View non-flash version
ensure that the tasks involved in creating a FEM don't outweigh its benefits. The inspection of the drydock during which plates and members throughout the struc- ture are gauged must be thorough yet lim- ited, since such a process can easily become all-consuming. The key to the gauging inspection is to define an appro- priate and rational measurement matrix prior to the inspection. The plan will focus the survey effort on the areas of the struc- ture that are most critical, rather than tak- ing a blanket or random testing approach. The ultrasonic testing matrix for a dry- dock would specify gauging at more fre- quent intervals of members primarily con- tributing to the primary strength and members that are directly in the path of the docking loads. Typically this would include bottom shell and deck plate, gird- ers, web frames, bulkheads, and stan- chions near the centerline. Areas of less importance to the global strength of a dock will be gauged at fewer locations. These areas may include stiffeners, frame flanges, trusses off centerline, and sideshell, depending on the drydock design. The sheer volume of data collect- ed and input into the modeling program must be identified and managed before the structural evaluation begins. Comput- er memory requirements are proportional to the database size, which in turn is dependent on the number of elements and the size of the element properties library. Additionally, file save, display regenera- tion, and solution times grow exponential- ly with increases in database size, so it is preferable to keep the database size to a minimum without compromising the accuracy of the results. Future Uses Creation of a finite element model to address corrosion in drydocks is useful not only for immediate repair needs, but also for addressing future maintenance issues and corrosion control criteria. The repair matrix provides the owner's mainte- nance group with an invaluable record for future reference. The maintenance group can refer to the repair matrix before carry- ing future thickness gauging measure- ments to determine which areas require more attention. After future thickness gauging measurements are carried out, it is relatively easy to incorporate the results into the existing FEM and determine if further repairs are necessary. At EBDG we have found that when properly executed, emerging FEA tech- nology can be used to manage the mainte- nance of the drydock to optimize repair effort and minimize costs. 26 • MarineNews • August, 2005 MARINE ENGINEERING Circle 218 on Reader Service Card ? meets the latest Coast Guard Standards ? Up to 30 days sidelight usage & Up to 160 days special flashing usage on HDM spring type batteries ? Top case & Name plate color coded for ease in installation ? Capable of operating on 1 o 4 HDM Spring type bat- teries ? External stainless- steel hardware throughout “See the Difference” EMPCO-LITE, DIVISION OF ELGIN MOLDED PLASTICS WWW.EMPCO-LITE.COM FAX: 847-931-2454 CALL TOLL FREE 800-548-5483 MANUFACTURERS ALSO OF: MOORING LIGHTS, DREDGE LIGHTS, TRI-CHARGER, ALL ROUND LIGHTS, DOMED WARNING LIGHTS, ANCHOR LIGHTS, LONG TOW OPTIONS MARINE DIVISION OF ELGIN MOLDED PLASTICS CO. LED NAVIGATIONAL BARGE LIGHTS Circle 210 on Reader Service Card SNAME Introduces Innovation Sessions In response to feedback from exhibitors, SNAME will introduce Innovation Ses- sions during the SMTC&E and SPS, scheduled to be held in Houston on October 20-21, 2005. Exhibitors who have new products or technologies can use these ses- sions to make presentations to SMTC&E and SPS conference attendees in a special lecture-style area of the Expo Hall with seating for up to 30. Details: 20-minute segments, with 10 minutes for Q&A, for a total of 30 minutes maximum per session. Time slots available are: Thursday, October 20 - 12:30 pm - 2:00 pm and 4:00 pm - 4:30 pm Friday, October 21 - 8:30 am - 9:30 am and 12:30 pm - 3:30 pm Although these presentations will not be formally reviewed, SNAME must reserve the right to refuse any that do not seem appropriate, and will rely on the exhibitor's and presenter's own standards of professional behavior to make close supervision unnecessary. Brief abstracts must be submitted to SNAME HQ to enowak@sname.org. As there are only twelve slots available, they will be on a first come, first served basis. You will receive a confirmation after your abstract has been received. Two additional presentations will be selected as standbys. AUGUSTMN2005 4(25-32).qxd 8/1/2005 4:45 PM Page 26
