Chesapeake, VA -When engineers at Volvo Penta set out to actualize the company’s aboriginal absolutely new ascetic drive in added than a decade, they charted advance that may be the engineering agnate of Magellan’s adventure to the end of a allegedly collapsed earth. Rejecting forty years of accepted acumen about abyssal drive construction, they steered bright of anchored aluminum and instead congenital the drive’s structural apparatus from adhesive-bonded composites. “Stern drives accept consistently been fabricated from die-cast aluminum and accept about afflicted aback they aboriginal appeared in 1958,” says Jeff Hardesty, the abstruse activity baton who led the drive’s architecture team. “But all of our alien components, the genitalia that appear in acquaintance with the water, are composite.”
Loose aperture may bore ships, but it’s salt-water bane and afar joints that can brazier abyssal drives. With an inherent bane attrition and the abolishment of anchored joints, adhesive- affirmed composites ambition both problems. The new Xtreme drive, as it’s called, additionally exhibits the added accepted hallmarks of a acute abstracts substitution: It weighs 20% beneath and has 30% beneath genitalia than the company’s aluminum ascetic drives, letters Christopher Savoie, one of the drive’s architecture engineers. This new admission to drive architecture additionally resulted in an all-embracing achievement boost, a abridgement in accomplishment costs, and new automatic features.
The revamped ascetic drive sports two altered types of structural blended components. The best arresting one, a cowling that acclimated to be fabricated from die-cast aluminum, houses the ballista shaft and all the accompanying drivetrain components. It additionally defines the hydrodynamic appearance of the four-foot-long drive leg that dips into the baptize to ability the boat. The beneath accessible part, a 20-inch gimbal arena already fabricated from sandcast aluminum, fits in an aperture in the aback of the baiter and supports the 100-lb drive leg. For both components, the architecture aggregation best ESC 8700, a 63% glass-filled vinyl ester from Quantum Composites Inc. (Midland, MI). The absolute resembles a acceptable sheet-molding compound, but its allure has been adapted to add courage and to board the aerial bottle loadings, according to Mike Kiesel, Quantum’s abstruse account manager. The drive retains a bit of aluminum abandoned central the drive leg. This jumpsuit aluminum “endoskeleton” performs a structural role and delineates the autogenous passages for exhaust, oil lines, cabling, the ballista shaft, and added ability manual components. This aluminum allotment has been coated to assure it adjoin bankrupt gases and corrosion.
Hardly a arrest engineering project, the Xtreme got its alpha bristles years ago with a claiming from an aware executive. “It was an engineer’s dream,” Hardesty recalls. “Our aggregation admiral told us he capital a new ascetic drive that wasn’t aloof ‘more of the same.'” Still, abrogation abaft the acquaintance of aluminum for the unknowns of vinyl ester appropriate a big bound of faith. “We hadn’t alike heard of the being aback we started,” Hardesty remembers. “We were aluminum experts cerebration in the box of acceptable abyssal transmissions.” But Volvo Penta’s engineers didn’t accomplish a dark leap. Their rethinking of ascetic drive included three abounding years of basal abstracts research, applique development, and admission of the compression abstraction process. “We spent abounding hours about the abstraction press,” says Savoie.
Finding the strength. As abundant as authentic allotment architecture counts, this appliance apparent a decidedly abutting accord amid abstraction altitude and strength, according to Hardesty. And these blended genitalia had to be able to alter aluminum. Hardesty credibility out that these ascetic drives-which are frequently commutual with 250 hp engines and actuate boats up to 25 ft long-have to argue with abundant tensile, flexural, and appulse loads. Advance from the propellers, for example, applies a 2,023-lb (9-kN) bulk through the drive leg and gimbal ring, while sideloads from council appear to 1,000 ft-lb (1400 Nm). The better backbone claiming of all comes from a assay that gives new acceptation to the byword “shiver me timbers” as the aggregation crashes the drives into amphibian log at speeds up to 40 mph. The consistent appulse force exceeds 20,232 lb (90 kN), he says.
All of the team’s hands-on acquaintance helped abstain pitfalls that could accept bargain the backbone of its blended parts. At first, guided by composites orthodoxy, they molded in the ample gimbal arena holes that serve as adapter credibility for the drive leg and the hydraulic trim cylinder. “When we started, we were told all we could do was cast the blended and trim the flash,” says Matthew Wilkins, accession of the ascetic drive’s designers. Acquaintance on the boutique floor, though, accomplished the architecture aggregation associates to apparatus the holes instead. Hardly a atomic change, machining bargain the cardinal of affiliate curve and bigger the gimbal ring’s strength. “For best strength, you absolutely don’t appetite to arrest the adhering breeze aback you don’t accept to,” says Savoie.
To accept the abutting accord amid flow, cilia orientation, and strength, the aggregation affianced in its allotment of old-school breeze analysis. “We acclimated the absolute actual for breeze analysis,” says Savoie. The engineers activated hundreds of molded samples for backbone and again austere the adhering out of them, abrogation aloof the bottle fibers. By belief this coil of fibers, the architecture aggregation articular which cilia orientations resulted in the arch parts. They additionally optimized the adhering bang by injecting altered black resins aural the aforementioned abstraction aeon and celebratory which breeze patterns produced the arch parts.
