MARCO Mining Services Uses ALGOR FEA Software to Investigate Chilean Mining Accident

	For MARCO’s Chilean mining client, the 2500-horsepower, 800,000-pound hauling trucks are essential tools for transporting raw materials from the mines to the processing plant.
	The rear-axle housing of the mining truck contains the motors for independent wheel motion and supports the weight of the vehicle, including its payload.
	When he arrived on the scene of the truck accident, Rene Suazo of MARCO found the right rear-axle housing completely severed from the mining truck. The main point of stress appeared to be the area around the padeye, the point at which the rear housing connects to the hydraulic shocks and the forward  part  of the vehicle.

MARCO Mining Services Ltda. of Iquique, Chile, an affiliate of Marine Construction and Design Company of Seattle, Washington, has been a permanent fixture in northern Chile’s mining industry since copper mining resumed there in the mid-1990s. MARCO provides engineering, analysis, design and manufacturing support to meet the specific requirements of mining operations, including equipment manufacture and infrastructure construction. When approached by one of the major mines in northern Chile to investigate the cause of a failure in the rear-axle housing of a mining truck, MARCO Structural Engineer Rene Suazo was named the project head in charge of damage inspection, analysis and reporting. With the help of ALGOR FEA, Suazo located the source of the problem and recommended design enhancements. His use of ALGOR spared the client future injuries to drivers and saved down time and repair costs, while avoiding the enormous costs of a new truck fleet.

Mining Truck Failure

MARCO’s mining client uses 2500-horsepower, 800,000-pound trucks with a payload capacity of 260 metric tons to transport raw, mined copper materials to process plants. Because these trucks do not have chassis, axle housings provide support for the wheels and payloads while electric motors within the axle housings drive the wheels for independent motion.

When Suazo arrived on the accident scene, he saw that the axle housing on the damaged vehicle had fractured completely, causing the right-hand wheel motor to separate from the truck. The driver was injured and the truck rendered useless. The mining company had never experienced this type of failure before.

Obviously, given a major structural failure to a key component, MARCO’s client could not simply operate its fleet of trucks as usual. But without the use of its hauling trucks, the mining process would come to an abrupt halt. The potential shut-down of the company’s truck fleet would add up to enormous losses. MARCO’s role in analyzing and recommending repairs was vital and time-critical.

Modeling and Analyzing the Axle Housing

With dimensioned drawings and mechanical specifications of the axle housing from the manufacturer and confirmation of the dimensions through his own measurements of the damaged part, Suazo began to model the axle housing. As specified by the manufacturer, he defined the steel as ASTM A-572, grade 50. He made sketches of the model in SolidWorks and used ALGOR's InCAD technology for direct CAD/CAE data exchange to mesh the model in ALGOR.

He created the finite element mesh with refinements at critical points, particularly at areas near the padeye, the point at which the rear housing connects to the hydraulic shocks and the forward part of the vehicle. This same area is where failure had been visually identified on the part. 

Given that the model properties were held stable due to the known composition of the part, the only remaining unfixed variables were the loads on the model. Suazo’s objective was to discover what kinds of conditions might cause failure. He performed linear static stress analyses using various load cases supplied by the manufacturer, as well as the mining operation, who was consulted for known operational loads.

Suazo found that when a torsional load case was applied, stresses were critically high in the exact area of the model where damage had occurred in the axle housing. By comparing the FEA software results with his visual inspection of the damaged part, he was able to conclude that such a torsional load had been the cause of the axle housing failure.

MARCO reported its findings, making recommendations for minimizing torsional loads by adjusting the truck suspension in consideration of road conditions. Following this report, MARCO was contracted to make a general inspection of the customer’s entire fleet of mining trucks. “ALGOR was the essential tool that helped us to obtain this contract,” said Suazo.

Preventative repairs were applied to one truck at a time, allowing the mine to continue its operations. Since enacting MARCO’s recommendations, no further accidents have been reported. “Our customers are very happy. We not only made repairs to their trucks, but we also made recommendations for the structural improvement of their vehicles to prevent future accidents and ensure safe operations,” said Suazo.

Future Plans

Given the successful application of ALGOR for their mining client, MARCO plans to continue using the software for future applications. “I initially chose ALGOR based on a cost-benefit analysis in comparison with similar products,” said Suazo. “Thanks to the excellent technical support, a great relationship with my service team and a fast and easy learning curve, we will continue to use ALGOR. Today, I am even more convinced that ALGOR was the right choice.”

Rene Suazo has been a naval engineer with MARCO Chilena Ltda. in Iquique, Chile for 11 years. He earned an Engineering degree at the Universidad Austral in Chile.

Suazo created a CAD model of the rear-axle housing in SolidWorks and captured it seamlessly in ALGOR for meshing and analysis.

Analysis of torsional loads in ALGOR showed that the area around the padeye was subject to critical stresses, validating the visual inspection of the damaged part.

Rene Suazo, Structural Engineer at MARCO, used ALGOR FEA software to analyze the rear-axle housing of a mining truck damaged during use in one of the major mines in northern Chile.