ALUMINUM, steel, composites—each has their strengths and weaknesses as a material to use in manufacturing trailers. At the recent CTEA Manufacturers Conference, a forum of trailer manufacturers, each of whom specialize in using a specific material explained the advantages and disadvantages of their favorite material.
For Butch Medemblik, manager of engineering and plant operations for Walinga Inc and a past president of the Canadian Truck Equipment Association (CTEA), that means exploring material alternatives like composites.
Based in Guelph, Ontario, Canada, Walinga started trailer manufacturing in 1954, using the slogan “Building Any Body For Anybody.” Cornelius Walinga and John Medemblik began handcrafting wooden truck bodies for local businesses.
Throughout the decades as each new technological advancement became available, Walinga incorporated it into the manufacturing process. In 1955, Walinga built its first cattle and feed hauler. Walinga introduced grain vacuums in the late 1970s and was the first producer in North America to use a positive displacement system to transfer grains at a greater rate of speed with less horsepower, using smaller lines. The company also pursued the elimination of wind resistance by bringing the unit closer to the road and re-imagining protruding ribs and braces, and making better hydraulic systems and high-output augers so trucks run less, consuming less fuel.
Now it is moving into composites to drive unit weights down. Strength-to-weight ratios are important, as is a new material’s ability to withstand the trials of daily use.
“We are working with a third-party composites manufacturer and an innovations center,” Butch Medemblik said. “Most of our equipment hauls animal feed. We’re looking for ways we can make our customers more competitive. Through the years, there have been weight challenges. Aluminum is a big part of what we do, but with the advancement in composites we felt compelled to look at it in 2015.
“The application possibilities are wide and broad. It is important for each of us to keep looking forward. We manufacturers need to look for new ways so consumers can haul more payload and be safer to protect our operators and to be progressive. Composites are just one area to consider. The only constant today is change. Those of us who adapt will be in a better place to survive. That is part of the roadmap to success that the association is trying to promote.”
Why manufacturers should explore composites:
• Design flexibility. “Composites have an advantage over other materials because they can be molded into complex shapes at relatively low cost. The flexibility of creating complex shapes offers designers a freedom that is a hallmark of composites achievements.”
• Durability. “Composite structures have an exceedingly long life span. The longevity of composites, along with their low-maintenance requirements, is a major benefit in critical applications. There are many well-design composite structures constructed over 50 years ago that are still active today.”
• Corrosion resistance. “Composite products provide long-term resistance to severe chemical and temperature environments. Composites are often the material of choice for outdoor exposure, chemical handling applications, and severe environment service.”
• High strength. “Composite materials can be designed to meet the specific strength requirements of an application. A distinct advantage of composites over other materials is the ability to use many combinations of resins and reinforcements, and therefore to custom tailor the mechanical and physical properties of a structure.”
• Light weight. “Composites are material that can be designed to have light weight and high strength. In fact, composites are used to produce structures with the highest strength-to-weight ratio known to man.”
• Conductivity. “Composites have the characteristics to help reduce the risks due to electrocution. Trucks with booms or similar apparatus are often at risk.”
Medemblik said there is a great value proposition for composites, using examples of where they’re used in other industries. Composites are materials that can:
• Make bridges that don’t rust, and in the process double their lifespan.
• Make tanks that don’t leak gasoline into our groundwater and pipes that don’t leak and corrode, to deliver fresh water or take away sewage.
• Make boat hulls that don’t rot.
• Make vehicles better looking and more fuel-efficient.
He said the price of composites has come down dramatically, from $150 a pound in 1970 to less than $5 in 2008.
In terms of corrosion resistance, composites are great in chemical storage, where they displace stainless steel and exotic materials; sewer pipes, where they displace concrete, ductile iron, and clay; hog farrowing floors, where they displace concrete and wood; and concrete rebar, where they displace steel, stainless steel, and coated steel.
He said composites can lower costs in installation/shipping, maintenance/repair, and manufacturing.
In manufacturing, that comes in the form of parts consolidation, the facilitation of complex shapes, the support of a wide range of production rates from one to thousands, and low investment costs in equipment and tooling.
Considerations when planning to use composites:
• Composites are simply another material system.
• Like any material, they are not the best solution for all product applications—trade studies are required.
• There are many different composite materials—each with a unique set of attributes.
• There are many different composite processes. Each process has strengths and limitations for specific materials, shapes, performance, and production volumes.
