Vibration Fracture Research Articles

A review: effect of copper percentage solder alloy after laser soldering

PurposeThis study aims to review the effect of copper percentage in Sn-based solder alloys (Sn-xCu,x= 0–5 Wt.%) on intermetallic compound (IMC) formation and growth after laser soldering.Design/methodology/approachThis study reviews the interfacial reactions at the solder joint interface, solder joint morphology and the theory on characterizing the formation and growth of IMCs. In addition, the effects of alloying and strengthening mechanism, including wettability, melting and mechanical properties are discussed.FindingsThis paper presents a comprehensive overview of the composition of tin-copper (Sn-Cu) solders with a potential to enhance their microstructure, mechanical characteristics and wettability by varying the Cu percentage. The study found that the best Cu content in the Sn-xCu solder alloy was 0.6–0.7 Wt.%; this composition provided high shear strength, vibration fracture life value and ideal IMC thickness. A method of solder alloy preparation was also found through powder metallurgy and laser soldering to improve the solder joint reliability.Research limitations/implicationsThis study focuses on interfacial reactions at the solder joint interface, solder joint morphology, modelling simulation of joint strength and the theory on characterising the formation and growth of IMC.Originality/valueThe paper comprehensively summarises the useful findings of the Sn-Cu series. This information will be important for future trends in laser soldering on solder joint formation.

Design of a Hydraulic Pump of Tractor for Manufacturing with 3D printer Technology

In this work, a couple of spur gears design was changed by two double- helical gears design with maintaining other parts in the same size approximately for a hydraulic pump of agricultural tractor. The main purpose of this attempt was to obtain a new hydraulic pump with better specifications and performance. The new elements of the pump were designed using 3D Solid Works software then the stresses analyses and CFD analyses were archived using ANSYS software. The results showed a better flow rate of the hydraulic fluid by about 17%. This reflects the success of this idea where the flow rate of the new design was much higher compared with spur gear pump. This will conclude that the new design led to improve the pump performance. Moreover, the new pump overcomes the problems that usually appear in spur gears such as noise, vibration fracture. However, this design considers one of the most difficult parts in manufacture process therefor, it was recommended to fabricate it with3D printers

Gradient microstructure and vibration fatigue properties of 2024-T351 aluminium alloy treated by laser shock peening

To investigate the improvement in vibration fatigue and the strengthening mechanism of laser shock peening, a nanosecond laser was used to strengthen the 2024-T351 aluminium alloy. Accordingly, the microstructure, residual stress, nanohardness and surface roughness of the treated alloy were measured. Subsequently, the vibration fatigue damage and fatigue life were evaluated, and the vibration fracture morphology was observed. The results showed that the grains in the peened surface were refined. A residual stress of −141 MPa and a nanohardness of 3.1 GPa were obtained by laser shock peening. Based on the relationship between the peened microstructure and fracture morphology, it was deduced that an increase in the grain boundaries led to a lower crack initiation rate and a higher crack initiation life. The compressive residual stress decreased the crack growth rate and increased the crack growth life. Therefore, laser shock peening increases the total vibration fatigue life by about 63.5%.

Vibration Fracture Mechanism and Optimization Design of Array Power Supply for Near-Space SAR

The random vibration failure of an array power supply for near-space SAR was analyzed. The fracture mechanism and the fracture reason of fracture formation in the specimen were investigated. The results show that antishock MOS pin breaks first, and the power supply is still in the working state during the process of random vibration. This caused dischargings at the tip of the fracture and melting of the tip of the broken pin which form a river-shaped fracture and granular tissue. The plastic fracture with typical dimple morphology of the pins for the resistor tube occurred during the random vibration. The intergranular fracture appeared at the welding part of the electronic components for array power supply, which presented a brittle fracture mechanism. The fracture was dominated by a ductile fracture for components when the stress produced by the vibration was close to the yield strength of the material. The fracture was dominated by a brittle fracture for components when the stress produced by the vibration was far beyond the yield strength of the material. A simulation evaluation system based on the high-confidence model was proposed. The stress of the electronic components for array power supply and its welding was much lower than the allowable strength of the material by the optimization of the structure and the form of the welding for the array power supply. The sample was successfully tested and verified without any further fracture problems.

