Mg and its alloys have been comprehensively studied and show huge potential for clinical orthopedic applications. However, balancing the mechanical strength and corrosion resistance of alloys is still a challenge. In light of this, micro-level contents of Zn and Ca were added to pure Mg to fabricate a Mg−2Zn−0.05Ca microalloy to expectedly enhance the mechanical strength and concurrently improve the corrosion resistance. The characteristics of the rolled Mg−2Zn−0.05Ca microalloy were explored using optical microscopy, X-ray diffraction, and tensile tests. The corrosion behavior and mechanical strength loss were explored using electrochemical and immersion tests. The effects of the microalloy extract on the proliferation, adhesion, and osteogenic differentiation of MC3T3-E1 cells were systematically studied. Moreover, implantations were done in femoral condyles of rabbits to study the degradation properties, osteogenic effect, mechanical strength loss, and biosafety of the microalloy. The ultimate tensile strength and yield strength of the rolled microalloy were found to be significantly elevated to 257 ± 2.74 and 237.6 ± 8.29 MPa, respectively. The microalloy showed a stable and gradual strength loss during degradation, both in vivo and in vitro. Concurrently, the microalloy exhibited improved corrosion resistance ability and especially, in vivo, the rolled microalloy exhibited a comparable degradation rate to that of rolled pure Mg within the initial 12 weeks of implantation. Additionally, the microalloy promoted osteogenesis, both in vitro and in vivo, and no short-and long-term toxicities of the microalloy were observed in rabbits. This study suggested that the rolled Mg−2Zn−0.05Ca microalloy effectively balanced the mechanical strength and corrosion resistance and showed potential application as bone implants.

This study aimed to evaluate the safety and efficacy of the special WE43 magnesium alloy stretch plates (SPs) used as fixation device for anterior cruciate ligament (ACL) reconstruction in a beagle model. Eleven beagle dogs underwent ACL reconstruction using WE43 SPs to fix the ligament grafts with the femoral ends, whereas titanium interferences were employed in the tibia ends. Load-to-failure tests were conducted to evaluate the mechanical properties. A comprehensive set of histological observations was performed to observe the local tissue response and assess the status of the attachment between the bone tissue and ligament grafts. Microcomputed tomography and scanning electron microscopy in conjunction with energy spectrum analysis were conducted to evaluate the degradation rate in vivo and investigate the morphology of the cross-section of the SPs and the element distribution in vivo. Immersion tests were employed to investigate the corrosion properties in vitro. The special WE43 SPs showed not only good mechanical strength but also a suitable degradation rate in vivo. The results indicated the special WE43 SP could be considered as a novel fixation device for ACL reconstruction.

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With the weight-reduction requirement for transportation tools, more and more carbon fiber reinforced plastics (CFRPs) will be applied. It is known that the plastics will have a brittle fracture under impact loads, and therefore, their resistance capability on impact damage is a crucial factor which restricts the application of CFRPs. The present paper studies the impact damage and residual stiffness of the CFRPs through experiments. The identical specimens were impacted repeatedly by pendulum with a specified constant energy, and then, their residual bending stiffness and strength were measured by three-point-bending tests. Finally, the relationship between the residual stiffness and impact numbers were established. The results will be used in damage-based stiffness predition for CFRPs material and structures.

With the weight-reduction requirement for transportation tools, more and more plastics and composite materials will be applied. However, the connection between plastics, polymer-based composite and traditional metal, such as steel or aluminum, possibly become the weakest region and thus decrease the structural safety, therefore, its mechanical properties should be investigated. In this paper, a typical single-lap joint was analyzed experimentally and numerically under the three-point-bending loads, and the results were compared and finite element model was updated. Based on the validated simulation technology, three other joints were simulated and all joints were compared, and suggestion for design of composite joints was provided.