scholarly journals LIGHTENING STRUCTURES BY METAL REPLACEMENT: FROM TRADITIONAL GYM EQUIPMENT TO AN ADVANCED FIBER-REINFORCED COMPOSITE EXOSKELETON

2021 ◽  
Vol 19 (2) ◽  
pp. 155
Author(s):  
Cristiano Fragassa
Keyword(s):  
Composite Laminates ◽  
Volume Ratio ◽  
Kinematic Chain ◽  
High Strength ◽  
Failure Criteria ◽  
Maximum Principal Stress ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Reinforced Polymers ◽  
Strain Behavior

A redesign procedure used for introducing new functional properties in innovative gym equipment is here reported. It is based on a metal replacement action where a tempered steel was firstly replaced by an aluminum alloy and then by high strength-to-weight fiber-reinforced polymers. The effect of fiber properties (as strength and volume ratio) and plies stacking sequences (as thicknesses and orientation) were investigated. Numerical analyses, done by Ansys ACP, allowed evaluating the stress-strain behavior in realistic boundaries and quasi-static loads, comparing materials and layouts in terms of stiffness. The single-layered shell method with additional integration points was preferred as a technique for discretizing composite laminates. Maximum Principal Stress and Maximum Distortion Energy (Tsai-Hill) were applied as anisotropic failure criteria. Changes in geometry were also considered given their relevant effects on parts and processes. Specifically, this paper is focused on a representative component of the main kinematic chain (the ‘forearm’) and details the different redesign phases for that part. The chosen solution consisted of 14 layers of unidirectional and bidirectional carbon fiber-reinforced pre-pregs, offering a 68 % weight reduction with respect to a solid aluminum component with equal stiffness. The part was manufactured by hand lay-up and cured in autoclave. This redesign practice was extended to the rest of the equipment allowing its transformation into an exoskeleton.

Optimum Design of Composite Pressure Vessel Based on 3-Dimensional Failure Criteria

2019 ◽  
Author(s):  
J. Sakai ◽  
Y. H. Park
Keyword(s):  
Optimum Design ◽  
Pressure Vessel ◽  
Composite Laminates ◽  
Three Dimensional ◽  
Weight Ratio ◽  
High Strength ◽  
Failure Criteria ◽  
Pressure Vessels ◽  
Fiber Reinforced ◽  
3D Elasticity

Abstract Anisotropic composite cylinders and pressure vessels have been widely employed in automotive, aerospace, chemical and other engineering areas due to high strength/stiffness-to-weight ratio, exceptional corrosion resistance, and superb thermal performance. Pipes, fuel tanks, chemical containers, rocket motor cases and aircraft and ship elements are a few examples of structural application of fiber reinforced composites (FRCs) for pressure vessels/pipes. Since the performance of composite materials replies on the tensile and compressive strengths of the fiber directions, the optimum design of composite laminates with varying fiber orientations is desired to minimize the damage of the structure. In this study, a complete mathematical 3D elasticity solution was developed, which can accurately compute stresses of a thick multilayered anisotropic fiber reinforced pressure vessel under force and pressure loadings. A rotational variable is introduced in the formalism to treat torsional loading in addition to force and pressure loadings. Then, the three-dimensional Tsai-Wu criterion is used based on the analytical solution to predict the failure. Finally, a global optimization algorithm is used to find the optimum fiber orientation and their best combination through the thickness direction.

Behavior of Rectangular Concrete Column Confined with Sisal Fiber Reinforced Polymers (Sisal FRP)

2016 ◽  
Vol 860 ◽  
pp. 140-143 ◽  
Author(s):  
Atipphat Suwattanakorn ◽  
Qudeer Hussain ◽  
Winyu Rattanapitikon ◽  
Amorn Pimanmas
Keyword(s):  
Research Work ◽  
Testing Machine ◽  
High Strength ◽  
Fiber Reinforced Polymers ◽  
Sisal Fiber ◽  
Fiber Reinforced ◽  
Concrete Core ◽  
Reinforced Polymers ◽  
Rectangular Columns ◽  
Strength And Ductility

This research work presents the results of experiment study on the axial behavior of low-high strength concrete rectangular columns confined by Sisal Fiber Reinforced Polymers (Sisal FRP). The objective of this study is investigate the performance of Sisal FRP composites to increase strength and ductility of rectangular columns through external confinement. The research parameter were confinement thickness and strength of concrete core. A total of 16 rectangular columns were tested under Universal Testing Machine (UTM) up to failure point. Test result shown that the external confinement by Sisal FRP are very effective to increase strength and ductility.