Vibration Fracture Analysis and Optimization Design of Ocean Ship Transmission Shaft

ABSTRACT Yu, Z.; Jia, H., and Huang, X., 2018. Vibration fracture analysis and optimization design of ocean ship transmission shaft. In: Liu, Z.L. and Mi, C. (eds.), Advances in Sustainable Port and Ocean Engineering. Journal of Coastal Research, Special Issue No. 83, pp. 179–183. Coconut Creek (Florida), ISSN 0749-0208. Aiming at solving the fracture problem of a ocean ship transmission shaft. Firstly, the ocean ship transmission shaft was constrained modal analysis by adopting finite elements method, the analysis results show that the first natural frequency was close to its excitation frequency, so the ocean ship transmission shaft resonance would be caused. Secondly, the ocean ship transmission shaft was modal test by adopting hammering method, the test results show that modal test frequency was basically consistent with the modal simulation frequency. Thirdly, the diameter and thickness of ocean ship transmission shaft tube were optimized and analyzed by adopting OptiStruct software, the optimal valu...

Vibration buckling and fracture analysis of a cracked cylindrical shell

Shell structures are susceptible to various types of imperfections and damage such as cracking, corrosion, chemical attack and time-dependent material degradation, which may impair their structural integrity and affect their service life. The effects of cracks are important considerations in the design of cylindrical shell structures as they influence on load carrying capacity and safety. This present work is a finite element investigation on the vibration, buckling and fracture analysis of a cracked cylindrical shell subjected to a time varying rotating speed. The effects of crack length, orientation of crack and length-diameter ratio of the cylindrical shell are investigated under free-vibration and buckling. The fracture parameters like stress intensity factor and J-integral of the cracked shell are also studied considering the influence of crack length and crack orientation. Results reveal that the crack length and crack orientation can affect the vibration, buckling behaviour of the cylindrical shell significantly.

Influence of Pre-Deformation of 5052H112 Alloy on Tensile Properties and Fracture Resistance under Vibration

This study prepared a 5052H112 alloy under different cold-rolled reductions to explore its microstructure and mechanical properties. The experimental results indicated that the cold-rolled specimens had good tensile properties and better vibration fracture resistance, due to the high densities of dislocation and small aspect ratio of crystal grain. The stress-elongation curves of all specimens showed the serrated yielding. The high densities of dislocation and small aspect ratio of crystal grain introduced by cold-rolling could hold the mobile dislocations long enough to let Mg atoms form atmospheres around them. In addition, the crack propagation behavior of all specimens showed that slip bands can be observed in the vicinity of the main crack and be suppressed by increasing the cold-rolled reduction. Crack propagation showed that rolled specimens exhibit decreasing crack propagation rates with increased matrix strengthening (cold-rolling). Therefore, it can be concluded that a large number of dislocation tangles introduced by cold-rolling are effective in improving mechanical properties. [doi:10.2320/matertrans.M2014305]

Effect of microstructural feature on the tensile properties and vibration fracture resistance of friction stirred 5083 Alloy

In this study, 5083 Al–Mg plates were friction stirred at optimal rotation speeds to investigate the tensile properties and vibration fracture resistance. As a result, grain refinement could be observed at the stir zone with 7 μm average grain size and fine particles could be observed as well. The tensile strain–elongation curves reveal that the tensile strength and elongation tended to increase as the microstructure was refined in the friction stirred sample. The D–N curves of the specimens recorded under an identical initial deflection show that there was a slight difference between the parent metal and the friction stirred sample. A refined grain size is partially responsible for an improvement in vibration fracture resistance; however there is another factor which plays a role too. It should be noted that the deterioration of vibration fracture resistance is a consequence of fine particles stirred into a softened matrix. From the crack propagation results, an intergranular crack propagation feature can be recognized in the friction stirred specimen, and it is reasonable to suggest that the fine particles played an important role in the deterioration of the vibration fracture resistance.

Mechanical Responses of Superlight β-Based Mg-Li-Al-Zn Wrought Alloys under Resonance

To extend the application of lightweight Mg alloys in the automotive industry, this study suggests a β-based Mg-Li alloy (LAZ1110) with superior vibration fracture resistance by means of material design. In the cold-rolled state, a strengthened β matrix by the additions of Al and Zn, as well as intergranular platelike α precipitates, which are able to stunt the crack growth, contributes to a comparable vibration life with commercial Mg-Al-Zn alloys under a similar strain condition.

Vibration fracture resistance of 5052H112 aluminum alloy processed by cold rolling and friction stirring

Abstract Hot-rolled Al–3Mg alloy processed by various cold-rolled reductions exhibited excellent vibration fracture resistance, however subsequent friction stirring did not endow better vibration fracture resistance than cold-rolled samples in spite of possessing microstructural refinement and homogenization. The D–N curve under a constant initial deflection amplitude (6.5 mm) also showed that the vibration fracture resistance of cold-rolled specimens increased as a result of the slower crack propagation rate. All samples used in this investigation showed a work hardening feature from the initial stage of the D–N curve, and the deflection amplitude tended to increase as the number of vibration cycles increased. During this ascending stage, slip band cracking and strain hardening in the vicinity of the main crack could be recognized. The D–N curve feature of the cold-rolled samples depicted a longer plateau region while the deflection amplitude was at its maximum. It is suggested that the dislocation tangles introduced by cold rolling can strengthen the matrix. As a result, the deflection amplitude drops could be associated with increasing the dislocation tangles due to prior cold rolling while the main crack achieved a critical crack length.