• Composite design should not imitate both form and function of an existing design in another material.
• Take advantage of part consolidation wherever possible.
• Ensure composites will support any critical standards your products need to comply with.
• Tooling is generally hard to change once built—get it right the first time.
• Tooling is expensive for first article but can be used to manufacture many units. Cost per unit is low in volume production.
• Use composites to provide added value and competitive edge, and try to incorporate styling or features not previously possible.
Walinga is looking at using composites in its Animal Feed Discharge Auger—a trailer that delivers finished animal feed from a feed mill to a farmers bin using a steel auger system driven by hydraulic power.
• Durability and longevity. “Animal feed can be corrosive and abrasive. Abrasive products wear out primary metals such as steel and aluminum, albeit it’s more of a concern for aluminum than steel. Wear due to abrasion removes material and therefore affects the structural strength of the discharge auger.
• Corrosion resistance. “Steel discharge augers rust over time. Rust for many fleet owners is a huge appearance and image issue. For steel units, this can be overcome with processes such as galvanizing, but this adds more cost and weight.”
• Weight reduction. “Weight of a composites auger will be comparable to an aluminum version. A composites version would give much enhanced strength and abrasion resistance as compared to aluminum. The design can be done to put the strength where it is required—enhance the section modulus to make it comparable in strength to a steel version at a significant reduction in weight.”
“We are very new to composites and we don’t have a full understanding of what it takes to put a good composites project together,” he said. “So we’re looking at different types of material to make the best product with a targeted weight reduction. Right now, we’re looking at a very thin aluminum inner section with composites on the outside.
“The important things are to: think outside of the box; choose a project carefully; do your research and do it right; design for composites because they do not have the same protocols as the more traditional materials; partner with a reputable composites firm; and choose the right composites materials for your application. Composites might not be for you but you won’t know unless you carefully study it.”
New Trailer Product Development
David Mizgala, chief engineer
Innovative Trailer Design Industries Inc
Mizgala presented an analysis of high-strength and standard steels.
He said high-strength steels are defined as steels with yield strengths 80,000 psi, 100,000 psi (T1), and 130,000 psi. There are two types: high yield strength for web plate and flatbars for flanges; and high Brinnel, with impact tough AR300-AR500 that tends to be used on dumps.
Standard steels are defined as steels with yield strengths under 60,000 psi. They tend to be commercial grade steels 26,000 psi to 36,000 psi, and certified steels that have a certificate for 36W, 44W, 50W, and 60W.
Advantages of high-strength steels: higher strength-to-weight capacity; allow for greater payloads due to reduced tare weight; and desired lengths can be custom-ordered if sufficient tonnage is required.
Disadvantages: more costly per pound; primarily as quench and tempered; come from specialized mills; long lead times/rolling cycles; and different weld requirements.
Advantages of standard steels: lower cost per pound; hot-rolled with material certificates that can provide strengths greater than the minimum; readily available from most steel warehouses; and welding uses standard techniques.
Disadvantages: heavier sections required and therefore less payload capacity; limited selection of lengths depending on shape; flatbar and channels limited to 20- to 40-foot lengths; with structural beams, not all sizes are offered.
He offered some definitions:
• Maximum yield stress: The stress point at which a material will go from elastic deformation where it can return to its natural state to plastic (permanent) deformation.
• M=bending moment: The bending moment in a member is calculated by multiplying the force by the applied distance arm, its units are (in-lbf).
• z=section modulus: The geometric property for a given cross-section used in the design of beams or flexural members.
In designing for deflection, he said that in several cases, the strength of the section is sufficient to meet the load but the governing requirement may be the deflection. The Handbook of Steel Construction requires 1/300 of span for live loads, meaning that for every 300 inches, only one inch of deflection is allowed.
Mizgala said galvanizing has been used in the industry for many years for sub-components: door frames, landing gear bracing, bumpers, etc.
“The last 10 years has seen a large increase in hot dip galvanizing of entire trailer frames: chassis, converter dollies, B-trains, and flatbeds,” he said. “In most of your cases, it’s only in the last 10 years that full chassis have been converted into B-trains and full flatbeds have been galvanized.”
• Coating is bonded at the molecular level and forms a sacrificial layer. “So when galvanizing is scratched and exposed and rain or salts are trying to corrode the steel, it will take electrons from the steel but the steel itself will steal electrons from the zinc, so the zinc is sacrificing itself to protect the steel coating.”
