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It is common that angular velocities can be different from time to time between an engine output and transmission input, because both are connected by a damper in torque converter with flexible elements in it. When this difference occurs abruptly for some reasons, an internal impact could start between the engine-attached members (also known as driving members) and the transmission-attached members (or driven members). The resulting impact load could be several times the torque an engine’s combustion force can generate, depending on the impact energy. An impact load can be very devastating to a torque converter and other power-train members, just as to all other mechanical systems. This work presents a comprehensive and interesting study to help understand the rotational impact behavior for a system where none of bodies is stationary at the onset of impact.

Determining an amount of clutch clearance for the lockup device in a torque converter is important for its being operating precisely in the intended mode. Challenges may exist for the torque converters whose nominal clearances are on purpose very small. Any potential changes in the clutch lockup system (e.g., due to the deformation of components) may make such a small clearance instantaneously diminish during the mode of open-clutch, thus leading to unwanted drag in the clutch and unnecessary loss of energy. In the open-clutch mode, the actual clutch clearance may be different from the nominal clearance anticipated, primarily because of deformation caused by the internal load acting on clutch members. It has been found that the pressure distribution in a clutch chamber also depends on the very clutch gap through which the fluid flows. This interdependence between the fluid pressure load and structural deformation is typical of two-way coupling in simulation.

Considered in this study by the use of finite element model is a unit of assembled stator and one-way clutch (OWC) housed in a test setup, where the inner chamber is maintained at a given elevated temperature while its exterior housing surfaces are exposed to the room temperature. The two key components of dissimilar metals are assembled through the conventional interference fitting at their interface surfaces to form a friction joint at the room temperature. Due to the difference in the thermal expansion coefficients of two dissimilar materials, the outer component of aluminum from this joint tends to expand more than the inner component of steel when the temperature rises, thus leading to a possible relaxation in joining connection at their interface.

Engineers have been interested in a thorough understanding of how a case-hardened part, consisting of soft substrate (or core) and hard surface, behaves under various types of loads, ranging from extremely destructive load to mild cyclic loads. The use of numeric simulation, such as well known finite element method, has made it much easier to achieve this. Throughout this investigation, the author proposes a methodology to treat such a case-hardened part as multi-laminated metal with a relative thin outer layer whose ultimate tensile strength may be several times as high as its inside core material. In the case studies to demonstrate the technique, a representative automotive component is subject to various loads due to not only the inertia of its own but also that imparted from heavy springs housed within it. A comparison was made between two approaches to account for the hardness transition between the hard layer and soft core.

Metal fatigue has been a topic interesting to engineers for long, because it has had a profound impact on making the design of virtually all products more reliable. As the research in this area evolved, the understanding of fatigue has been gained so tremendously that it has been become possible to conduct more and more complicated fatigue analysis or simulation without having to undergo lengthy fatigue tests for a product under design. In this work is a numerical model to predict the fatigue life of a power train component, whose metal material essentially behaves as being inhomogeneous due to a thin and hard surface layer on the top of the base material. As a typical case in the power train of automobiles, the clutch component is subject to the inertial load arising from an angular velocity as well as the torque loads, varying cyclically with time in a form other than what is called constant-amplitude.

As the demand for various electric vehicles (EV) grows, it has become important to understand and assess the mechanical characteristics of the enclosure (also known as case, housing, etc.) that houses heavy battery modules. As a battery enclosure is usually mounted to the body of a vehicle, there is no doubt that it will be routinely subject to the vibration excitation imparted by uneven road surfaces the vehicle is traveling on. The nature of unevenness can vary in any possible ways and, therefore, the load to excite the vibration on the enclosure is commonly treated in a non-deterministic or random fashion. In this work, the available technique for handling a typical random excitation of acceleration will be applied to a linear system of battery enclosure used in a popular EV on the market.

An ability to design automotive systems with optimum parameters has become very crucial in the competitive industry. Today, there are many shape optimization algorithms to choose, depending on the nature of the design parameters. Compared with the topology optimization, a topography optimization can be a good alternative. Because of the less number of design variables required for the same optimization model, the topography optimization process is generally faster. In this study, an assembly consisting of several identical sheet metal components is employed for demonstrating the effectiveness of topography optimization, in which various beads are to be derived with appropriate heights and widths, where needed, at the discretion of the algorithm to attempt to render the design variables within the constraints. The identical pieces are arranged around an axis of revolution such that the geometric shape is cyclic symmetric at a constant angular spacing.

Using rivets to join the metal parts has always been commonplace, not only in aerospace but also in automotive industries. In order to have a rivet joint work properly upon assembly, It is a common practice that the rivet shank has to be radially expanded and fit tightly with the holes of the jointed components, under a great amount of pressing loads on it. When the stiffness around these holes is insufficient due probably to the design limitation, the deformation may be severe enough to induce high stresses on them. It is very beneficial to use numeric methods to simulate the riveting process and predict whether a rivet joint will be sustainable in the manufacturing process. In this work, analyzed is a specific type of riveted assembly in which its rivet hole is at the close proximity to the edge of plate. In addition, the material characteristics for the riveted plates with case hardening are accounted for by modeling them as bi-layered structures.

Presented here is the finite element modeling of plate-structures within which mechanical properties varied dramatically from their outer surfaces towards inside cores. Developing such a model representing what can be characterized as laminates is of great significance in accurately predicting the strength. The benefits of this proposed methodology will be discussed by case studies of a centrifugal pendulum that has gained its popularity in high-end passenger cars because of its superior vibration suppression. The system in this work is subject to an excessive and destructive load due to centrifugal forces at extremely high angular velocities. It can be shown that the inner core, with much softer mechanical properties, easily gets into the plastic state and significantly restrains it from continuing to carry more loads as the angular velocity is ramped up. Consequently, the outer layers have to take an increased share of loads and their stresses are significantly raised.

Vibration from a mechanical system not only produces unwanted noises annoying to people around, but also runs a risk of fatigue failure that would actually hinder its functionality. There are several forms of vibration depending on the sources of excitation forms. Mechanical systems with rotating components can be subjected to sinusoidal excitation due to the fact the center of mass is not perfectly aligned with the rotating axis. If the rotating speed is strictly ramping up or ramping down, this can create an excitation whose frequency is changing with time in a frequency range corresponding to the speeds swept. Compared with a single sinusoidal excitation, the issue with fatigue at swept sinusoidal excitation, is that as it sweeps through a wide frequency range, some swept frequencies will definitely coincide with the natural frequencies of the system. Certainly, the stress response exactly at the resonant frequency becomes the highest and could account for a lot of fatigue damage.