Development of a modified Mooney-Rivlin constitutive model for rubber to investigate the effects of aging and marine corrosion on seismic isolated bearings

In this study, aging and marine corrosion tests of a large number of rubber material and rubber bearings have been carried out. The constitutive Mooney-Rivlin model parameters for a rubber isolated bearing have been determined. By applying the least-square method to the experimental data, the relationships between the aging time and the marine corrosion time with the constants in the constitutive model for a rubber beating have been derived. Next, the Mooney-Rivlin model has been modified accordingly. Further, using the modified Mooney-Rivlin model and the Abaqus software, the performance of the rubber isolated bearings has been simulated. The simulation results have been compared to the experimental results so as to verify the accuracy of the modified model. The comparison shows that the maximum errors for the vertical and horizontal stiffnesses are 16.8% and 0.49%, respectively. Since these errors are considered acceptable, the accuracy of the modified constitutive model can be considered verified. The results of this study can provide theoretical support for the performance study on rubber isolated bearings under the complex ocean environment and the life-cycle performance evaluation of bridges and other offshore structures.

Microbial communities present on mooring chain steels with different copper contents and corrosion rates

Copper has long been utilized as a disinfectant for bacteria,but its impact on microbial communities attached to the steel surface in seawater remains unknown.In the present study,3 mooring chain steels of different copper contents are subjected to a 3-month marine field exposure,and the corrosion rate increases in the order of BR5 steel(without copper)<BR5 CuH steel(0.8%copper)<BR5 CuL steel(0.4%copper).The microbial community results show that copper introduction does not result in an obvious change in microbial quantity,but it alters the diversity,richness,and structure of microbial communities due to the variation in copper-resistance of different species.BR5 CuH steel holds microbial communities with the highest percentage of some well-known corrosive microbes including sulfate-reducing bacteria,sulfuroxidizing bacteria,and iron-oxidizing bacteria,but possesses the lowest community diversity/richness owing to the toxicity of copper.The microbial community diversity/richness is stimulated by the low-copper content of BR5 CuL steel,and this steel also carries an intermediate proportion of such corrosive bacteria.Both well-known corrosive bacteria and microbial community diversity/richness seem to be involved in the corrosion acceleration of copper-bearing mooring chain steels.

Expired drugs as vapor-phase corrosion inhibitors of copper in simulated marine atmospheric environment

Urea,paracetamol and glutamine(based on the expired drugs)were selected as vapor-phase corrosion inhibitors(VCIs)to study their corrosion protection effect on red copper in simulated marine atmospheric environment by using weight loss,electrochemical measurement techniques(specially designed electrochemical testing device for simulating marine atmospheric environments)and surface morphology characterization analysis(SEM/EDS,XRD,RAMAN,XPS).Weight loss results show that the three corrosion inhibitors have good corrosion inhibition effect on red copper,and the corrosion inhibition efficiency in the order of glutamine(83.62%)>urea(68.46%)>paracetamol(61.47%).Surface morphology characterization analysis provides evidence of adsorption of corrosion inhibitors molecules on the red copper surface,thus forming a protective film that blocked the red copper surface from the aggressive chloride ion attack.

Effect of cathode protection on Desulfovibrio desulfuricans corrosion of X80 steel in a marine tidal environment

The study systematically investigated the impact of zinc sacrificial anode(Zn-SA)cathode protection on the corrosion of X80 steel caused by Desulfovibrio desulfuricans(D.desulfuricans)in a marine tidal environment.Utilizing weight-loss analysis,electrochemical measurements,Raman spectroscopy,and 3D morphology microscopy,the research unveiled significant findings.Unprotected steel suffered pronounced localized corrosion in the presence of D.desulfuricans in the marine tidal environment.However,the implementation of Zn-SA cathode protection notably reduced the activity of both planktonic and sessile D.desulfuricans cells.Over time,the accumulation of calcareous deposits within the corrosion products increased,as evidenced by a rise in the resistance of the corrosion produt film(Rf).Remarkably,Zn-SA cathode protection demonstrated substantial inhibition of the steel’s corrosion rate,albeit exhibiting reduced efficiency as the vertical height of the steel within the tidal environment increased.