Mechanical Properties and Resonant Characteristics of Friction Stirred AZ31-Mg Alloy

An annealed AZ31-Mg specimen (AZ31-O) was given a FSP (friction stir process) to obtain a AZ31-FSP specimen, whose tensile and vibration fracture mechanisms are examined in this study. As a result of FSP, the structure of the stirred zone (SZ) separated into two zones: (1) the SZ-top had a finer structure and (2) the grain size of the SZ-bottom was like the AZ31-O specimen. Because the basal plane (0002) had pressed close to the trace surface of the onion structure in the SZ, the recrystallization of FSP increased the elongation of the specimens at room temperature, but the refined grains had no contribution to tensile strength and had an unusual Hall-Petch effect. Notably, the vibration deformed resistance of the AZ31-FSP specimen was higher than that of the AZ31-O specimen. The FSP specimen not only possessed finer structures but also had a preferred orientation in the stirred zone. This led to an increase in the crack tortuosity, which in turn increased the crack propagation resistance and the vibration life.

Vibration fracture behavior of Sn–9Zn–xCu lead-free solders

The effect of Cu content on the microstructure and the vibration deformation mechanisms of a potential lead-free solder, Sn–9Zn–xCu (x = 0.2, 0.5, 0.7, 1.0 wt.%), are examined in this study. Results show that Zn-rich phase and Sn–Zn eutectic decreased, while Cu–Zn intermetallic compound and proeutectic Sn-rich phase increased with increasing the Cu content. For the specimens with high Cu content (0.7Cu and 1.0Cu), hard massive Cu5Zn8 existed mostly amongst the proeutectic Sn-rich phase dendrites, and Zn-rich dispersed unevenly, leading to the deterioration in the tensile strength and ductility. Under a constant vibration force and constant initial-deflection testing, the high Cu specimen with a higher damping capacity was able to absorb more vibration energy and thus possessed a greater vibration fracture resistance. In addition, the lamellar-deformed structures (LDS) and Cu5Zn8 were able to increase the crack tortuosity, which in turn increased the crack propagation resistance.

Crystallization, morphology and distribution of Ag 3Sn in Sn–Ag–Cu alloys and their influence on the vibration fracture properties

Since Ag 3Sn phase plays a decided role in the performance of Sn–Ag–Cu solders, this study varied the solidification rate and Ag content to clarify the formation, morphology and distribution of Ag 3Sn in Sn–Ag–Cu alloys, as well as their influence on the tensile properties and vibration fracture resistance under different vibration conditions. Results show that a less packed distribution of Ag 3Sn in the eutectic regions and a larger area of β-Sn dendrites contributed to a higher damping capacity and thus a greater vibration life under constant force conditions. Acicular eutectic Ag 3Sn and large primary Ag 3Sn plates accelerated crack growth and thus degraded the ductility and vibration fracture resistance particularly when the damping effect was removed.

Resonant characteristics of the microelectronic Sn–Cu solder

The effect of Cu content on the microstructure and the vibration deformation mechanisms of a potential lead-free solder, Sn– xCu ( x = 0.3, 0.6, 1.3, 1.7 wt.%), are examined in this study. The results show that proeutectic Sn-rich phase finer, while Cu 6Sn 5 intermetallic compounds increased with increasing the Cu content. For the specimens with high Cu content (1.3Cu and 1.7Cu), hard massive Cu 6Sn 5 existed mostly amongst the proeutectic Sn-rich (β-Sn) phase dendrites and the fineness of Cu 6Sn 5 is advantageous to resonant life. Under both constant vibration force and a constant initial-deflection testing, the 0.3Cu specimen and 0.6Cu specimen with a higher damping capacity was able to absorb more vibration energy and thus possessed a greater vibration fracture resistance. In addition, the lamellar-deformed structures (LDS) of β-Sn and the finer Cu 6Sn 5 were able to increase the crack tortuosity, which in turn increased the crack propagation resistance.

