Study on the Creep Properties of Resin Concrete

2014 ◽  
Vol 472 ◽  
pp. 649-653
Author(s):  
Hui Cun Shen ◽  
Kui Tian ◽  
Yan Hua Hu
Keyword(s):  
Dynamic Stiffness ◽  
Structure Design ◽  
Test Method ◽  
Bending Test ◽  
Creep Properties ◽  
Four Point Bending ◽  
Long Term Effect ◽  
Urgent Task ◽  
Machined Parts ◽  
New Material

Resin concrete is a new material which can be made into machine bed instead of the traditional pieces of gray cast iron as the machine base, it can improve the dynamic stiffness of machine tools and the quality of machined parts, and extend the campaign life, reduce noise and improve efficiency. However, due to the long-term effect of load of the resin concrete, the elastic deformation occurs in its component, and the strain will increase over time. Thus it can affect the resin concretes service life, and the calculation of creep has become an urgent task in structure design and use, which should be taken seriously. In this paper, the bending creep properties of resin concrete beam were studied and analyzed by using four-point bending test method. The creep curve under different load levels were obtained, and the viscoelastic properties were analyzed.

scholarly journals Investigation of Interlaminar Defects and their Influence on Interlaminar Strength

1996 ◽  
Vol 5 (4) ◽  
pp. 096369359600500
Author(s):  
J Ziao ◽  
J Tao
Keyword(s):  
Tensile Strength ◽  
Large Scale ◽  
Peel Strength ◽  
Test Method ◽  
Bending Test ◽  
Four Point Bending ◽  
Transverse Tensile ◽  
Interlaminar Shear ◽  
Transverse Tensile Strength ◽  
Set Up

In this paper, we directed our attention to the interlaminar defects and their influence on the interlaminar strengths. With the aid of a S-570 scanning electron microscope, the morphology and distribution of interlaminar defects were inspected and documented. According to their shape, size and cause of formation, the defects were classified into five types: flakiness void, irregular shaped debond, local imperfectly cured resin, debond in two multi-directional plies, and inhomogeneous fibers and the large scale debond by these fibers. The cause of defects formation was discussed by analyzing the manufacturing process of composites. The influence of defects on the interlaminar strength and its mechanism was analyzed experimentally and theoretically. The results indicate that these defects, with different effects, decrease the interlaminar strength because they form interlaminar cracks, and the interlaminar shear strength is less affected than interlaminar tensile strength, which is measured according to GB4944 test method. To comprehend defects distribution effect, a four-point-bending test method was introduced to measure the interlaminar peel strength, and a discussion was made on the correlation between the interlaminar tensile strength, interlaminar peel strength and in-plane transverse tensile strength. Finally the concept of interlaminar defect coefficient, which can be used to characterize the defects, was set up and the formula to calculate it was proposed.

Influence of Aspect Ratio of Macro Synthetic Fiber on Mechanical Properties of Shotcrete

2013 ◽  
Vol 652-654 ◽  
pp. 1226-1232
Author(s):  
An Shuang Su ◽  
Yue Bo Cai
Keyword(s):  
Flexural Strength ◽  
Moisture Content ◽  
Steel Fiber ◽  
Loading Rate ◽  
Polypropylene Fiber ◽  
Test Method ◽  
Bending Test ◽  
Synthetic Fiber ◽  
Flexural Toughness ◽  
Four Point Bending

Influences of moisture content and loading rate on flexural toughness were experimentally studied for fiber reinforced shotcrete (FRSC) with steel fiber or macro synthetic polypropylene fiber. According to the four-point bending test method specified in ASTM C1609 and Chinese standard CECS 13, the flexural toughness of specimens after drying for 0h, 16h, 24h and 72h in condition of (20±2)°C and (60±5)% relative humidity was tested at a loading rate of 0.05 mm/min. For specimens after drying for 24h and 72h, flexural toughness was tested at loading rates of 0.05 mm/min, 0.10 mm/min, and 0.20 mm/min respectively. With the moisture content decreasing, the flexural toughness T100,2.0, first-peak flexural strength, and residual flexural strength at prescribed deflections of FRSC exhibited decreasing tendency. The specimens with 0.5 vol% of steel fiber showed higher T100,2.0 value than that with 0.9 vol% of macro synthetic fiber. The residual strength and flexural toughness of FRSC increased with the increase of loading rate.