Rare earth lanthanum pinning effect for corrosion resistance ultraefficient microwave absorption FeCo@rGO composites

Magnetic metal absorbers exhibit remarkable microwave absorption capacity.However,their practical application is severely limited due to their susceptibility to corrosion,particularly in marine environ-ments.To address this challenge,we propose a novel approach involving the modification and control of FeCo/rGO microwave absorbers using rare earth lanthanum(La).This strategy aims to achieve both high-performance microwave absorption and enhanced resistance to marine corrosion.In this study,we employ a La_(2)O_(3) modifying control strategy to refine the FeCo magnetic particles and coat them with CoFe2O4 on the surface,leveraging the pinning effect of in situ generated La_(2)O_(3) .This process enhances the interface polarization of the absorbers,thereby improving their electromagnetic performance and ma-rine corrosion resistance.Consequently,the La_(2)O_(3) modified FeCo@rGO composites exhibit broadband ab-sorption,covering a wide frequency range of 6.11 GHz at 1.55 mm.Notably,the electromagnetic proper-ties of the La_(2)O_(3) modified FeCo@rGO absorbers remain stable even after prolonged exposure to a 3.5 wt%NaCI solution,simulating marine conditions,for at least 15 days.Furthermore,we perform first-principle calculations on FeCo and FeCo-O to validate the corrosion resistance of the La_(2)O_(3) modified FeCo@rGO composites at the atomic level.This comprehensive investigation explores the control of rare earth lan-thanum modification on the size of magnetic metal particles,enabling efficient electromagnetic wave absorption and marine corrosion resistance.The results of this study provide a novel and facile strategy for the control of microwave absorbers,offering promising prospects for future research and development in this field.

Protection Performance of Plasma Sprayed Al_(2)O_(3)-13 wt%TiO_(2) Coating Sealed with an Organic-inorganic Hybrid Agent

An organic-inorganic hybrid sealing agent was fabricated and used in the plasma sprayed Al_(2)O_(3)-13 wt%TiO_(2)coating,and conventional silicone agent was also used for comparison.Protection performance of the coatings was comprehensively evaluated based on both anti-corrosion and anti-biofouling properties.The results reveal that the sealing treatment is remarkably useful to decrease the porosity of the coating,and the porosity of the coating sealed with the hybrid agent is only 0.035%.Immersion corrosion test and Tafel polarization test reveal that the sealed coating with the hybrid agent exhibits a better corrosion resistance by compared with the coating sealed with silicone agent.The corrosion current density i_(corr) of the hybrid agent sealed coating is only 0.7×10^(-6)A·cm^(-2).Moreover,anti-biofouling tests both in the outdoor analogue hydraulic environment and in the natural marine environment prove that the mentioned novel coating presents a better combination of corrosion resistance and anti-biofouling property by compared with the other coatings,and it could be used as a protection of metal components in the marine environment.

Review of Ultimate Strength Assessment of Ageing and Damaged Ship Structures

The objective of this work is to provide an overview of the ultimate strength assessment of ageing and damaged ship structures in the last decades.Particular attention is paid to the ultimate strength of plates,stiffened panels,box girders,and entire ship hull structures subjected to corrosion degradation,fatigue cracking,and mechanical damage caused by accidental loading or impact.A discussion on the effect of the cyclic load on the plate rigidity,re-yielding,and ultimate load capacity on the ship hull girder is also part of the present study.Finally,some conclusions and discussions about potential future work are provided,identifying that more studies about the impact of corrosion degradation on the structural behaviour of the stiffened panels and the overall hull girders are needed.Studies related to the dynamic collapse behaviour of corroded and damaged ship structures under time-variant load also requires additional attention.