Modulus Carbon Fiber Reinforced Polymer Research Articles

Modelling and Analysis of CNC Milling Machine Bed with UHM CFRP composite Material

Abstract: Structural materials are used in a machine tool have a key role in defining the productivity, accuracy and Size proportions of the part manufactured by machine tool. The conventional structural materials like cast iron and Stainless or carbon steel at high operating speeds but used in precision machine tools grow positional errors due to the vibrations transferred into the Machine tool structure. Faster cutting speeds can be achieve only by structure which has good damping characteristics and high stiffness. Clearly the life of a machine tool is proportional to the levels of vibration Produce by machine. The further Work is carried out to Study the deformation and natural frequency using Static analysis and Modal analysis respectively. The bed in machine tool Took Major role in the precision in components. It is one of the greatest vital tool structures which is absorb the vibrations resultant from the cutting operation. To analyse the bed for possible material changes and Structure changes that could increase stiffness, decrease weight, expand damping characteristics and segregate natural frequency at the operating range. So main enthusiasm behind the impression to go for a composite Material in model involving ultra-High Modulus Carbon Fibre Reinforced Polymer Composite Material (UHM CFRP). In a carbon has good stiffness and strength properties but its absences in damping requirements. On the other hand, polymers, though its deficiencies in strength but, good damping in characteristics and it is easily holding the carbon fibres. So, this is makes greatest combination of materials in an appropriate manner. In this work, a machine tool’s bed is selected for the analysis static loads. Then study is carried out to decrease the weight of the machine tool’s bed without affecting its structural rigidity. The 3D CAD model of the bed has been created by using commercial 3D modelling software and analyses were carried out using ANSYS 2021 R2. Keywords: Composite material, hybrid structures, Milling machine bed, UHM CFRP.

Compressive strength determined for ultrahigh modulus fiber reinforced composites by [90/0]ns laminates

Traditional ASTM D6641 standard is not suitable for ultrahigh modulus carbon fiber reinforced polymer (CFRP) composites under longitudinal compression due to the unacceptable failure mode of end crushing. Experiments and micro-mechanical finite element simulations are conducted for [90/0]ns laminates under compression to check if it is acceptable using results of [90/0]ns laminates to calculate longitudinal compressive strength. Experimental results show that failure modes in [90/0]ns laminates are acceptable. Fiber splitting, fiber breakage and kink band are found clearly in 0-degree lamina under SEM. Failure index distributions before peak load in simulation show that it is fiber failure in 0-degree lamina that causes the final failure which indicates that [90/0]ns laminates can be used to calculate compressive strength. Four different types of fibers with different modulus and [0/90]ns micro-mechanical model for ultrahigh modulus CFRP are also built for comparison. Results show that this method is also applicable for T800H CFRP composites, but not for T300 and T700 CFRP composites.

Fatigue improvements of cracked rectangular hollow section steel beams strengthened with CFRP plates

Concerns over means to improve fatigue behavior of cracked rectangular hollow section (RHS) steel beams exist. This paper presents the details of strengthening schemes that was carried out using prestressed or high modulus carbon fiber reinforced polymer (CFRP) plates. A set of fatigue tests were conducted and results indicated that prestressed CFRP technique could increase fatigue crack propagation life 35.57 times longer than that of unrepaired one. The results also indicated that high modulus CFRP is effective at increasing fatigue life. Following crack propagation lives were calculated based on finite element models and close agreement with test results were observed. Thereafter, a parametric study was conducted considering the influence of various parameters such as the CFRP prestressing level, plate width and modulus on the fatigue life of the strengthened specimens. The findings of this paper can be employed to formulate design guidance for RHS beams under fatigue loading.

Transient Thermal Tensile Behaviour of Novel Pitch-Based Ultra-High Modulus CFRP Tendons.

A novel ultra-high modulus carbon fibre reinforced polymer (CFRP) prestressing tendon made from coal tar pitch-based carbon fibres was characterized in terms of high temperature tensile strength (up to 570 °C) with a series of transient thermal and steady state temperature tensile tests. Digital image correlation was used to capture the high temperature strain development during thermal and mechanical loading. Complementary thermogravimetric (TGA) and dynamic mechanical thermal (DMTA) experiments were performed on the tendons to elucidate their high temperature thermal and mechanical behaviour. The novel CFRP tendons investigated in the present study showed an ambient temperature design tensile strength of 1400 MPa. Their failure temperature at a sustained prestress level of 50% of the design tensile strength was 409 °C, which is higher than the failure temperature of most fibre reinforced polymer rebars used in civil engineering applications at similar utilisation levels. This high-temperature tensile strength shows that there is potential to use the novel high modulus CFRP tendons in CFRP pretensioned concrete elements for building applications that fulfill the fire resistance criteria typically applied within the construction industry.

The Effect of Elevated Temperature on the Bond Between High Modulus Carbon Fibre-Reinforced Polymer Sheet and Steel

The technique of strengthening steel structures with carbon fibre-reinforced polymer (CFRP) has attracted growing attention in research field and in practice, and thus, its environmental durability is of high importance. This paper describes an investigation on the bond characteristics between high modulus CFRP sheets and steel plates under elevated temperature exposures. Tensile tests were carried out on CFRP/steel plate double strap joints at different temperatures (20,40 and 50 °C) that represent the usually encountered conditions for civil infrastructure. High modulus (640 GPa) unidirectional carbon fibre sheets were applied by wet lay-up fabrication method. The fracture surfaces of the failed specimens were studied using a scanning electron microscope and the failure mechanisms were discussed. It was found that the ultimate load decreased significantly when the test temperature was above the glass transition temperature of the adhesive. Larger effective bond lengths were found for the joints tested at the glass transition temperature. It is obvious that the short-term thermal exposure has little effect on their failure patterns. All the specimens failed by fibre breakage at the joint and decohesion accompanied some joints with very short bond length.

Fatigue tests on steel plates with longitudinal weld attachment strengthened by ultra high modulus carbon fibre reinforced polymer plate

ABSTRACTWelded steel connections of infrastructures are susceptible to fatigue failure. Advanced carbon fibre reinforced polymer (CFRP) has been demonstrated promising for fatigue strengthening of steel structures. Limited research was conducted on CFRP strengthening of welded connections. This paper focuses on the application of ultra high modulus (UHM) CFRP plates with a modulus of 460 GPa to strengthen steel plates with longitudinal fillet weld attachment using five CFRP strengthening configurations. A series of fatigue tension tests were carried out with constant amplitude fatigue loading. Beach marking technique was adopted to record the crack propagation process. Effects of CFRP bond length, bond width and bond locations on fatigue performance of welded steel joints were investigated. The experimental results showed that UHM CFRP plates could generally increase the fatigue life of the welded steel joints. It seems better to apply CFRP on the welding side of the specimen to achieve longer fatigue life. Then, the effects of weld and weld attachment on the CFRP strengthening efficiency was further studied by comparing experimental results of non‐welded steel plates with single side UHM CFRP plate strengthening. Finally, the classification method was adopted to assess the strengthening efficiency of the UHM CFRP plate to the steel plates with longitudinal weld attachment.