Category: Systems & Machine Design

 

 

While you are dangling in the air, staring straight down at the pavement 60 feet below (getting closer every second), it is not the time to worry whether the ride you are strapped into is safe. However, it is a legitimate concern—one that most likely more people have had since the Fireball tragedy at the Ohio State Fair in 2017.

After all, so many of these rides roll into town, are set up, taken down, and roll out again before you can finish your cotton candy. One can’t help but wonder: “Can these rides possibly be safe? Are they soundly constructed? Is anyone making sure they are up to code?” Rest assured that the answer to all of these questions is “Yes.” MJ Engineering uses its years of experience to help make sure of it. We have been working on amusement park rides for about 10 years, advising on ride repair procedures, performing failure analyses, safety and risk assessments, and code compliance testing, plus helping with ground-up designs.

MJ Engineering’s client A.R.M. (USA) Inc. put the finishing touches on the second evolution of its popular pendulum-style thrill ride, Frenzy, which MJ Engineering has been involved with from its conception. The new Frenzy was unveiled in November 2018 at the International Association of Amusement Parks and Attractions (IAAPA) Expo in Orlando, FL to screams of enthusiasm from riders as they got above 90 degrees from vertical.

“Hundreds of hours of engineering go into these rides,” says MJ Engineering President, Richard Wand.

In fact, amusement manufacturers must meet a federal code that is hundreds of pages long for amusement park rides, taking into account everything from patron (rider) safety, ride dynamics, storage, transport, and anything that could possibly affect the ride related to its structure, controls, performance, life, or environmental conditions like wind and ice.

Shripal Bhavsar, of MJ Engineering, helped to certify Frenzy. “Our process is to do the analysis and calculations for each individual part of the ride, based on the codes that are available,” says Bhavsar. “We usually determine a factor of safety, depending on what part we are looking at, which is critical to the structure and the patrons.”

To verify ride strength, MJ Engineering uses a combination of hand calculations and finite element analysis (FEA), which is a computerized method to help predict how the ride will react to real-world forces to determine whether it will break, wear out, or work the way it was designed. “In a nutshell,” says MJ Engineering’s Phil Snyder, who worked on both versions of Frenzy, “it needs to be designed to sound engineering principles.” Safety is one of those principles.

“Safety is extremely important to us,” says Wand, “And if we think that the safety of the patron has been compromised in some fashion, we’re required—we’re bound—to say something and shut that ride down.” For that reason, states should have more professional engineers involved in the inspection and approval process of these rides. Ultimately, it is the manufacturer’s responsibility. However, MJ Engineering supports the manufacturer by providing our professional opinion on what they should do.

“The Amusement industry is held to very high standards—manufacturers understand this better than anyone,” says Mike Gill, of A.R.M. “Generally, we approach MJ Engineering with a task, whether it be a conceptual design, a design change of an existing ride, or a repair. Then we collaborate on the task until it meets all requirements.”

For example, A.R.M. asked MJ Engineering to help the new Frenzy lose some weight to make it easier to transport and build. The challenge was controlling the dynamics of Frenzy, which is a big pendulum that swings riders back and forth. MJ Engineering managed to figure out how to reduce Frenzy’s weight while securely keeping all four feet on the ground at all times.

To achieve a higher level of safety, we spend a lot of time doing “failure mode analyses,” which means looking at everything that could possibly go wrong with a ride. We assign a risk assessment to it, and if it turns out to be high, we will put other steps in place to make sure it is mitigated, and the risk is even further reduced. Most of the time, we are looking at stresses in the structural members, specifically fatigue.

Generally, amusement park rides are very dynamic in the way they move, not just during every ride cycle, but as the ride moves, due to changes in the loads and stresses, which affect the structure. For example, the left side of the ride might be heavily loaded, and then the right side might be heavily loaded as the ride moves, due to centrifugal and dynamic forces. This situation leads us to look at fatigue, which examines the number of cycles of load changes a ride has. We determine what the minimum and maximum load cases are, then we look at the number of times it fluctuates between them, which enables us to calculate a fatigue life and predict when that metal is going to fail.

According to Federal code, amusement park manufacturers are required to make rides last 35,000 working hours, which equates to approximately 20 years. Federal guidelines also dictate patron loads and how the restraints must be designed, based on the dynamics of the ride. Fortunately, patron load can usually be determined by seat fit and what the restraint will do, which saves patrons the embarrassment of being weighed as they are standing in line. The general rule is if the restraint locks, you can ride.

We also look at the ergonomics of seat fit and the patron restraint, such as the shoulder harness or lap bar, and the adjustability of it, to make sure we capture the patron as easily as we can while still keeping them safe. Restraint design also depends on the dynamics of the ride, how many inversions it has, and how harsh those inversions are. When we design the harness, we try to take into account how much force the patron could physically exert, plus the patron’s body weight, to make sure the harness is going to stay where it is. We spend much time making sure the restraint is capable of doing its job.

