Load environments

Variations in a produet s material properties, serviee loads, environment and use typieally lead to random failures over the most protraeted period of the produet s expeeted life-eyele. During the eonditions of use, environmental and serviee variations give rise to temporary overloads or transients eausing failures, although some failures are also eaused by human related events sueh as installation and operation errors rather than by any intrinsie property of the produet s eomponents (Klit et al., 1993). Variability, therefore, is also the souree of unreliability in a produet (Carter, 1997). However, it is evident that if produet reliability is determined during the design proeess, subsequent manufaeturing, assembly and delivery of the system will eertainly not improve upon this inherent reliability level (Kapur and Lamberson, 1977). 

Material behavior have many classifications. Examples are (1) creep, and relaxation behavior with a primary load environment of high or moderate temperatures (2) fatigue, viscoelastic, and elastic range vibration or impact (3) fluidlike flow, as a solid to a gas, which is a very high velocity or hypervelocity impact and (4) crack propagation and environmental embrittlement, as well as ductile and brittle fractures. 

Li, Z., and Bowman, R. S. (1998). Sorption of perchloroethylene by surfactant-modified zeolite as controlled by surfactant loading. Environ. Sci. Technol., 32, 2278-2282. 

Advanced composites is a term that has come to describe materials that are used for the most demanding applications, such as aircraft, having properties considerably superior to those of conventional composites and much like metals. These materials are engineered from high-performance resins and fibers. The construction and orientation of the fibers are predetermined to meet specific design requirements. Advanced composite structures are usually manufactured in specific shapes. An advanced composite can be tailored so that the directional dependence of strength and stiffness matches that of the loading environment. 

Fisher, M. M. and K. R. Reddy. 2001. Phosphorus flux from wetland soils affected by long-term nutrient loading. / Environ. Qual. 30 261-271. 

Kemp, P.D., Cavallaro, J.F., and Hastings, D.N. 1995. Effects of carbodiimide crosslinking and load environment on the remodeling of collagen scaffolds. Tissue Eng. 1 71-79. 

Study shape, dimensions, structural loads, environments, government/industry, etc. 

Stress Shielding. Beyond the traditional biocompatibility issues, hard tissue biomaterials must also be designed to minimize a phenomenon known as stress shielding. Due to the response of bone remodeling to the loading environment, as described by Wolffs law, it is important to maintain the stress levels in bone as close to the preimplant state as possible. When an implant is in parallel with bone, such as in a bone plate or a hip stem, the engineered material takes a portion of the load— which then reduces the load, and as a result, the stress, in the remaining bone. When the implant and bone are sufficiently well bonded, it can be assumed that the materials deform to the same extent and therefore experience the same strain. In this isostrain condition, the stress in one of the components of a two-phase composite can be calculated from the equation ... 

The owner of the structure should be provided with a detailed programme which will cover any checks and maintenance that may be required. It should detail suitable repairs that may be used in the event of damage as well as routine work such as the replacement of surface coatings. In addition it should state clearly the use for which the structure is intended, the loadings, environment, etc., so that the necessary corrective or remedial action can be taken in the case of misuse. 

Although the terms testing and characterization are used interchangeably to describe evaluation of various properties of plastics, there is a subtle difference between the two terms. Characterization often refers to evaluation of the molecular or structural characteristics of plastics while testing is used to refer to evaluation of behavior of plastics in response to the applied external loads, environment, etc. 

Applied Load, Environment, and Time as External Determinants of Ceramic Hardness... 

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