scholarly journals Laser Joining of Continuous Glass Fiber Composite Pre-Forms

2012 ◽  
Author(s):  
Huade Tan ◽  
Y. Lawrence Yao
Keyword(s):  
Joint Strength ◽  
Axial Direction ◽  
Fiber Bundles ◽  
Laser Fusion ◽  
Single Bundle ◽  
Filler Materials ◽  
Thickness Direction ◽  
Laser Joining ◽  
Joint Morphology ◽  
Joining Process

A laser fusion joining method is investigated for the purpose of through thickness strengthening of fiber pre-forms used in the vacuum infusion fabrication of thick composite structures. Laser joining is achieved without filler materials to replace adhesives, pins or stitches used in conventional composite fabrication. A two step joining process is developed to fuse fibers within a single bundle and between multiple fiber bundles. Finite element analysis is used to investigate the joint strength with respect to joint morphology. Joint strength is found to be a function of the fiber contact angle and packing density at the joint interface. Tensile tests show that laser joined fiber bundles exhibit higher strength than comparable fastening methods. Lessons learned from the axial joining of fiber bundles are applied to joining in the radial and thickness directions of 3d pre-form architectures. Flow induced joint morphology and densification effects observed in the axial direction indicate the need for a two step joining process in the thickness direction. Fiber compaction effects on joint strength in the axial direction motivate the need for high fiber packing fraction at joint interfaces in the thickness direction.

scholarly journals Porosity Elimination in Modified Direct Laser Joining of Ti6Al4V and Thermoplastics Composites

2019 ◽  
Vol 9 (3) ◽  
pp. 411 ◽  
Author(s):  
Haipeng Wang ◽  
Yang Chen ◽  
Zaoyang Guo ◽  
Yingchun Guan
Keyword(s):  
Glass Fiber ◽  
Fracture Strength ◽  
Joint Strength ◽  
Surface Texturing ◽  
Practical Applications ◽  
Laser Joining ◽  
Glass Fiber Reinforced ◽  
Hybrid Joints ◽  
Direct Laser ◽  
Joining Process

Hybrid lightweight components with strong and reliable bonding qualities are necessary for practical applications including in the automotive and aerospace industries. The direct laser joining method has been used to produce hybrid joints of Ti6Al4V and glass fiber reinforced polyamide (PA66-GF30). Prior to the laser joining process, a surface texturing treatment is carried out on Ti6Al4V to improve joint strength through the formation of interlock structures between Ti6Al4V and PA66-GF30. In order to reduce the generated micro-pores in Ti6Al4V-PA66-GF30 joints, a modified laser joining method has been proposed. Results show that only very few small micro-pores are generated in the joints produced by the modified laser joining method, and the fracture strength of the joints is significantly increased from 13.8 MPa to 41.5 MPa due to the elimination of micro-pores in the joints.

scholarly journals Laser Joining of Continuous Glass Fiber Composite Preforms

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
Huade Tan ◽  
Y. Lawrence Yao
Keyword(s):  
Glass Fiber ◽  
Laminate Composite ◽  
Fiber Composite ◽  
Fiber Bundles ◽  
Laser Fusion ◽  
Joint Interface ◽  
Single Bundle ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Composite Fabrication

A laser fusion joining method is investigated for the purpose of through thickness strengthening of glass fiber reinforced laminate composites. Laser fusion joining is evaluated as a potential process to replace mechanical reinforcements used in conventional laminate composite fabrication. A two step laser process is developed to form fusion bonds between fibers within a single bundle and between adjacent fiber bundles. Coupled heat transfer and viscous flow modeling is carried out to investigate the temperature and dynamics of the joining process under three experimentally observed conditions. Linear elastic finite element analysis is used to investigate the effect of joint morphology on stress concentrations and strength. Joint strength is found to be a function of the fiber contact angle and packing density at the joint interface. Tensile tests show that laser joined fiber bundle strength is on the same order of magnitude as the raw fiber bundles. The challenges to laser processing of three dimensional fiber reinforcements in laminate composite fabrication are discussed.

