Impact Behavior of Liquid Crystalline Polymers

2012 ◽  
Author(s):  
Anil Saigal ◽  
Dan Ward ◽  
Michael A. Zimmerman
Keyword(s):  
Impact Energy ◽  
Liquid Crystalline ◽  
Impact Load ◽  
Liquid Crystalline Polymers ◽  
Impact Behavior ◽  
Crystalline Polymers ◽  
Packing Pressure ◽  
Degree Of Orientation ◽  
High Degree ◽  
The Impact

Liquid crystalline polymers have the advantage of achieving desirable mechanical properties at a competitive cost. They are composed of molecular chains that are highly oriented and tightly packed at temperatures above and below its melting point. This high degree of orientation has the following advantages: ease of processing, high mechanical strength at extreme temperatures, and resistance to mostly all chemicals, weathering, radiation, and burning. On the other hand, this high degree of orientation causes liquid crystalline polymers to have low impact strength as well as an uneven amount of shrinkage prior to molding. The objective of this study is to determine the effects of injection-molding parameters on the impact behavior of liquid crystalline polymers, in an attempt to improve and understand the processing of the material. The conditions to be tested are as follows: fill speed, initial mold temperature, and packing pressure. The impact tester used for this research was an Instron Dynatup tester. Based on the data, it is apparent that fill speed is the greatest determining factor for optimizing the impact energy of the injection-molded liquid crystalline polymers followed by high packing pressure. In addition, even though the nature of the impact energy curves for LCPs and materials such as Delrin are similar, the impact load curves as a function of time are significantly different. This can be attributed to the layered structure of LCP samples.

The Structural Impact Characteristics of Indonesian Railway Vehicle

2004 ◽  
Vol 261-263 ◽  
pp. 337-344 ◽  
Author(s):  
Ign Wiratmaja Puja ◽  
T. Hardono ◽  
Khalid ◽  
M.F. Adziman
Keyword(s):  
Impact Energy ◽  
Impact Load ◽  
Rigid Wall ◽  
Impact Behavior ◽  
Railway Vehicle ◽  
Railway Transportation ◽  
Passenger Cars ◽  
Vehicle Structure ◽  
Structural Impact ◽  
The Impact

The Indonesian railway transportation has adventages in term of capacity, efficiency, trafic, and safety compared to the other types of land transportations. At present, the Indonesian Railway Company has 519 locomotives, and 1643 passenger cars, that transport about 184 million man-trip each year[1,2]. Unfortunately, the rate of train collisions in Indonesian railway system was very high. In the last ten years, 2352 train accidents have happened which claimed 997 lives and left 2638 people injured. The record shows that 110 of those accidents were train to train collisions[1]. This paper consider the structural impact behavior of Indonesian passenger railway car subject to collision forces. This characteristic is very important parameter for passenger protection during the course of collision[3-5]. The vehicle structure should be able to absorb the huge impact energy or impact force to ensure the passenger safety[6-9]. The impact energy of cars-train is evaluated using the principle of multibody dynamics[10,11]. The vehicle structure under impact load is analyzed using the finite element method. The principal of symmetry is adopted, so the collision scene could be simulated as collision between the vehicle with a rigid wall. The analysis result shows that the structure is collapse at the passenger area (saloon) which is in agreement with the real collision. Modification is proposed to protect the passenger area by introducing crush zone area and impact energy absorber.

scholarly journals Influence of Voids Ratio on Impact Behavior of Circular Ferrocement Slabs

2019 ◽  
Vol 5 (1) ◽  
pp. 117
Author(s):  
Muyasser M. Jomaah ◽  
Muna Zead Baraa
Keyword(s):  
Impact Energy ◽  
Structural Strength ◽  
Impact Load ◽  
Low Cost ◽  
Load Test ◽  
Wire Mesh ◽  
Impact Behavior ◽  
Experimental Program ◽  
Test Results ◽  
The Impact

The objective of using materials is to fully utilize the properties of these materials in order to obtain the best performance of the structure. The merits of material are based on many factors like, workability, structural strength, durability and low cost. Ferrocement is an excellent construction system. This paper studies the behavior of ferrocement circular slabs under impact load. The experimental program include testing four sime fixed supported ferrocement circular slabs of 800mm diameter and 50mm thickness. The Influence of the use of styropor voids was investigated in different ratios (24% and 48%) and a number of wire mesh layers four and six layers. Impact load test results revealed that increasing number of wire mesh from 4 to 6 led to an increase in the impact energy for first crack by (41.991% ,37.62%) respectively when using voids ratio by (24% and 48%) respectively and impact energy for full perforation by (21.7% and 9.94%) respectively when using voids ratio by (24% and 48%) respectively. Ferrocement circular slabs are used in construction fields such as roofs, tanks, manholes, etc.