• All internal sections are coated including hard-to-reach places.
• Zero maintenance. “This is more related to stationary items, but you don’t have to worry for 20 years. In our case with trailers, we’re somewhat less than that but it still has a lot of life.”
• The overall appearance remains relatively constant over the years.
• Modification of standard practices. “Drainage is required throughout. That includes tubes. If you have a tube that’s not aerated, the tube will explode, and usually the galvanizers will blow their own holes with a torch, so it’s best to build it into the process.”
• Distortion of the structure due to process. “On the door frames, because it’s a thin section, it can get distorted, so bracing in there is required.”
• Repair and modifications require additional procedures for health concerns.
• Grinding galvanized coating off prior to welding.
• Wearing appropriate filters for grinding and welding.
• American Galvanizers Association required for documentation.
• Inconsistency in the appearance over the unit. “If the chassis has a dull gray finish or spangled look, it basically comes down to steel chemistry. When you get a spangled look, that means the galvanizer adds a bit of tin to the bath to get the shiny look on it. So if somebody’s giving you a 100% zinc look, it will not have a shiny look.”
• Dependent on the steels chemistry.
• Dependent if tin is added to the zinc bath.
• Not all steels galvanize well. “The Sandelin curve provides a guide for mild steels. Anything under 0.04% on silicon or between .15% to .23% is the ideal area for galvanizing. It doesn’t mean that if it’s outside that it won’t galvanize, but you won’t get as nice a finish.
“You can get a crack in T1 (100 KSI) steel flange. Even though galvanizers say T1 steels galvanize with no problem, they do crack. On the top flange of a B-train, we had a scenario where we had a crack.”
He said galvanizing high-strength steels can be unpredictable. A crack can occur at the weld on the other side of the X-member because of weld stress concentration, pre- or post-heat, or a galvanizing recommended process not being followed.
He also discussed designs that involve more than a trailer. For example, he showed a photo of two halves of a trailer as used by Mosport International for a kitchen/serving Window.
“Different standards and codes may apply depending on the customer’s requirements and the permitting process the client will face,” he said.
Ontario/US /international building code defines wind/snow/load requirements, deflection and strength requirements; staircase and handrail standards; and occupancy limits and number of exits.
The Electrical Safety Authority (ESA) deals with electrical inspection and compliance and the Technical Standards & Safety Authority (TSSA) with gas and piping inspection and compliance.
In terms of engineering analysis, drawing packages that will be submitted to a city’s building department will require the following:
• Architectural package (O/A dimensions and layouts).
• Structural package (all members and joints detailed out).
• MEP package (mechanical/electrical/plumbing).
• Drawings are stamped by a professional engineer with a license in the jurisdiction that the drawings will be submitted in.
• In preparation of the package, a complete engineering analysis needs to be done.
• For a trailer, a 2D drawing is sufficient or possibly a 3D model from existing designed products.
• For a custom-designed product where the customer and you need to visual the space and determine if all the items requested will fit, a fully rendered scale model may be required.
“There are several software packages that can help create this visualization and rendering,” he said. “With the rendered product, any image can be taken and even an animation can be produced. If a customer likes what he sees, it usually goes to the tendering process. After the concept has been accepted, it is usually put out to tender to ensure that fair market value is obtained.”
Julien Nadeau, founder and CEO
Nadeau decided to start Alutrec in 1995 in Quebec, and it became the first aluminum flatbed trailer manufacturer in Canada. Nadeau, a former driver and fleet owner, said he is dedicated to better understanding the trucking industry.
Alutrec specializes in aluminum flatbed trailers and its latest product is a monocoque design, The Capacity, which he says is “the world’s lightest aluminum flatbed trailer.”
Monocoque is a French word for “single shell” or “single hull.” It describes early aircraft that had a fuselage with an outer skin that added strength to the inner frame. If some of the aluminum panels were removed, the fuselage would lose strength and its aerodynamic capabilities. Vans and reefers also have a monocoque design, with a body that’s strengthened by the sides, roof, and ends.
Nadeau theorized that a flatbed could be made to resemble a flattened tube that was similar to a fuselage. In a five-year project, he got validation from engineering departments at two nearby universities and partnered with aluminum research centers.
