Browse Topic: Fatigue
Durability validation of full vehicle structures is crucial to ensure long-term performance and structural integrity under real-world loading conditions. Physical test strain and finite element (FE) strain correlation is vital for accurate fatigue damage predictions. During torture track testing of the prototype vehicle, wheel center loads were measured using wheel force transducers (WFTs). In same prototype strain time histories were recorded at critical structural locations using strain gauges. Preliminary FE analysis was carried out to find out critical stress locations, which provided the basis for placement of strain gauges. Measured loads at wheel centers were then used in Multi Body Dynamics (MBD) simulations to calculate the loads at all suspension mount points on BIW. Using the loads at hard points transient analyses were performed to find out structural stress response. Strain outputs from the FE model were compared with physical measurements. Insights gained from these
In heavy-duty tippers, where challenging conditions demand high torque, planet carriers play a crucial role by enabling efficient load distribution and torque transmission while supporting gear ratio and speed variation in space-constrained systems such as automatic transmissions, hybrid drivetrains, and electric vehicles. This paper focuses on the comprehensive durability performance assessment of planet carrier housing (PCH) using duty cycles derived from road load data acquisition (RLDA) measurements for a heavy-duty tipper gearbox development program. The existing Design Validation Plan (DVP) for the planet carrier considers first gear utilization of 10-15% at 40% vehicle overload, in line with historical data. However, recent trends in mining applications revealed vehicle overloads of 55-65%, leading to an increase in first gear utilization (25-35%). This shift presents challenges for original equipment manufacturer (OEM) to enhance design durability while incorporating additional
The smart industrial revolution in any organization brings faster product delivery to the market, which can meet customer expectations and full life requirements without failure. Failure per machine (FPM) is a very critical metric for any organization considering warranty cost and customer perception. One such area which needs a detailed evaluation is bolted joints. Bolts play a pivotal role when integrating a subassembly with the main structure. Often, it is challenging to address bolt failure issues due to vibration induced in structures. Current bolt virtual evaluation methods help to evaluate bolts in simple loading conditions such as axial and bending loads. But it is quite complicated to evaluate the bolts which are prone to vibration loading. Traditional methods of using gravity loads miss out on dynamic characteristics, hence it must be simulated using modal dynamic analysis. With the current vADV (virtual accelerated design verification) method it is not possible to capture
Puddling is a crucial process in rice cultivation, involving the preparation of the soil in a flooded field to create a soft, muddy seedbed. There are two classifications for puddling: full cage and half cage. Full cage puddling involves replacing the rear wheels of the tractor with steel paddle wheels, which are used to till the rice paddies directly without any additional implement. In the half cage puddling, the rear wheels remain on the tractor, and a smaller cage or paddle wheel is attached to the outside. Considering the field size, the operator often releases the clutch very quickly after a speed or direction change. This generates torque spikes, which are harmful to Transmission Gears and Clutches. This can lead to gear teeth bending fatigue failure due to repeated higher bending stresses. In this paper, a study related to how to reduce overall product development time by simulating bending fatigue failure of gear in lab environment is presented. A systematic approach is used
The first step in designing or analyzing any structure is to understand “right” set of loads. Typically, off-road vehicles have many access doors for service or getting into cab etc. Design of these doors and their latches involve a knowledge of the loads arising when the door is shut which usually involves an impact of varying magnitudes. In scenarios of these impact events, where there is sudden change of velocity within few milliseconds, produces high magnitude of loads on structures. One common way of estimating these loads using hand calculations involves evaluating the rate-of-change-of-momentum. However, this calculation needs “duration of impact”, and it is seldom known/difficult to estimate. Failing to capture duration of impact event will change load magnitudes drastically, e.g. load gets doubled if time-of-impact gets reduced from 0.2 to 0.1 seconds and subsequently fatigue life of the components in “Door-closing-event” gets reduce by ~7 times. For these problems, structures
The usage of additively manufactured (AM) notched components for fatigue-critical applications presents non-trivial challenges, such as the ubiquitous presence of volumetric defects in AM parts. Volumetric defects accelerate fatigue crack nucleation, impact short crack growth, and are near-impossible to fully eliminate. This study investigated the synergistic effects of volumetric defects and notch geometry on the fatigue behavior of L-PBF AlSi10Mg and 17-4 PH SS notched specimens. The criticality of the defects on fatigue behavior is investigated using a non-destructive evaluation technique. A classical linear elastic fracture mechanics (LEFM) approach was modified and used to quantify the effects of several factors including notch geometry, defects’ size, and location, on the fatigue crack initiation behavior. The modified LEFM approach utilized X-ray computed tomography data and linear elastic finite element analysis of local stresses in different notch geometries; to calculate and
The continuous improvement of validation methodologies for mobility industry components is essential to ensure vehicle quality, safety, and performance. In the context of mechanical suspensions, leaf springs play a crucial role in vehicle dynamics, comfort, and durability. Material validation is based on steel production data, complemented by laboratory analyses such as tensile testing, hardness measurements, metallography, and residual stress analysis, ensuring that mechanical properties meet fatigue resistance requirements and expected durability. For performance evaluation, fatigue tests are conducted under vertical loads, with the possibility of including "windup" simulations when necessary. To enhance correlation accuracy, original suspension components are used during testing, allowing for a more precise validation of the entire system. Additionally, dynamic stiffness measurements provide valuable input for vehicle dynamics and suspension geometry analysis software, aiding in
Innovators at the NASA Glenn Research Center have developed a toughened hybrid reinforcement material made from carbon fiber and carbon nanotube (CNT) yarn for use in polymer matrix composites (PMCs). The new material improves toughness and damping properties of PMCs, enhancing impact resistance, fatigue life, as well as structural longevity.
Researchers developed wearable skin sensors that can detect what’s in a person’s sweat. Using the sensors, monitoring perspiration could bypass the need for more invasive procedures like blood draws and provide real-time updates on health problems such as dehydration or fatigue. The sensor design can be rapidly manufactured using a roll-to-roll processing technique that essentially prints the sensors onto a sheet of plastic.
Engineers can now capture and predict the strength of metallic materials subjected to cycling loading, or fatigue strength, in a matter of hours, not the months or years it takes using current methods. In a new study, researchers from the University of Illinois Urbana-Champaign reported that automated high-resolution electron imaging can capture the nanoscale deformation events that lead to metal failure and breakage at the origin of metal failure.
This specification defines the procedures and requirements for joining metals and alloys using the electron-beam welding process.
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