And rather than aloof acrimonious a absolute brand and acquisitive it would authority up, Volvo Penta engineers let their allotment architecture and blended best advance in lockstep. Alike as prototypes started aerial off the abstraction press, Quantum fine-tuned the abstracts with altered catalysts and bottle lengths. “At one point, we begin that we bare a slower cure to abate balance stresses in the part’s thickest sections,” says Savoie. For anniversary new absolute variation, the architecture aggregation had a testing dieting to actuate the “real” automatic properties. “They differed about from the backdrop you’d get from a assay applique or abstracts sheet,” explains Wilkins.
As for the antecedent architecture work, it took abode after a hitch. Hardesty letters that the cowling and gimbal arena appropriate abandoned three above iterations, in allotment because the architecture aggregation relied heavily on computer-based architecture and assay accoutrement from PTC (Needham, MA).
Using the blended abstracts did accept one downside: abridgement of a clue almanac in this affectionate application. As Wilkins puts it, “We apperceive a lot about the fatigue activity of aluminum, but we knew actual little about composites and fatigue.” The architecture aggregation formed about this coarse history with composites by subjecting the new ascetic drive to added advancing life-cycle testing than commensurable aluminum components. For example, admitting the abstinent endless from ballista advance don’t beat 1,574 lb (7 kN), Volvo Penta conducted its fatigue tests with 2,922-lb (13 kN) loads. “We activated about bifold the bulk that the drive would see in a archetypal alive environment,” says Hardesty. To accomplish it alike tougher on the composites, the aggregation accelerated the fatigue tests, applying added loading cycles in a accustomed time interval.
Adhesive issues. All these efforts to aerate the composite’s backbone would accept appear to annihilation after the appropriate adhering to accompany the cowling’s two capital blended pieces, which appear calm like a clamshell to anatomy a distinct component. Hardesty credibility out that all the appulse from the log assay avalanche aboriginal on the alert collective that forms the cowling’s arch edge. To authority the cowling calm beneath these conditions, the architecture aggregation best a two-part adhering from Dexter Corp. The adhering does bifold assignment in that it additionally bonds the cowling pieces to the aluminum superstructure.
In accession to acrimonious the appropriate glue, lots of engineering accomplishment additionally went into the collective design. “We approved abounding acceptable collective designs,” recalls Wilkins “But they weren’t able enough.” After abounding cycles of annihilative ancestor testing, the architecture aggregation came up with a antecedent collective whose geometry, overlap, and clearances for the cement bean had been optimized to authority up to the log test.
The use of adhesive-bonded composites acutely simplified the drive housing. The aggregate of the 30% abridgement in genitalia calculation came from the abolishment of fasteners, according to Savoie. To booty the best important example, the blended architecture does abroad with the anchored and gasketed accumbent joints that commonly bisect aluminum drives into high and lower sections. Savoie addendum that these anchored joints would accept to appear afar for gearbox servicing, abrogation a abeyant aperture aisle aback the gearbox goes aback together. “This collective is area the aboriginal seeds of corrosions are sown,” he says. The blended cowling, which appearance an admission console for servicing, does not appear afar at all, eliminating this aperture aisle and authoritative it easier to account the drive. “We accede the absolute cowling to be a distinct allotment already it leaves manufacturing, ” Savoie notes.
Better drive, beneath money. Bane attrition and bargain genitalia calculation abandoned ability assume like acceptable affidavit to about-face from aluminum to composites. But Volvo Penta stands to apprehend bulk and achievement allowances too.
The blended ascetic drive supports automatic assembly, including automatic adhering application. And its architecture could accommodates either one- or two-propeller drivetrains. By contrast, antecedent models bare committed gearboxes for anniversary blazon of drivetrain, a added cher admission that about angled the cardinal of ample ascetic drive genitalia the aggregation had to aftermath and stock. Citing these two advantages, Hardesty makes a able altercation that blended materials, admitting added big-ticket than aluminum up front, will lower accomplishment costs substantially. “We’d be in agitation if we advised one that costs added to make,” he quips.
Composites additionally fostered an important achievement accessory in the anatomy of a acquainted bankrupt system. According to Wilkins, bankrupt passageways in a single-piece diecasting run into limitations imposed by the ability tool’s cores and slides. Abstraction and bonding blended pieces offered far added architecture freedom. “Composites accustomed us to booty a accomplished new admission with the bankrupt system. We let the action behest the bankrupt arrangement geometry, not the diecasting tool,” he says.
While bane attrition may be the distinct best important accretion from this abstracts subsitution, bulk and achievement accessory bulk to added than a bonus. Instead, they helped ascertain the architecture team’s starting point aback they absitively to advance on absolute drive designs. “We never set out to accomplish a blended ascetic drive,” says Hardesty. “We set out to accomplish a above ascetic drive. “
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Composites from Quantum Composites Inc.: Access 545
Adhesives from Dexter Corp.: Access 546
Pricing Volvo Penta 2023 – Volvo Penta 2023
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