Damage cumulative

Cumulative Damage. Pressure vessels may be subjected to a variety of stress cycles during service some of these cycles have ampHtudes below the fatigue (endurance) limit of the material and some have ampHtudes various amounts above it. The simplest and most commonly used method for evaluating the cumulative effect of these various cycles is a linear damage relationship in which it is assumed that, if cycles would produce failure at a... 

When, in addition. Act varies during the lifetime of a component, the approach adopted is to sum the damage according to Miner s Rule of cumulative damage ... 

The musculoskeletal system consists of the muscles, bones, joints, tendons, and ligaments. Disorders related to the musculoskeletal system often are classified by etiology. Acute soft-tissue injuries include strains and sprains of muscles and ligaments. Repeated movements in sports, exercise, work, or activities of daily living may lead to repetitive strain injury, where cumulative damage occurs to the muscles, ligaments, or tendons.1-3 While tendonitis and bursitis can arise from acute injury, more commonly these conditions occur as a result of chronic stress.3,4 Other forms of chronic musculoskeletal pain, such as pain from rheumatoid arthritis (see Chap. 54) or osteoarthritis (see Chap. 55), are discussed elsewhere in this text. 

Surprisingly, however, dyes of the chlorodifluoropyrimidine type readily form a perhydroxide derivative that leads to cumulative damaging effects on dye-fibre bond stability. A comparison between seven different haloheterocyclic systems each attached to the same chromogen (phenylazo H acid) demonstrated several important conclusions [89] ... 

Drugs with different dose-limiting toxicities should be used to avoid cumulative damage to a single organ. 

This section deals with chemical aging and related physical phenomena, such as diffusion and embrittlement. Apart from the chemical problem there is mechanical deterioration which is also related to long term environmental effects, but this was covered briefly in the preceding cumulative damage discussion. 

Lead Azide Less toxic than Sodium Azide due to its lower solubility. Source of toxicity is the azide ion which may cause lowered blood pressure, vertigo, nausea and collapse. Cumulative damage to kidneys and spleen, may bring on fatal convulsions Avoid ingestion, threshold tolerance value not known... 

D.H. Allen et al A cumulative damage model for continuous fiber composite laminates with matrix cracking and interply delaminations. ASTM Sp. Tech. Pub. 972, 57-80 (1988)... 

Alumina (Coors AD-85) were impacted at velocities up to 14.0 m/s. Those specimens impacted above 12.2 m/s failed by complete spall during the second cycle of tension, and possibly due to cumulative damage. Specimens... 

Fig. 42. Fatigue lifetime enhancement relative to the linear cumulative damage rule. The overloads and primary load cycles are selected from loads that would normally lead to craze or shear type of behavior as indicated in the figure...

Fatigue lifetime predictions in polymers therefore cannot be simply determined by a straightforward linear cumulative damage approach. This is especially true when crack growth mode transitions are observed and when strong history dependence of crack growth behavior occurs. 

Cell lines have been used extensively to study the cytotoxicity of substances to fish cells12,184. Most studies have employed tests of general or basal cytotoxicity rather than tests of injury to differentiated cells and their functions. Basal cytotoxicity refers to impairment to cellular activities shared by all or most cells. Evaluating basal cytotoxicity can be done in a variety of ways, which will be referred to as cell viability assays. Usually these tests are performed on cultures after exposure to putative toxicants for 72 h or less and can be described as short-term or acute assays. As a result of this short exposure, toxicants that act by inducing a particular cellular process, such as the xenobiotic metabolism, or by causing cumulative damage might be missed. 

Repetitive damage to some structure, such as an epithelial cell which might repetitively secrete endogenous chemicals to serve as the actual stimulus for the common chemical sense (sensation might increase with cumulative damage and might continue after cessation of the stimuli because of low-level inflammation). 

The major risk factor for acute renal failure is an elevated lithium concentration, particularly in association with dehydration. Concomitant therapy with neuroleptic agents may contribute. Chronic nephrotoxicity may result from cumulative damage due to repeated episodes of acute renal injury. 

We have chosen to study polymer failure In a framework which assumes that failure is the result of a cumulative damage process. When the damage reaches a critical value, then failure occurs. If the rate of damage accumulation is a function of only the current stress and not of stress rate or of the current state of damage, the simplest form of this concept is valid. 

The differences in chemiluminescence intensities of the samples at 25°C are discernible at a much earlier point than the differences in impact strengths. This observation is reasonable, since the former technique measures a dynamic process at the molecular level, while the latter responds to the cumulative damage to the sample up to the time of testing. The data are not completely in accord with this generalization, since the light... 

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