An Experimental Investigation of the Effects of Cycling Frequency and Temperature on the Fatigue Life of 60 Tin/40 Lead Solder

1996 ◽  
Vol 118 (4) ◽  
pp. 280-284 ◽  
Author(s):  
Gregory D. Leece ◽  
Ibrahim Miskioglu ◽  
David A. Nelson
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Load Control ◽  
Model Parameters ◽  
Strong Correlations ◽  
Mechanical Fatigue ◽  
Fatigue Model ◽  
Cycling Frequency ◽  
Effects Of Temperature ◽  
Cycles To Failure

The effects of cycling frequency and temperature on the fatigue life of solder has been analyzed. Mechanical fatigue life experiments were conducted under load control while varying the temperature and cycling frequency. Using the experimental data, a fatigue model was formulated based on the Basquin and the Coffin-Manson relations, introducing the effects of temperature and frequency. The model parameters were obtained by a statistical method incorporating multiple linear regression. Using the model, estimated values of cycles to failure at each of the testing temperatures and frequency were calculated. Using the estimated values, an evaluation of each of the models was conducted, resulting in strong correlations between the model’s estimation and the experimental data.

scholarly journals Growth Limits of Listeria monocytogenesas a Function of Temperature, pH, NaCl, and Lactic Acid

2000 ◽  
Vol 66 (11) ◽  
pp. 4979-4987 ◽  
Author(s):  
S. Tienungoon ◽  
D. A. Ratkowsky ◽  
T. A. McMeekin ◽  
T. Ross
Keyword(s):  
Experimental Data ◽  
Logistic Regression ◽  
Lactic Acid ◽  
Model Parameters ◽  
Food Borne ◽  
Food Borne Illness ◽  
Effects Of Temperature ◽  
Growth Limits ◽  
Food Safety Risk ◽  
Temperature Water

ABSTRACT Models describing the limits of growth of pathogens under multiple constraints will aid management of the safety of foods which are sporadically contaminated with pathogens and for which subsequent growth of the pathogen would significantly increase the risk of food-borne illness. We modeled the effects of temperature, water activity, pH, and lactic acid levels on the growth of two strains ofListeria monocytogenes in tryptone soya yeast extract broth. The results could be divided unambiguously into “growth is possible” or “growth is not possible” classes. We observed minor differences in growth characteristics of the two L. monocytogenes strains. The data follow a binomial probability distribution and may be modeled using logistic regression. The model used is derived from a growth rate model in a manner similar to that described in a previously published work (K. A. Presser, T. Ross, and D. A. Ratkowsky, Appl. Environ. Microbiol. 64:1773–1779, 1998). We used “nonlinear logistic regression” to estimate the model parameters and developed a relatively simple model that describes our experimental data well. The fitted equations also described well the growth limits of all strains of L. monocytogenesreported in the literature, except at temperatures beyond the limits of the experimental data used to develop the model (3 to 35°C). The models developed will improve the rigor of microbial food safety risk assessment and provide quantitative data in a concise form for the development of safer food products and processes.

Rapid Characterization of Fatigue Performance With Application to Additive Manufactured Components

2020 ◽  
Author(s):  
Dino A. Celli ◽  
M.-H. Herman Shen ◽  
Onome E. Scott-Emuakpor ◽  
Tommy J. George
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Life Prediction ◽  
Prediction Method ◽  
Experimental Tests ◽  
Parameter Selection ◽  
Process Parameter ◽  
Fatigue Life Prediction ◽  
Fatigue Performance ◽  
Cycles To Failure