scholarly journals Experimental investigation on stiffness and strength of single-lap z-pinned joints in a laminated CFRP stress-ribbon strip

2016 ◽  
Vol 11 (2) ◽  
pp. 120-126 ◽  
Author(s):  
Aleksandr K. Arnautov ◽  
Vladimir Kulakov ◽  
Janis Andersons ◽  
Viktor Gribniak ◽  
Algirdas Juozapaitis
Keyword(s):  
Structural Integrity ◽  
Progressive Failure ◽  
Failure Process ◽  
High Strength ◽  
Lap Joints ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Reinforced Polymers ◽  
Load Bearing ◽  
Hybrid Joints

Carbon fiber-reinforced polymer (carbon-polymer) is an advanced lightweight composite material with high strength and excellent resistance to corrosion and fatigue. Over the past decades, application of fiber-reinforced polymers has been spread from the aerospace to other branches of industry such as automobile and civil engineering. Unidirectional carbon-polymers have a high potential for replacing steel in tensile members. Recently, the first carbonpolymer stress-ribbon bridge has been constructed in Germany. The non-laminated strip-loop carbon-polymer thin strips were used as the load bearing components in this bridge. In comparison with the laminated components, the applied cables are characterized by a more uniform strain distribution though reduced structural integrity. Alternative jointing technologies of carbon-polymer laminates are considered in this paper with an intention to increase the structural integrity and reliability of the production. Tensile behavior of the single-lap joints was investigated experimentally. Three types of the joints were considered. Adhesive joint was set as the reference. The overlap region of the mechanically fastened joints was produced using 9, 25, or 36 steel needles (z-pins) of 1 mm diameter. The proposed hybrid joints were additionally connected with adhesive increasing the load-bearing capacity of the reference joint up to 230%. Concerning the brittle fracture of the adhesive counterparts, the extended progressive failure process within the hybrid joints is responsible for the improvement.

Mechanical Properties of Structural Paper-Polypropylene Composite Laminates

2015 ◽  
Vol 825-826 ◽  
pp. 11-18 ◽  
Author(s):  
Martina Prambauer ◽  
Christian Paulik ◽  
Christoph Burgstaller
Keyword(s):  
Mechanical Properties ◽  
Composite Laminates ◽  
Natural Fiber ◽  
Glass Fibers ◽  
Cellulose Fiber ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Reinforced Polymers ◽  
Polypropylene Composites ◽  
Flexural Testing

Natural fiber reinforced polymers have gained increasing interest in research with the aim of replacing conventional reinforcements, such synthetic or glass fibers. In this work, whole paper sheets of copy, filter and newspaper were used for fabricating cellulose fiber reinforced polypropylene composites with MAPP as a coupling agent. By varying the amount and type of paper, the influence of these parameters on the mechanical properties was observed. The laminates were produced by a film hand stacking method and hot pressing. The characterization was carried out by tensile and flexural testing. Remarkable results were obtained for copy and newspaper composites at a fiber content of 30 and 40 vol.-%. In summary, structural paper reinforced composites with attractive mechanical properties were obtained, indicating the high potential of whole paper sheets as polymer reinforcement.

scholarly journals Maintenance and Inspection of Fiber-Reinforced Polymer (FRP) Bridges: A Review of Methods

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7826
Author(s):  
Long Tang
Keyword(s):  
Building Materials ◽  
High Strength ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Reinforced Polymers ◽  
Reinforced Polymer ◽  
Static And Dynamic Loads ◽  
Potential Damage ◽  
Maintenance And Inspection

Fiber-reinforced polymers (FRPs) are materials that comprise high-strength continuous fibers and resin polymer, and the resins comprise a matrix in which the fibers are embedded. As the technique of FRP production has advanced, FRPs have attained many incomparable advantages over traditional building materials such as concrete and steel, and thus they play a significant role in the strengthening and retrofitting of concrete structures. Bridges that are built out of FRPs have been widely used in overpasses of highways, railways and streets. However, damages in FRP bridges are inevitable due to long-term static and dynamic loads. The health of these bridges is important. Here, we review the maintenance and inspection methods for FRP structures of bridges and analyze the advantages, shortcomings and costs of these methods. The results show that two categories of methods should be used sequentially. First, simple methods such as visual inspection, knock and dragging-chain methods are used to determine the potential damage, and then radiation, modal analysis and load experiments are used to determine the damage mode and degree. The application of FRP is far beyond the refurbishment, consolidation and construction of bridges, and these methods should be effective to maintain and inspect the other FRP structures.

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