Machine Design and Mechanisms

In addition to FEA, Kinematic Modeling is a powerful tool in evaluating loads and mechanical response through a mechanism's entire range of motion. It also allows factors such as friction and tolerances to be examined more closely. However, it is far from the only tool KES has in addressing machine design and mechanisms. The bottom line is providing a timely cost-effective solution for the client

Redesign of Power Transmission:  A series of linkages taking power from a gear reducer to actuator shaft via a four bar linkage and rocker experienced failures on one application and provided insufficient power in another. KES used 3-D kinenematic modeling and FEA to identify the root cause of the problems, then worked with their staff to redesign the linkage to address both issues.

Shallow Draft Crane Bucket Kinematic Review:  A crane bucket was designed to attack with a wide but shallow bite for loose material with a low angle of repose; however, the bucket had difficulty with a specific material. KES used a 2-D kinematic model to examine the digging action and recommend courses of action for the OEM.

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Bearing Review for Variable Loading:  A rotating equipment item was designated for use on an elevated structure where wind and ice loads would be significant. KES modeled the item using solid modeling and 3-D kinematic modeling to apply the wind, ice, and dead loads to determine the bearing loads, then evaluated the bearing loads to determine if they met the end client specifications. The image below shows the various traces of applied force, reaction forces, torques, and other responses as the structure goes through its full range of motion under specified loads. These results can then be transferred to a Finite Element model for to examine stress, deflections, strain, deflections, and other responses.

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Offshore, Oil field, Marine

Offshore, oil field, and marine applications require more reliability and toughness than many other areas. The middle of a computer analysis run is the last place you can afford to have something go wrong.

Diving Bell Certification for US Coast Guard:  A diving bell required re-certification by the US Coast Guard. The initial ASME Section VII, Div. 1 and Pressure Vessel for Human Occupancy (PVHO) analysis significantly downgraded the allowable depth. KES performed a ASME Section VII, Div. 2 analysis to examine the structural response with greater detail, accuracy, and precision than Div. 1 provides in conjunction with an on-site inspection and review of UT results. The more detailed analysis indicated the diving bell could be used reliably at a greater depth than originally indicated, allowing the end client use the bell for more sites. The report was reviewed and fully accepted by the USCG.

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Topsides Equipment Fatigue Evaluation:  A series of equipment items on different vessels needed to be evaluated for fatigue. Operational loads such as temperature and pressure were evaluated, as well as loads due to vessel movement while underway, stationary, and towed. A 30 year target life was required with different safety factors based on specific applications. Traditional calculations were conducted along with linear, nonlinear, and fatigue modeling using FEA. ASME code was used for some equipment items, PD5500 for others. Based on results some items were recommended for changes such as adding repads or increasing plate thickness. The image below is a section of a hydrocyclone modeling on the inertia-based forces due to the vessel action on the hydrocyclone contents. Subsequent runs evaluated pressure effects. The fatigue analysis used the cumulative damage theory to examine the stresses, determine to what degree the various stress states are alternating at each node, and calculates a useful life based on the number of cycles estimated per year.

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Fabrication and Structural

Rolled Section for Stairway:  An architect had designed a helical stairway for a shopping center, with the risers attached to a central pipe as well as an OSHA-required flat landing halfway up the stair. The structural engineering firm for the project determined the pipe needed to be 8-inch XXH but the fabrication contractor could not find a firm that could provide 3-D bends for piping this heavy. Finally a fabrication company proposed to do a series of flat (2-D) bends, then rotate the sections during assembly to achieve the desired results. KES was tasked to break the pipe into appropriate sections, determine the bends, and then determine how to roll the sections during assembly. KES used the client-provided specifications and drawings as well as conferred with the various parties to determine the sections, then how to cut and assemble the sections, and issued drawings and data sheets to the pipe bending fabricator and the project's primary fabricator who would execute the erection of the finished sections. The end result was the creation of six sections.

Detailed Design for Extrusion Header:  A fabricator was given a challenge–design a plastic extrusion die based on an existing octagonal extruder with a given hole diameter and density, ensure the correct range of  number of holes are in the appropriate area of the assembled bottom side, and ensure there quality control measures are met. The holes had to be drilled in flat plate, then the plate had to be rolled into shape to make the individual sections, then the sections had to be assembled and welded with a close fit. KES developed the design, including a Finite Element Analysis of the extruder to ensure the structural strength was sufficient, and with the end client's approval developed the flat patterns, to include the regions for drilling. The entire project was completed without any errors, all parts fit within a 1/8 inch tolerance, and the extrusion header has performed reliably since it was installed.

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Navigation Light Structure:  A state Dept. of Transportation required structural calculations showing the support structure for bridge mounted navigation lights met specifications for wind, ice, and vibration loads. KES developed a beam-element FEA model to determine the structure's response. The state DoT reviewed the report, approved the results, and purchased the navigation light system.