Abstract The aim of this paper is to provide a fatigue life prediction method which can concurrently approximate both SN behavior as well as the inherent variability of fatigue efficiently with a limited number of experimental tests. The purpose of such a tool is for the quality assessment and verification of components using Additive Manufacturing (AM) processes and other materials with a limited knowledgebase. Interest in AM technology is continually growing in many industries, such as aerospace, automotive, or biomedical. But components often result in highly variable fatigue performance. The determination of optimal process parameters for the build process can be an extensive and costly endeavor due to either a limited knowledgebase or proprietary restrictions. Quantifying the significant variability of fatigue performance in AM components is a challenging task as there are many causes including machine to machine differences, recycles of powder, and process parameter selection. Therefore, a life prediction method which can rapidly determine the fatigue performance of a material with little or no prior information of the material and a limited number of experimental tests is developed as an aid in process parameter selection and fatigue performance qualification. This is performed by using a previously developed and simplistic energy based fatigue life prediction method, or Two Point method, to predict the inherent variability associated with fatigue performance. The proposed approach is verified by using predicted distributions of stress and cycles to failure and comparing with experimental data at 104 and 106 cycles to failure. SN life prediction is modeled via a modified Random Fatigue Limit (RFL) model where the two RFL model parameters are evaluated using Bayesian statistical inference and stochastic sampling techniques for distribution estimation. This is performed in a dynamic way such that the life prediction model is continually updated with the generation of experimental data.

New parameters controlling the effect of temperature on enzyme activity

2007 ◽  
Vol 35 (6) ◽  
pp. 1543-1546 ◽  
Author(s):  
R.M. Daniel ◽  
M.J. Danson ◽  
R. Eisenthal ◽  
C.K. Lee ◽  
M.E. Peterson
Keyword(s):  
Experimental Data ◽  
Enzyme Activity ◽  
Thermal Behaviour ◽  
Equilibrium Model ◽  
Thermal Inactivation ◽  
Effect Of Temperature ◽  
Model Parameters ◽  
Effects Of Temperature ◽  
Activity Loss

Arising from careful measurements of the thermal behaviour of enzymes, a new model, the Equilibrium Model, has been developed to explain more fully the effects of temperature on enzymes. The model describes the effect of temperature on enzyme activity in terms of a rapidly reversible active–inactive (but not denatured) transition, revealing an additional and reversible mechanism for enzyme activity loss in addition to irreversible thermal inactivation at high temperatures. Two new thermal parameters, Teq and ΔHeq, describe the active–inactive transition, and enable a complete description of the effect of temperature on enzyme activity. We describe here the Model and its fit to experimental data, methods for the determination of the Equilibrium Model parameters, and the implications of the Model for the environmental adaptation and evolution of enzymes, and for biotechnology.

A consolidation model for a creeping clay

1999 ◽  
Vol 36 (4) ◽  
pp. 754-759 ◽  
Author(s):  
DFE Stolle ◽  
P A Vermeer ◽  
P G Bonnier
Keyword(s):  
Experimental Data ◽  
Weak Form ◽  
Model Parameters ◽  
One Dimensional ◽  
Secondary Compression ◽  
Compression Creep ◽  
Consolidation Model ◽  
Finite Element Procedure ◽  
Effects Of Temperature ◽  
Leda Clay

A nonlinear theory of consolidation is presented which takes into account secondary compression. The theory is incorporated into a weak form of equilibrium that is suitable for a finite element procedure. The model is used to interpret Crawford's experimental data on Leda clay. Limitations of the model are discussed, and a few thoughts on the effects of temperature on the evaluation of model parameters are briefly presented.Key words: secondary compression, creep, one-dimensional consolidation, modelling.

scholarly journals A new type of S-N equation and its application to multiaxial fatigue life prediction

2021 ◽  
Author(s):  
xiangqiao yan
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Life Prediction ◽  
Multiaxial Fatigue ◽  
Fatigue Life Prediction ◽  
Metallic Materials ◽  
Material Constants ◽  
Numerical Fitting ◽  
Fatigue Model ◽  
New Type

The S-N equation is one of the most important equations in fatigue model investigation. A majority of fatigue models, including multiaxial fatigue model and mean effect models, are established on the basis of the S-N equation. Obviously, an accuracy of the S-N equation is very important. Taking into account that the S-N equation is, in fact, an empirical one in which the material constants are determined by numerical fitting fatigue experimental data, in this paper, the S-N equation can be improved, by further processing these fatigue experimental data, to present a new type of S-N equation that is more accurate than the S-N equation. The new type of S-N equation is called a similar S-N equation in this paper. By using a large number of experimental data of metallic materials reported in literature, an accuracy of the similar S-N equation has been proven.

scholarly journals Algorithm for determination of S-N curves of the structural elements subjected to cyclic loading