Vibration behavior of light metals: Al–Zn alloy and Mg–Al–Zn alloy

Both Al–Zn alloy and Mg–Al–Zn alloy are considered as high damping and light materials. This study investigated the effects of the structure and the composition on the vibration fracture characteristics of the Al–xZn alloy and the Mg–xAl–Zn alloy under resonance. For Al–xZn (x = 7, 11, 49, and 83 wt.%) alloys, under both constant force and initial-deflection conditions, the 7Zn specimen showed the greatest vibration life. For Mg–xAl–Zn (x = 3, 6, and 9 wt.%) alloys, experimental results indicate that the AZ31-F as-extruded samples showed a greater vibration life, while high Al fully annealed samples (AZ91-O) had greater vibration fracture resistance under constant force conditions.

Microstructural Characteristics and Vibration Fracture Properties of Al-Mg-Si Alloys with Excess Cu and Ni

This study investigated the effect of co-addition of Cu and Ni on the microstructure and vibration properties of Al-Mg-Si alloys. The results show that additions of Cu and Ni resulted in the formation of Al3(Ni,Cu) phase, a harder Al matrix and an accelerated aging rate. Nanoindentation analysis indicates that the Al3(Ni,Cu) phase exhibits a hardness of 7.7 GPa and Young’s modulus of 141.2 GPa. Due to the increased modulus by reinforcement effect of Al3(Ni,Cu), the alloyed samples possessed a higher resonant frequency. However, the damping capacity was reduced with alloying because of the hardened matrix. It was also found that since microcracks could be generated from the irregular-shaped Al3(Ni,Cu) in the vicinity of the tip of the main crack when suffering vibration deformation, the crack propagation resistance of the alloyed samples was inferior.

Deformation Fracture Characteristics of Microelectronic Sn-3.0Ag-0.5Cu-<I>x</I>Ni Solders

The effect of Ni content on the microstructure, as well as the tensile and vibration fracture mechanisms of a potential lead-free solder, Sn-3.0Ag-0.5Cu-xNi (0.02, 0.07, 0.1, 0.2 and 0.3 mass%), are examined in this study. The results show that both Sn-Ni-Cu and Sn-Cu-Ni-Ag intermetallic compounds (IMC) increased with increasing the Ni content. The IMCs mostly formed in the eutectic zones and a few in proeutectic Sn-rich phases. Notably, the Ni content of the bar-like Sn-Ni-Cu compounds was higher than that of the particle-like Sn-Cu-Ni-Ag compounds. In addition, the tensile deformed resistance of Sn-3.0Ag-0.5Cu-xNi solders decreased when the Ni content was increased. Adding Ni obtained finer structures, however the hard massive Sn-Ni-Cu in the eutectic zone deteriorated the tensile deformation resistance. For the lower Ni content specimens, the 0.07Ni specimen not only possessed finer structures but a large number of compounds which congregated were able to increase the crack tortuosity, which in turn increased the crack propagation resistance and the vibration life.

Vibration fracture properties of a lightweight Mg–Li–Zn alloy

This study investigated the performance of the Mg–9% Li–1% Zn magnesium alloy (LZ91) under resonance. Results show that LZ91 exhibited excellent damping capacity and thus a lengthy vibration life under constant push force conditions. However, on removal of the damping effect the LZ91 specimens showed an inferior vibration fracture resistance, probably due to its lower strength.

Microstructural characteristics and vibration fracture properties of Sn-Ag-Cu-TM (TM=Co, Ni, and Zn) alloys

This study investigated microstructure thermal behavior, and mechanical properties of Sn-3.3Ag-0.5Cu alloys (SAC) with the addition of transition metals (TM, Ni, Co, and Zn). Results show that alloying with TM elements was able to reduce the degree of undercooling and strengthen SAC alloys. Among these elements, only Zn can raise the ductility. CoSn and Cu-Ni-Sn intermetallics appeared, respectively, in the Co-containing and Ni-containing samples while coarse Sn dendrites and a large area of eutectic phases could be observed in the specimens with Zn. These microstructural changes led to an inferior vibration fracture resistance under resonant vibration with a constant pull force.

The Resonant Vibration Fracture Characteristics of Al-xZn Alloy and Mg-xAl-Zn Alloy

Both Al-Zn alloy and Mg-Al-Zn alloy have been considered as high damping and light materials. For practical use, this study investigated the effects of the structure and the composition on the vibration fracture characteristics of the Al-xZn alloy and the Mg-xAl-Zn alloy under resonance. For Al-xZn (x=7, 11, 49, 83wt%) alloys, under both constant force and initial-deflection conditions, the 7Zn showed the greatest vibration life. For Mg-xAl-Zn (x=3, 6, 9wt%) alloys, experimental results indicate that the AZ31-F as-extruded samples showed a greater vibration life, while high Al fully-annealed samples (AZ91-O) had greater vibration fracture resistance under constant force conditions.