Nadeau’s monocoque flatbed has a floor formed from a stamped aluminum underskin featuring a series of flat, 9-inch extruded aluminum tubes with interior webbing. There are winch tracks and rub rails along each side. The underskin looks like a smooth boat hull.
The monocoque is so strong that it doesn’t need frame rails or crossmembers, which saves 2000 pounds of a conventional aluminum flatbed’s weight. So the tare weight starts at 6950 pounds for a two-axle version that’s 48 feet long by 102.3 inches wide.
A common Canadian configuration is a 53-footer with three axles, each sliding independently so spread can be adjusted to suit laws in various jurisdictions, and a third axle can slide out to make a tandem.
“Heavier loads and heights mean more revenues,” he said. “Improved aerodynamics means less fuel consumption. Authorization to run in all state and provincial jurisdictions in North America means less logistics and reduced equipment needs. The result? More profits.”
Nadeau says Alutrec’s extensive knowledge of aluminum technology allows it to make the most of the material’s strength and durability, while taking advantage of its characteristics.
Some of the key components:
• Alloy. “Not all flatbed trailer manufacturers use the same alloys. Alutrec makes the most of each type of alloy to ensure your aluminum flatbed trailer is as strong as possible.”
• Beams. “Alutrec beams are designed to use two large aluminum extrusions assembled by using high pressure riveting (huck-bolt). Our manufacturing process ensures no broken rivets, weakened structures or loose nuts that could cause excessive torsion.”
• Cross members. “Our cross members are designed to work in collaboration with our exclusive interlocking floor, allowing cross members to be spaced apart. This result is a lighter flatbed trailer with strong structural rigidity.”
• The floor. “The aluminum extrusion floor has all four sides closed and tampered to offer outstanding strength. These extrusions transfer a large portion of the load to the main beam since they are ‘locked’ together. This means less pressure on the rest of the structure, allowing it to last longer. Additionally, the floor pieces are interlocked throughout the entire length of the flatbed trailer, which means the trailer remains straight—even when making the tightest turns. This result is better stability on the road.
• Assembly process. “Aluminum is a material with many unique characteristics and to make the most it, you must understand its properties and take advantage of them. We ensure that each step of the process—from perforation, welding, folding and mechanical assembly—respects the properties and behaviors of aluminum, maximizing its potential.”
• Corrosion protection. “Aluminum reacts chemically when in contact with steel. Therefore it is important to avoid contact between these types of material. To accomplish this process, we use a high-density membrane which offers protection against tearing and humidity, increasing longevity.
Miles Jorgenson, engineer supervisor
Jorgenson said the company, which was founded in 1948, built a grain trailer in 1972 for its first customer in the transportation industry, Andy’s Transport.
“This has been the core of the company,” he said. “We’re surrounded by farmland, and agriculture drives a lot of industry in Saskatchewan.”
The company also serves commercial, oil and gas, forestry, and gravel industries, The primary product is the O/E Steel Super B Grain Bulker, and the company moved to galvanized trailers three years ago.
“We tend to be a customer-driven company,” Jorgenson said. “We have production runs of one, meaning every trailer has its own specifications. Every customer has the ability to choose custom features. We strive to be the strongest and longest. Composite is a new challenge for us. We have to maintain high quality because if we don’t, it costs us on the other end. We all recognize high resale value, which is a testament to the quality. We rely heavily on component suppliers to maintain features.”
The Legacy Aluminum Bulker has been released to help meet the demand of grain on farms that has to be delivered.
“One of the challenges with grain movement is contamination,” he said. “We want to eliminate product from contacting paint. The customer wants clean product. This is food we’re delivering. It’s been determined that any amount of contamination could give a potential customer an excuse to reject it. There are lots of places contamination can come from, and we don’t want to be one of them. An aluminum body gives us that ability.
“We try to eliminate as many nooks and crannies and hidden spots where corrosion can take hold. Smooth surfaces are one of our objectives. And we have to remember structural design. These trailers have vulnerability because the grain storage compartment is part of the structure of trailer.”
He said Finite Element Analysis (FEA) is a key part of the process.
“We rely on a few tried-and-true methods to verify that our trailers are going to stand up to whatever customers do,” he said. “One of the problems with FEA is establishing legitimate inputs. What is that trailer actually going to experience? It’s easy enough to figure out what the payload’s going to be. We know what the highway allows us to carry, so we can put the loads in. Then you have all the dynamics. Customers are driving these things through ditches or soft ground. We like to develop physical tests as another avenue of establishing longevity in the trailer.
