Introduction of a New Parameter to Quantify the Fatigue Damage in Asphalt Mastics and Asphalt Binder

This study involves the quantification of fatigue damage in asphalt materials by introducing a new fatigue damage parameter denoted as the F parameter. One waste filler, i.e., red mud and an asphalt binder were chosen to blend the asphalt mastics at three filler contents of 10, 20, and 30% respectively with respect to the volume of binder and tested at temperatures of 5, 15, and 25 °C. The proposed parameter incorporates the effect of both peak shear stress as well as the failure strain, and hence, can better represent the fatigue damage. A lower value of F is recommended for a better fatigue resistant material. The F parameter was found increasing with the increment in filler content, which signifies higher degree of damage with a high level of stiffening. On the other hand, it consistently decreased with the increment in temperature. The behavior of the materials under the action of increasing shear strain was clearly justified by using the F parameter corresponding to different filler contents and the testing temperatures. In addition to that, the observations from the F parameter were also complemented by the fatigue diagrams. Hence, the proposed parameter is envisaged to be a promising fatigue damage indicator in future works.

Fatigue Life Prediction of Half-Shaft Using the Strain-Life Method

Fatigue life prediction is an important part of the reliability and durability analysis of automobile components. Based on Wang and Brown’s framework, multiaxial random fatigue damage was adopted to predict the fatigue life of half-shaft. The stress analysis of half-shaft was resolved analytically to determine the local stress tensor in the potential area of fracture. The maximum shear strain fatigue damage parameter and the normal stress fatigue damage parameter were evaluated to predict the fatigue life of half-shaft. The results show that the prediction method is reliable and meets the service life and safety requirements.

The influence of a quay crane sea transportation on its further exploitation

For the last decades, fully erected container cranes have been delivered to a customer site by ships. On one hand, using this method of transportation is very attractive due to its cost and time savings. However, on the other hand, being exposed to cycling loads from the ship motions during the sea voyage, the crane structure accumulates fatigue damage. Using the accumulated fatigue damage parameter, the crane transportation could be associated with the amount of the working cycles the crane could have worked out during its normal operating at the customer site. In the presenting paper the research for the real case of a new crane voyage from China to Ukraine has been done.

Characterization of Biaxial Fatigue by Using Strain Energy Density Approach for Steel

This research discussed on the determination of the appropriate fatigue damage parameter to predict the fatigue life when material subjected to the biaxial loading condition with the consideration of the energy dissipated. Servo-hydraulic machine is used for the constant amplitude cyclic testing on smooth solid mild steel. The results showed that in the low cycle fatigue, the total strain energy density can represent the accumulative of fatigue damage and characterize on the damage parameters. The relationship has been proposed which the data satisfactorily correlated for the R2 is 0.8656. In addition, the hysteresis loop represent the area under the graph was the energy stored in the material during the loading and unloading condition. Hence the circumstances showed the deformation process governing the nucleation and propagation of fatigue cracks associated with the energy dissipated.

Fatigue Behaviour of Lead-Free Solder Interconnections in Life Prediction of Trilayer Structures Subjected to Thermal Cycling

Trilayer structures such as flip chip plastic ball grid array (FC-PBGA) packages are bodies made of a large variety of dissimilar materials. Due to the coefficients of thermal expansion (CTE) mismatches between and temperature gradients within the layers, thermally induced interaction becomes a typical type of the loads for the joint layer made of lead-free solder joint interconnections. Thermal stresses and strains at the interfaces of solder joints and neighboring adhesive layers are the cause for solder joint fatigue failures, which account for the most common package failures. The current study puts forward a fatigue life prediction method for a trilayer structure using the critical plane-energy fatigue damage parameter in combination with the modified Coffin-Manson life model. The proposed method of calculated fatigue damage parameter for the samples of study, along with their experimental life (Nf50%) under two different thermal conditions is presented. The values of life in (0–100°C) condition and (25–125°C) with the same temperature ramp rate and dwell conditions are found to differ by a factor of 1.3 where the structures tested under (0–100°C) condition show lower lives. The present study further correlated the fatigue damage parameters with the Coffin-Manson type equation to calculate/predict the fatigue life of structures under (25–125°C) condition. The results of the Nf50 fatigue life prediction versus the experimental cycles show that the predicted lives of samples with SAC305 solder joints fall apart with a factor ranging from (1.24)∼(−1.45). The advantage of the proposed method in comparison with the existing methods in life prediction of the trilayer structure with solder alloy is that there are no empirical parameters involved in energy-critical plane damage parameter in life prediction of the trilayer structure. Parameters within the proposed approach purely involves mechanical and fatigue properties of the midlayer alloy.

Fatigue Damage of Al/SiC Composites - Macroscopic and Microscopic Analysis

The results of comparative examinations of mechanical behaviour during fatigue loads and microstructure assessment before and after fatigue tests were presented. Composites of aluminium matrix and SiC reinforcement manufactured using the KoBo method were investigated. The combinations of two kinds of fatigue damage mechanisms were observed. The first one governed by cyclic plasticity and related to inelastic strain amplitude changes and the second one expressed in a form of ratcheting based on changes in mean inelastic strain. The higher SiC content the less influence of the fatigue damage mechanisms on material behaviour was observed. Attempts have been made to evaluate an appropriate fatigue damage parameter. However, it still needs further improvements.