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 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 Laser Dissimilar Joining of Al7075T6 with Glass-Fiber-Reinforced Polyamide Composite

Coatings ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 96
Author(s):  
Eneko Ukar ◽  
Jon Iñaki Arrizubieta ◽  
Mercedes Ferros ◽  
Maite Andres ◽  
Fernando Liebana
Keyword(s):  
Shear Strength ◽  
Glass Fiber ◽  
Critical Factor ◽  
Cost Effective ◽  
High Dispersion ◽  
Fiber Reinforced ◽  
Dissimilar Joining ◽  
Aspect Ratios ◽  
Laser Joining ◽  
Glass Fiber Reinforced

Dissimilar joining between metal and composite sheets is usually carried out by mechanical or adhesive joining. Laser dissimilar joining between metal and composite sheets could be an alternative to these methods, as it is a cost-effective and versatile joining technique. Previously, textured metallic and composite parts have been held together and heated with a laser beam while pressure is applied to allow the melted polymer to flow into the cavities of the metal part. The main issue of this process relates to reaching the same joint strength repetitively with appropriate process parameters. In this work, both initial texturing and laser joining parameters are studied for Al 7075-T6 and glass-fiber-reinforced PA6 composite. A groove-based geometry was studied in terms of depth-to-width aspect ratio to find an optimal surface using a nanosecond fiber laser for texturing. Laser joining parameters were also studied with different combinations of surface temperature, heating strategy, pressure, and laser feed rate. The results are relatively good for grooves with aspect ratios from 0.94 to 4.15, with the widths of the grooves being the most critical factor. In terms of joining parameters, surface reference temperature was found to be the most influential parameter. Underheating does not allow correct material flow in textured cavities, while overheating also causes high dispersion in the resulting shear strength. When optimal parameters are applied using correct textures, shear strength values over 26 kN are reached, with a contact area of 35 × 45 mm2.

Fracture Strength of Various Types of Large Direct Composite and Indirect Glass Ceramic Restorations

2019 ◽  
Vol 44 (4) ◽  
pp. 433-442 ◽  
Author(s):  
MCFM de Kuijper ◽  
MMM Gresnigt ◽  
M van den Houten ◽  
D Haumahu ◽  
U Schepke ◽  
...  
Keyword(s):  
Glass Fiber ◽  
Fracture Strength ◽  
Lithium Disilicate ◽  
Control Group ◽  
Fiber Post ◽  
Fiber Reinforced Composite ◽  
Composite Restorations ◽  
Reinforced Composite ◽  
Glass Fiber Reinforced ◽  
Glass Fiber Post

SUMMARY Introduction: The objective of this study was to investigate the mechanical behavior of severely compromised endodontically treated molars restored by means of various types of composite buildups, full-contour lithium disilicate crowns (with or without post) or a lithium disilicate endocrown. Methods and Materials: One hundred five sound molars were endodontically treated and randomly assigned to 1 control group (endodontic access cavity only) and 6 experimental groups (n=15): glass fiber reinforced composite (GFRC group), direct microhybrid composite (C group), direct microhybrid composite restoration with glass fiber post (CP group), composite buildup and full-contour lithium disilicate crown (LDS group), additional glass fiber post (P-LDS group), and endocrown (EC group). Molar crowns in the treatment groups were removed 1 mm above the cementoenamel junction and restored. All specimens were thermomechanically aged (1.2×106 cycles at 1.7 Hz/50N, 8000 cycles 5°C to 55°C) and axially loaded until failure. Data were analyzed using analysis of variance and Tukey post hoc test (α=0.05). Results: Fracture strength was significantly affected by the type of restoration (p=0.000; statistically similar groups identified with superscript letters): LDSB (3217±1052 N), P-LDSAB (2697±665 N), ECAB (2425±993 N), CA (2192±752), controlA (1890±774 N), CPA (1830±590 N), and GFRCA (1823±911 N). Group GFRC obtained significantly more repairable fractures than the other groups. Conclusions: Significant differences in fracture strength were obtained between LDS, the composite restorations, and control group. Direct composite restorations showed similar fracture strength as P-LDS and EC. Incorporating a glass fiber reinforced composite resulted in significantly more repairable failures.

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.

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