“Can we rely on FEA results alone? We think they should be supplemented with other testing.”
• Field test. “We will hand it off to a customer and let them take it through the paces. That’s valuable for verifying we did the right testing and also the marketing value. We know it’s going to stand up.”
• Terrain compliance. “These trailers more and more often are being used right from the farm all the way to grain terminals, so they see a lot of highway as well as off-road. They’re delivering at ramps at loading facilities. There is a lot of uneven terrain.”
• Component “racking” test. “We take component and design fixtures specifically for that component. What stresses do we expect that component to have to withstand? Once we’ve tested components, we can test the entire trailer with a whole trailer “racking” test. A trailer is twisted from front to back and side to side. We’re trying to simulate three to five years of field service. It helps us identify weaknesses and places on the trailer that are more vulnerable.”
• Moisture protection. “With hauling grain, it also has to be waterproof. Any moisture that enters the grain compartment will deteriorate and rot. So it’s very important we have moisture tightness.”
New Developments in Trailer Products
Tony Nathan, sales engineer
K-Line Trailers Ltd
Nathan said K-Line has a diverse product spectrum and a less diverse geographical market.
“We are a custom trailer manufacturer, and that’s a grossly overused word,” he said.
“We can’t agree on what to call a low-deck, heavy payload trailer. If you get an Alberta-based manufacturer talking to an Ontario-based manufacturer, floats are completely different trailers.
“The lowbeds that we make start at 40,000 and 50,000 kilos of payload. Lowbeds become Heavy Haul become Super Haul, where you’re almost making your own regulations in negotiating with various authorities and jurisdictions. You’re off the book. Most jurisdictions will stop somewhere around 85,000 to 120,000 kilos gross. When that’s your payload, they don’t have a set of rules. There’s no clear threshold.”
He said when a customer is trying to expand to new territory geographically, it can be a difficult situation.
“It may be that the way it’s done in your home province is different than in a neighboring province,” he said. “It may be that because they’re going from a 50-ton trailer to a 35-ton step deck and now they’re moving into a lowboy or float, you’re moving into a different kind of regulation,” he said. “You’re no longer dealing with the Commercial Transport Guide, which is widely published and online. You’re moving into policy. You need to obtain a permit and that permit has restrictions. ‘I’m trying to move 65 tons through your province. How would I do that?’
“The policy is not always online. You have to drive the Permit Office process backwards. There is different equipment. So we have four-axle trailers not allowed in BC or Saskatchewan or Manitoba, but Alberta and Quebec do allow them.”
He said that trailer manufacturers need to work together.
“It’s not just you telling them how to do it or them telling you how to do it,” he said. “You’re working together on it.”
“We’re working with customers who are going to ask, ‘How much would it change the weight if I … ?’ Or, ‘Will the operation of the trailer change if I …?’ Their questions are quick to be asked, but can take weeks in engineering to answer.
“You can choose to make a really easy-to-use product that’s very complicated or do it the other way around and make it a difficult-to-use product that’s very simple. It depends on what your customer is looking for. The multi-extendible/trombones where the deck pulls out of a deck can pose structural challenges. Your shims wear as things age.
“Trailer manufacturers tend to design for moving payload. In the case of mining equipment, you have to design to get to the job site. We will spend tens of thousands of dollars to compartmentalize shipping containers to a mine.”
He said road trains that are running in the Northwest Territories brings major challenges.
“It has to be able to operate in extreme climate conditions,” he said. “One combo is in excess of 182 feet long, weighs three-quarters of a million pounds, and is over 1100 horsepower. In order to transport this to a mine site, each trailer splits down and it travels by ice road. So when a customer tells you they absolutely have to have product delivered by March 1, what happens if we’re a week or two late? The ice road melts and we can’t move product in until the next winter. So if you’re two weeks late, you might as well be 50 weeks late.
“In this case, we worked with the Ministry of Transport. You start working with the mines inspector. Mines have a phenomenal safety culture. You’re operating in extreme climates. They have two or three months of decent weather. It’s minus-40 six months out of the year. It runs on consecutive 12-hour shifts. It has no down time. It has scheduled maintenance time, but if something breaks down, time is the absolute killer at a mine. They will stock tires and transmissions to avoid down time. There are no parts stores around the corner you can run to.” ♦