Process Characteristics of Laser Brazing Aluminium Alloys

2005 ◽  
Vol 6-8 ◽  
pp. 135-142 ◽  
Author(s):  
Fritz Klocke ◽  
A. Castell-Codesal ◽  
D. Donst
Keyword(s):  
Aluminium Alloys ◽  
Smooth Surface ◽  
Joint Strength ◽  
Processing Time ◽  
Laser Brazing ◽  
Working Temperature ◽  
Process Characteristics ◽  
Laser Joining ◽  
Brazed Joints ◽  
Joining Process

Compared to welding, laser brazing offers a suitable possibility to lower the working temperature and to join unweldable material combinations, while maintaining the numerous advantages of the laser joining process. Beside an acceptable joint strength, the brazed joints are characterised by a smooth surface and seams with almost no pores. As a result of this laser brazing combines the advantages of conventional brazing and laser welding. Within the scope of this paper the laser brazing process and its characteristics are explained in detail. In particular the interrelation of temperature progress, available processing time for brazing/diffusion and the thickness of the diffusion layer is discussed. Subsequently the material specific particularities of laser brazing aluminium alloys are described and discussed with respect to recently gained results.

Assessment of mechanical and biocompatible performance of ultra-large nitinol endovascular devices fabricated via a low-energy laser joining process

2021 ◽  
pp. 088532822110195
Author(s):  
Moataz Elsisy ◽  
Mahdis Shayan ◽  
Yanfei Chen ◽  
Bryan W Tillman ◽  
Catherine Go ◽  
...  
Keyword(s):  
Laser Power ◽  
In Vitro Study ◽  
Spot Size ◽  
Laser Joining ◽  
Study Results ◽  
Energy Laser ◽  
Joining Process ◽  
Endovascular Devices ◽  
Low Energy Laser

Nitinol is an excellent candidate material for developing various self-expanding endovascular devices due to its unique properties such as superelasticity, biocompatibility and shape memory effect. A low-energy laser joining technique suggests a high potential to create various large diameter Nitinol endovascular devices that contain complex geometries. The primary purpose of the study is to investigate the effects of laser joining process parameters with regard to the mechanical and biocompatible performance of Nitinol stents. Both the chemical composition and the microstructure of the laser-welded joints were evaluated using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). In vitro study results on cytotoxicity demonstrated that the joining condition of 8 Hz frequency and 1 kW laser power showed the highest degree of endothelial cell viability after thermal annealing in 500°C for 30 min. Also, in vitro study results showed the highest oxygen content at 0.9 kW laser power, 8 Hz frequency, and 0.3 mm spot size after the thermal annealing. Mechanical performance test results showed that the optimal condition for the highest disconnecting force was found at 1 Hz frequency and 1 kW power with 0.6 mm spot size. Two new endovascular devices have been fabricated using the optimized laser joining parameters, which have demonstrated successful device delivery and retrieval, as well as acute biocompatibility.

scholarly journals A Comparative Study of Ductile Damage Models Approaches for Joint Strength Prediction in Hot Shear Joining Process

2017 ◽  
Vol 207 ◽  
pp. 1689-1694 ◽  
Author(s):  
Mohanraj Murugesan ◽  
Seonggi Lee ◽  
Dongwook Kim ◽  
Youn-Hee Kang ◽  
Naksoo Kim
Keyword(s):  
Comparative Study ◽  
Joint Strength ◽  
Ductile Damage ◽  
Strength Prediction ◽  
Damage Models ◽  
Joining Process

Investigation on Thermal Energy Storage Characteristics of Thermocline Tank with Mixture Filler Materials

2014 ◽  
Vol 687-691 ◽  
pp. 3512-3515
Author(s):  
Jing Xiao Han ◽  
Yong Ping Yang ◽  
Jia Rui Wu ◽  
Hong Juan Hou
Keyword(s):  
Temperature Gradient ◽  
Axial Direction ◽  
Heat Transfer Fluid ◽  
Inlet Temperature ◽  
Filler Materials ◽  
Indirect Contact ◽  
Lower Velocity ◽  
Air Inlet ◽  
Sand Filler ◽  
Storage Characteristics

An experimental setup for indirect contact sensible heat TES was built. Air was chosen as the heat transfer fluid to flow inside the tubes and carry heat, while the mixture in the tank contacts the outside of the tubes. The results were also compared with pure sand filler material. It can be found that and the TES efficiency of mixture increased by 18% compared with pure sand, what’s more, its temperature gradient along the radical direction was also lower, while its temperature gradient along the axial direction was higher, so the mixture was better. Under various air inlet temperature (60-70°C), TES performances were similar, but for real power generation, further work on optimism temperature range was needed. Air velocity was also important to TES tank, lower velocity can not only increase the TES efficiency, but also enlarge the thermocline temperature gradient.

