Fatigue Damage Degree Evaluation of C-SMC Using Thermoelastic Temperature Variations

Atsushi Akai (Toyota Central R&D Labs., Inc. (Present Affiliation: Kyoto University of Education))･Yasumoto Sato (Toyota Central R&D Labs.)･Yukihiro Hamada･Atsushi Mikuni (Toyota Motor)

Recently, C-SMC—a discontinuous carbon fiber-reinforced plastic produced via sheet molding compound methods—has attracted significant interest in the automotive industry owing to its reasonable balance between the mechanical properties and production efficiency. A reliable technique for evaluating the fatigue damage of C-SMC is required to guarantee its long-term use. In this study, a technique for assessing the fatigue damage degree of C-SMC using the non-dimensional thermoelastic temperature amplitude is proposed, and its effectiveness is investigated.

Effects of Tension and Bending Loads on the Fatigue Threshold in a Stainless Steel Sheet (Part 2)
-Changes due to Stress Ratio-

Gyoko Oh･Atsushi Umezawa (Tokyo Roki)

In this study, we proposed a method to predict the change in the threshold stress intensity range ∆Kth by quantifying the effect of stress ratio using the strength factor of a Walker-type function for fatigue fracture in mode I under tension load and in mode IIII under plane bending load. The effect of the crack front shape was taken into account, as well as the plastic zone size at the crack tip. We also presented a prediction model for the effective stress intensity range that takes into account the plasticity-induced crack closure effect associated with the plastic strain hardening effect.

Fatigue Life Prediction Method for Point Joints Considering Multiple Fracture Modes
-Fatigue Life Prediction Method for Flow Drilling Screw (FDS) joints-

Hiroaki Kawamura･Eita Niisato･Suguru Goto･Kazushi Urakawa･Sogo Takuno･Toshiyuki Isono (Toyota Motor)

This paper describes a fatigue prediction method for the point-based joints in car bodies. There are two directions of fatigue crack propagation, the sheet thickness direction and the interpolate direction, for the fatigue fracture of point fasteners. It is essential for accurate fatigue life prediction to consider the crack propagation direction using numerical simulations. Previous papers proposed simplified joint models for vehicle bodies’ fatigue life prediction that assumed a specific fracture mode. It took a lot of work to simultaneously estimate multiple fracture modes using a particular model. Therefore, they needed to use various models properly or to consider complicated parameter combinations. This paper proposes a fatigue life prediction method considering multiple fracture modes simultaneously. A simplified model representation method is introduced for Flow Drilling Screw joints.

Numerical simulation for lap joints considering adhesion

Hirofumi Sugiyama･Tomoki Nomura･Shigenobu Okazawa (University of Yamanashi)

This paper proposes a numerical simulation method that considers the adhesion region using a damage model and numerical techniques for multi-material structures. The damage model is based on continuous damage mechanics and can deal with the softening behavior of the adhesion region. Furthermore, numerical techniques express the crack path explicitly. Finally, the representative numerical example shows that the novel method is verified.

CAE Analyses for Rotary Friction Welding of the Dissimilar Metal Pipes with Closed Forging Method
-Adjustment Analyses for Exploring Construction Conditions of RFW Bonding of the Pipes with MBD Method-

Tomohiko Ariyoshi (Atori CAE)

With CAE Analysis Method for Rotary Friction Welding of the Dissimilar Metal Pipes by Closed Forging Method, We Aim to Get the Construction Conditions in the Early Stage of the Parts Development.

A Study on Vaporizing foil actuator welding (VFAW) for steel-aluminum dissimilar metals joining without hardware

Hyuckmin Kwon･Junyeong Jeong･Changyeol Yoo･Younil Jung (Hyundai Motor)･Taeseon Lee (Incheon National University)

This study investigates the use of Vaporizing Foil Actuator Welding (VFAW) for joining dissimilar metals, specifically targeting the union of steel and aluminum alloys. VFAW is an innovative solid-state welding technique that utilizes the rapid vaporization of a thin metallic foil to produce a high-velocity impact, enabling strong bonds between different materials. The main goal is to examine the microstructural and mechanical properties of the joints formed between steel and aluminum, which pose challenges for traditional welding methods due to their differing thermal properties and the propensity to form brittle intermetallic compounds. The results highlight the potential of VFAW to produce high-quality dissimilar metal joints, offering valuable insights for its application in the automotive industries where steel-aluminum hybrids are increasingly desirable for their combined strength and lightweight properties.