower than those of control films especially at <100 °C. © 2012 Elsevier Ltd. All rights reserved.
- Description: C1
Measuring soil strain using fibre optic sensors
- Authors: Costa, Susanga , Kahandawa, Gayan , Chen, Jian , Xue, Jianfeng
- Date: 2019
- Type: Text , Conference proceedings , Conference paper
- Relation: 8th International Congress on Environmental Geotechnics, ICEG 2018; Hangzhou, China; 28th October-1st November 2018; part of the Environmental Science and Engineering book series p. 43-50
- Full Text:
- Reviewed:
- Description: Monitoring subsurface soil movement is important in many geotechnical engineering applications such as stability of slopes, road embankments and settlement in foundations. Soil displacement measurement is also helpful in understanding the formation of shrinkage cracks. Clay soils undergo shrinkage during drying and experience substantial stresses and strains, which results in shrinkage cracks. This paper presents a novel approach to measure soil strain using Fibre Bragg grating (FBG) sensors. In the experiments described, FBG sensors have been used to investigate the strain development in clay during drying. FBG sensors are fabricated in the core region of specially fabricated single mode low-loss germanium doped silicate optical fibres. The grating is the laser-inscribed region with a periodically varying refractive index, which reflects a specific light wavelength. Due to the applied strain, ε, there is a change in the wavelength which can be measured and is directly proposal to strain. Kaolin clay, mixed with water close to the liquid limit, was allowed to dry under room temperature. The specimens were prepared in thin, long linear shrinkage moulds. FBG sensors were placed inside soil at the centre of the specimen. The strain development during drying underwent four phases moving from compression to tension. An oscillating nature of strain was also observed throughout the drying process. Results obtained are useful to develop analytical solutions to describe stress-strain behavior of drying soil. © Springer Nature Singapore Pte Ltd. 2019.
Mechanical responses of Boeing 747 running on runways
- Authors: Wang, Xing-tao , Chen, Jianfeng , Ye, Guan-bao , Yang, Dong , Xue, Jianfeng
- Date: 2016
- Type: Text , Journal article
- Relation: Jiaotong Yunshu Gongcheng Xuebao/Journal of Traffic and Transportation Engineering Vol. 16, no. 2 (2016), p. 1-9
- Full Text: false
- Reviewed:
- Description: Based on the large amounts of measured strains and deflections of runway pavement at Denver International Airport, the main characteristics of deflections and strains at different positions of pavement were analyzed when Boeing 747 was running on runway, and the load transfer capacities of different joints, the residual deformations and strain rates of pavement at the typical positions were researched. Analysis result shows that the edge and middle of slab have 2 strain peaks respectively, which corresponds with the number of aircraft's main gear axles. The transverse strain (perpendicular to the running direction of aircraft) only has one type, while the longitudinal strain (parallel to the running direction of aircraft) shows 2 times' transformation between tension and compression. The peak-strain recovery between gear axles at the bottom of longitudinal joint edge is significant, its peak strain and peak-strain recovery are 1.2 times and 2.5 times as much as the values at the top of longitudinal joint edge respectively, which means more prone to cracking and fatigue damage. When the aircraft is running, the maximum strain rates occur at the joint, and the maximum tensile and compressive strain rates are 9.1×10-4 s-1and 7.6×10-4 s-1 respectively, and belong to quasi-static strain rate, so their impact on the deformation of concrete slab are ignored. The deflection curves at the slab's middle have 1 peak, but there are 2 peaks at the slab's corner and transverse joint edge. The relative residual deformation at corner of slab is largest, the deformation at the middle of slab is least, the relative residual deformation rate at the corner of slab is 2.60-4.59 times as large as the value at the middle of slab, and compared with other locations, the corner more easily occurs void with base. The load-transferred coefficient of hinged joint is about 1, the load-transferred coefficient of dummy joint is lower compared with hinged joint, the load-transferred characteristic of dummy joint has directionality, but the load-transferred characteristic of hinged joint is non-directional. © 2016, Editorial Department of Journal of Traffic and Transportation Engineering. All right reserved.