Fracture Resistance of Zirconia Abutments with or without a Titanium Base: An In Vitro Study for Tapered Conical Connection Implants

Dental implants with tapered conical connections are often combined with zirconia abutments for esthetics; however, the effect of the titanium base on the implant components remains unclear. This study evaluated the effects of a titanium base on the fracture resistance of zirconia abutments and damage to the tapered conical connection implants. Zirconia (Z) and titanium base zirconia (ZT) abutments were fastened to Nobel Biocare (NB) implants and Straumann (ST) implants and subjected to static load testing according to ISO 14801:2016. The experiments were performed with 3 mm of the platform exposed (P3) and no platform exposed (P0). The fracture loads were statistically greater in the titanium base abutments than the zirconia abutments for the NB and ST specimens in the P0 condition. In the P3 condition of the ST specimens, the deformation volume of the ZT group was significantly greater than the Z group. The titanium base increased the fracture resistance of the zirconia abutments. Additionally, the titanium base caused more deformation in the P3 condition. The implant joint design may also affect the amount of damage to the implants when under a load. The mechanical properties of the abutment should be considered when selecting a clinical design.

Designing a test rig for structural static-load testing of small horizontal axis wind turbine rotor blades

This paper presents a design of a test rig for structural static load testing of small horizontal wind turbine blades. It is a next step after the success of the DeVie project, a join-research project to boost the wind energy knowhow between Germany and Vietnam. According to the IEC-61400-23 standard for full scale structural testing of rotor blades, and based on existing facilities of HCMUT, especially the aerospace engineering lab. and the engineering mechanics lab., we propose a prototype of a test-rig for structural static load testing of rotor blades. A rotor blade of 4 meters in length, manufactured by China, is used in the case study of our structural static-load test-rig. This paper used the reverse engineering method to determine the blade geometry and performance, since the blade was provided and not designed from scratch. Detailed steps to determine the test load for the rig are the most important, based on the blade design and the wind condition of Vietnam, a study case was set to start the process. Since that required a lot of experience and know-how, beside the work and research from our university, other critically important information was kindly provided by the German's experts in the field. Result of the blade tip displacement are wildly used in this industry to validate the blade design. Our test rig result in 0.289 meters were compared to the reverse engineering and simulation result of 0.28 meter with QBlade/FAST in the same blade loading shown well similarity, this result validated our work process. Future revision of the test rig is promised to provide more function such as fatigue test mode, higher load capacity, faster testing time as well as more accurate result, aiding the domestic market of composite wind turbine blade manufacturing which is still in its infancy.

Bi-Directional Static Load Tests of Pile Models

This work examined a new method of bi-directional static load testing for piles, referencing the Osterberg test. Measurements were taken, on a laboratory scale, using six models of piles driven into a box filled with sand. This method allowed for separate measurements of pile base and pile shaft bearing capacities. Based on the results, the total pile bearing capacity and equivalent Q–s diagrams were estimated. The results obtained show that the structure of the equivalent curve according to Osterberg is a good approximation of the standard Q–s curve obtained from load tests, except for loads close to the limit of bearing capacity (those estimates are also complicated by the inapplicability and ambiguity of a definition of the notion of limit bearing capacity); the equivalent pile capacity in the Osterberg method represents, on average, about 80% of the capacity from standard tests.