We do get to engineer fun, too. You know that stomach-drop feeling? A lot of it has to do with g-forces. Most of the time, the manufacturer who is designing the ride describes to us the experience they want riders to have, and we then assist them with achieving it—within limits (back to our safety standards). For example, if we’re applying a lateral g-force and a down g-force, there are limits on how long the patron can be exposed to that feeling—and staying within the limits of safety is always MJ Engineering’s and A.R.M.’s number one goal.
At the end of the day, we want to make sure that Frenzy or any other amusement ride we design or analyze gives its riders the thrill they are seeking while keeping them safe and returning year after year.

We also look at the ergonomics of seat fit and the patron restraint, such as the shoulder harness or lap bar, and the adjustability of it, to make sure we capture the patron as easily as we can while still keeping them safe. Restraint design also depends on the dynamics of the ride, how many inversions it has, and how harsh those inversions are. When we design the harness, we try to take into account how much force the patron could physically exert, plus the patron’s body weight, to make sure the harness is going to stay where it is. We spend much time making sure the restraint is capable of doing its job.

We do get to engineer fun, too. You know that stomach-drop feeling? A lot of it has to do with g-forces. Most of the time, the manufacturer who is designing the ride describes to us the experience they want riders to have, and we then assist them with achieving it—within limits (back to our safety standards). For example, if we’re applying a lateral g-force and a down g-force, there are limits on how long the patron can be exposed to that feeling—and staying within the limits of safety is always MJ Engineering’s and A.R.M.’s number one goal.
At the end of the day, we want to make sure that Frenzy or any other amusement ride we design or analyze gives its riders the thrill they are seeking while keeping them safe and returning year after year.

“The Amusement industry is held to very high standards—manufacturers understand this better than anyone,” says Mike Gill, of A.R.M. “Generally, we approach MJ Engineering with a task, whether it be a conceptual design, a design change of an existing ride, or a repair. Then we collaborate on the task until it meets all requirements.”

For example, A.R.M. asked MJ Engineering to help the new Frenzy lose some weight to make it easier to transport and build. The challenge was controlling the dynamics of Frenzy, which is a big pendulum that swings riders back and forth. MJ Engineering managed to figure out how to reduce Frenzy’s weight while securely keeping all four feet on the ground at all times.

To achieve a higher level of safety, we spend a lot of time doing “failure mode analyses,” which means looking at everything that could possibly go wrong with a ride. We assign a risk assessment to it, and if it turns out to be high, we will put other steps in place to make sure it is mitigated, and the risk is even further reduced. Most of the time, we are looking at stresses in the structural members, specifically fatigue.

Generally, amusement park rides are very dynamic in the way they move, not just during every ride cycle, but as the ride moves, due to changes in the loads and stresses, which affect the structure. For example, the left side of the ride might be heavily loaded, and then the right side might be heavily loaded as the ride moves, due to centrifugal and dynamic forces. This situation leads us to look at fatigue, which examines the number of cycles of load changes a ride has. We determine what the minimum and maximum load cases are, then we look at the number of times it fluctuates between them, which enables us to calculate a fatigue life and predict when that metal is going to fail.

According to Federal code, amusement park manufacturers are required to make rides last 35,000 working hours, which equates to approximately 20 years. Federal guidelines also dictate patron loads and how the restraints must be designed, based on the dynamics of the ride. Fortunately, patron load can usually be determined by seat fit and what the restraint will do, which saves patrons the embarrassment of being weighed as they are standing in line. The general rule is if the restraint locks, you can ride.
We also look at the ergonomics of seat fit and the patron restraint, such as the shoulder harness or lap bar, and the adjustability of it, to make sure we capture the patron as easily as we can while still keeping them safe. Restraint design also depends on the dynamics of the ride, how many inversions it has, and how harsh those inversions are. When we design the harness, we try to take into account how much force the patron could physically exert, plus the patron’s body weight, to make sure the harness is going to stay where it is. We spend much time making sure the restraint is capable of doing its job.

We do get to engineer fun, too. You know that stomach-drop feeling? A lot of it has to do with g-forces. Most of the time, the manufacturer who is designing the ride describes to us the experience they want riders to have, and we then assist them with achieving it—within limits (back to our safety standards). For example, if we’re applying a lateral g-force and a down g-force, there are limits on how long the patron can be exposed to that feeling—and staying within the limits of safety is always MJ Engineering’s and A.R.M.’s number one goal.
At the end of the day, we want to make sure that Frenzy or any other amusement ride we design or analyze gives its riders the thrill they are seeking while keeping them safe and returning year after year.

Click here to see an edited version of this article on the Amusement Today amusement industry news website.