2018 ◽  
Vol 16 (1) ◽  
pp. 81-91 ◽  
Author(s):  
Nenad Stojkovic ◽  
Dragoslav Stojic ◽  
Srdjan Zivkovic ◽  
Gordana Toplicic-Curcic
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Cyclic Loading ◽  
Fatigue Tests ◽  
Likelihood Method ◽  
Model Parameters ◽  
Structural Elements ◽  
Number Of Cycles ◽  
Predetermined Number

Fatigue life prediction of structural elements subjected to cyclic loading is usually performed using S-N curves, obtained from the experimental data from fatigue tests. However, in some cases the samples do not exhibit failure, due to reaching the predetermined number of cycles, failure of a non-relevant segment or terminating the test because of some other reason. These samples are usually referred to as runouts, and the data obtained from them could be used for determination of S-N curves as well. In this paper, the algorithm based on Maximum Likelihood method is proposed for the determination of S-N curves from experimental data that contain runouts. Following the algorithm, a MATLAB code was written and the verification was performed using the experimental data from the literature. The results showed that it could be successfully used for taking into account the runouts in the process of determination of S-N model parameters. It was concluded that the inclusion of runouts could significantly influence the predicted fatigue life, especially at the lower stress levels.

Parameter Determination for Chloride and Tritium Transport in Undisturbed Lysimeters during Steady Flow

1992 ◽  
Vol 23 (2) ◽  
pp. 89-104 ◽  
Author(s):  
Ole H. Jacobsen ◽  
Feike J. Leij ◽  
Martinus Th. van Genuchten
Keyword(s):  
Experimental Data ◽  
Unsaturated Flow ◽  
Transport Model ◽  
Time Moment ◽  
Breakthrough Curves ◽  
Coarse Sand ◽  
Retardation Factor ◽  
Parameter Determination ◽  
Model Parameters ◽  
Water Fraction

Breakthrough curves of Cl and 3H2O were obtained during steady unsaturated flow in five lysimeters containing an undisturbed coarse sand (Orthic Haplohumod). The experimental data were analyzed in terms of the classical two-parameter convection-dispersion equation and a four-parameter two-region type physical nonequilibrium solute transport model. Model parameters were obtained by both curve fitting and time moment analysis. The four-parameter model provided a much better fit to the data for three soil columns, but performed only slightly better for the two remaining columns. The retardation factor for Cl was about 10 % less than for 3H2O, indicating some anion exclusion. For the four-parameter model the average immobile water fraction was 0.14 and the Peclet numbers of the mobile region varied between 50 and 200. Time moments analysis proved to be a useful tool for quantifying the break through curve (BTC) although the moments were found to be sensitive to experimental scattering in the measured data at larger times. Also, fitted parameters described the experimental data better than moment generated parameter values.

Fatigue Life of the Human Teeth: A Continuum Damage Approach

2019 ◽  
Vol 43 ◽  
pp. 1-19
Author(s):  
Theddeus Tochukwu Akano
Keyword(s):  
Fatigue Life ◽  
Damage Mechanics ◽  
Stress Amplitude ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Elastoplastic Model ◽  
Human Teeth ◽  
Proposed Model ◽  
Number Of Cycles ◽  
Cycles To Failure

Normal oral food ingestion processes such as mastication would not have been possible without the teeth. The human teeth are subjected to many cyclic loadings per day. This, in turn, exerts forces on the teeth just like an engineering material undergoing the same cyclic loading. Over a period, there will be the creation of microcracks on the teeth that might not be visible ab initio. The constant formation of these microcracks weakens the teeth structure and foundation that result in its fracture. Therefore, the need to predict the fatigue life for human teeth is essential. In this paper, a continuum damage mechanics (CDM) based model is employed to evaluate the fatigue life of the human teeth. The material characteristic of the teeth is captured within the framework of the elastoplastic model. By applying the damage evolution equivalence, a mathematical formula is developed that describes the fatigue life in terms of the stress amplitude. Existing experimental data served as a guide as to the completeness of the proposed model. Results as a function of age and tubule orientation are presented. The outcomes produced by the current study have substantial agreement with the experimental results when plotted on the same axes. There is a notable difference in the number of cycles to failure as the tubule orientation increases. It is also revealed that the developed model could forecast for any tubule orientation and be adopted for both young and old teeth.

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