Local Effects of Welding Seams with Laser-Based Joining Concepts for High-Strength Load-Transferring Structure Modules

2007 ◽  
Vol 22 ◽  
pp. 49-55
Author(s):  
Mitja Schimek ◽  
O. Meier ◽  
A. Ostendorf ◽  
L. Engelbrecht ◽  
H. Haferkamp
Keyword(s):  
High Strength ◽  
Strength Properties ◽  
Strength Increase ◽  
Local Effects ◽  
Final Assembly ◽  
Laser Joining ◽  
Local Material ◽  
Local Strength ◽  
Geometrical Effects ◽  
Joining Process

In subproject B1, local physical and geometrical effects which have only been observed so far as side effects in the laser joining process, are to be used purposefully, in order to achieve graded strength properties and to improve the component rigidity significantly. One aim of the work in the first requested period is the investigation of effects of laser-based joining connections on the structure rigidity for simplified sample geometries. A defined local strength increase will first be done on blind seams and later on seams with suitable seam geometries. In the context of SFB 675, laser joining processes are to be developed further so that the final assembly can take place with and other methods to increase strength for semi-finished products without considerably changing the local material characteristics. Beyond that, general rigidity effects of the connections are to be used purposefully for rigidity improvement.

Numerical Investigation of Knurled Shaft-Hub Connections and Especially of the Joining Process

2013 ◽  
Vol 773-774 ◽  
pp. 18-27 ◽  
Author(s):  
Stefan Kleditzsch ◽  
Michael Lätzer ◽  
Birgit Awiszus ◽  
Erhard Leidich
Keyword(s):  
Axial Direction ◽  
Material Structure ◽  
Natural Material ◽  
The Finite Element Method ◽  
Interference Fit ◽  
Local Loads ◽  
Parameter Variations ◽  
Cylindrical Bore ◽  
Joining Process

Faced with increasing cost pressures, manufacturers need to find new solutions for shaft-hub connections. One example is the knurled interference fit, where a shaft with knurls and interference is pressed in a soft hub with a cylindrical bore. At present the potential of the knurled interference fit is not fully used, because there are no general standards available for the design and for the joining process. But the joining process in particular has an important impact on the join strength. A predominantly forming joining process offers some advantages compared to cutting. Forming allows a clearly higher contact pressure over the groove because of the displacement of the hub material, which leads to greater axial reliability. Also, the natural material structure is preserved by the forming, and this, in combination with the hardening of the hub, should allow a higher transmittable torque. The Finite Element Method is used for detailed investigation of the joining process and the transmission behavior in the axial direction. With this method, the local loads, for example the hardening of the hub over the groove due to the formed join, are investigated as well as further parameter variations (e.g., chamfer angle, interference). Hence, an analytical approach for the determination of the necessary joining force was derived.

Modeling and Optimization of Mask Assisted Laser Transmission Micro Joining Process

2014 ◽  
Vol 620 ◽  
pp. 10-16
Author(s):  
Zhen Guan Zhao ◽  
Hui Xia Liu ◽  
Ye Cai ◽  
Yan Wei Wu ◽  
Xiao Wang
Keyword(s):  
Mathematical Model ◽  
Response Surface Methodology ◽  
Experimental Design ◽  
Process Parameters ◽  
Joint Strength ◽  
Slit Width ◽  
Joint Width ◽  
The Mathematical Model ◽  
The Relationship ◽  
Joining Process

This article uses semiconductor laser for mask assisted laser transmission micro joining PET and PET with clear weld absorbents, the mask slit width is 0.3mm, using CCD to plan experimental design. The mathematical model of joining process parameters with joint strength and joint width was established using response surface methodology. Experimental verification was also done. The actual joint width was compared to mask slit width and the process parameters were optimized. The results show that the mathematical model can response the relationship between process parameters and joining quality, the mask can effectively control the joint width, reasonable process parameters can obtain high-precision, high-intensity joining quality.

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