scholarly journals Parameter Analysis on the Anti-Impact Behavior of Pcfst Columns under Lateral Impact Load

2018 ◽  
Vol 206 ◽  
pp. 01020
Author(s):  
W Xu ◽  
A Z Zhu ◽  
K Gao
Keyword(s):  
Yield Strength ◽  
Impact Energy ◽  
Impact Load ◽  
Parameter Analysis ◽  
Impact Behavior ◽  
Lateral Impact ◽  
Fea Model ◽  
Filling Height ◽  
Concrete Filling ◽  
The Impact

Concrete-filled steel tubular (CFST) structures have been widel y used in civil engineering structures, due to its good behaviors under both static and dynamic loads. In this paper, numerical studies were carried out to investigate the anti-impact behavior of partially concrete-filled steel tubular (PCFST) columns under lateral impact loads. Finite element analysis (FEA) model was established using ABAQUS. To validate the FEA model, the numerical results were compared with experimental results. Moreover, parameter analysis was carried out to further study the anti-impact behaviors of the PCFST columns. The concrete filling height, the impact energy, the impact direction, and the yield strength of steel were the main parameters considered in this study. The dynamic responses under the impact load, including the impact force, the failure mode, and the displacement response, were all analyzed. The results of parameter analysis showed that the anti-impact behaviors of the PCFST columns significantly increased when the concrete filling height or the yield strength of steel increased greatly. The impact energy and direction also greatly affected the anti-impact behaviors of the PCFST columns.

Structure-property relations of liquid crystalline polymers

1987 ◽  
Vol 45 ◽  
pp. 460-463
Author(s):  
Linda C. Sawyer
Keyword(s):  
Solid State ◽  
Liquid Crystalline ◽  
Structural Model ◽  
Crystalline Polymer ◽  
Liquid Crystalline Polymers ◽  
Mechanical Anisotropy ◽  
Structure Property ◽  
Preparation Methods ◽  
Crystalline Polymers ◽  
Extended Chain

Recent liquid crystalline polymer (LCP) research has sought to define structure-property relationships of these complex new materials. The two major types of LCPs, thermotropic and lyotropic LCPs, both exhibit effects of process history on the microstructure frozen into the solid state. The high mechanical anisotropy of the molecules favors formation of complex structures. Microscopy has been used to develop an understanding of these microstructures and to describe them in a fundamental structural model. Preparation methods used include microtomy, etching, fracture and sonication for study by optical and electron microscopy techniques, which have been described for polymers. The model accounts for the macrostructures and microstructures observed in highly oriented fibers and films.Rod-like liquid crystalline polymers produce oriented materials because they have extended chain structures in the solid state. These polymers have found application as high modulus fibers and films with unique properties due to the formation of ordered solutions (lyotropic) or melts (thermotropic) which transform easily into highly oriented, extended chain structures in the solid state.

Factors affecting microstructural scale in liquid crystalline polymers

1990 ◽  
Vol 48 (4) ◽  
pp. 220-221
Author(s):  
Christine M. Dannels ◽  
Christopher Viney
Keyword(s):  
Liquid Crystalline ◽  
Liquid Crystalline Polymers ◽  
Factors Affecting ◽  
Crystalline Polymers ◽  
Thermal Expansion Coefficients ◽  
Low Thermal Expansion ◽  
Lower Viscosity ◽  
Fine Microstructure ◽  
Planar Orientation ◽  
Strength And Stiffness

Processing polymers from the liquid crystalline state offers several advantages compared to processing from conventional fluids. These include: better axial strength and stiffness in fibers, better planar orientation in films, lower viscosity during processing, low solidification shrinkage of injection moldings (thermotropic processing), and low thermal expansion coefficients. However, the compressive strength of the solid is disappointing. Previous efforts to improve this property have focussed on synthesizing stiffer molecules. The effect of microstructural scale has been overlooked, even though its relevance to the mechanical and physical properties of more traditional materials is well established. By analogy with the behavior of metals and ceramics, one would expect a fine microstructure (i..e. a high density of orientational defects) to be desirable.Also, because much microstructural detail in liquid crystalline polymers occurs on a scale close to the wavelength of light, light is scattered on passing through these materials.

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