Increase of bending strength and maximum deflection of concrete reinforced with CFRP strips

2011 ◽  
Vol 18 (1-2) ◽  
pp. 93-97
Author(s):  
Goichi Ben ◽  
Kazuhiro Sakata ◽  
Kazuma Saito
Keyword(s):  
High Performance ◽  
Bending Strength ◽  
Concrete Beams ◽  
Beam Theory ◽  
Design Criterion ◽  
Test Method ◽  
Bending Test ◽  
Plastic Behavior ◽  
Four Point Bending ◽  
Miyagi Prefecture

AbstractIn 1981, many detached houses collapsed owing to the earthquake which took place at the coast of Miyagi Prefecture in Japan, because ferroconcrete was not used as the base of most of the collapsed houses. Therefore, the earthquake-proof design criterion was revised and it was obliged to use ferroconcrete as the base of detached houses ever since. However, there are still more than 10 million detached houses using aged concrete as the base in Japan. In this paper, a reinforcement method for the aged concrete is demonstrated by using the high performance carbon fiber reinforced plastic (CFRP) strips. Three kinds of concrete beams reinforced with the CFRP strips with different vertical insert positions and different numbers of the CFRP strips were tested by a four point bending test method. In order to clarify the effects of CFRP strips, a concrete beam without reinforcement was also tested. The results of the experiment showed that the maximum deflections of the concrete beams reinforced with the CFRP strip were more than 100 times larger than those of the concrete beams without reinforcement. Although the concrete beams without the CFRP strips collapsed instantly, the concrete beams reinforced with the CFRP strips gradually failed, which were similar to the plastic behavior of metals. This result means that the residents can afford to escape safely from the houses in the event of possible earthquakes. The experimental results were compared with the analytical ones obtained from the composite beam theory and the failure criterion. Both results showed good agreement and the effectiveness of base concrete reinforced with CFRP strips was demonstrated.

Evaluation of the Remaining Prestress Force and Center Negative Bending Moment in Crossties Removed From Track After 25 Years of Service

2019 ◽  
Author(s):  
James D. Scott ◽  
Robert J. Peterman ◽  
Aaron A. Robertson ◽  
B. Terry Beck ◽  
Kyle A. Riding
Keyword(s):  
Bending Moment ◽  
Test Method ◽  
Bending Test ◽  
Direct Tension ◽  
Longitudinal Splitting ◽  
Prestressing Steel ◽  
Prestressing Force ◽  
Four Point Bending ◽  
Negative Bending

Extensive research is currently being conducted by the team to understand the prestressing steel and concrete properties that cause high bonding stresses and lead to longitudinal splitting cracks, and how to mitigate this failure in future designs. One parameter of interest that affects the bonding stress is the amount of prestressing force in a crosstie. To help quantify the amount of prestress force necessary to provide a durable long-term crosstie, a study on existing crossties that have performed well in track for over 25 years was conducted to evaluate the center negative bending moment, and determine the remaining prestress force for each tie. The remaining prestress force in each tie was determined using a new proposed method in which ties are loaded in direct tension. The new test method was also conducted on new ties instrumented with vibrating wire strain gages to verify the method. The testing results reveal that a majority of the existing ties evaluated have a remaining prestress force in the range of 84–95 kips. These forces are significantly lower than the remaining prestress force after losses of newer tie designs. This can be seen when comparing the tension test results of the existing ties with the results of the new ties. Ties were loaded upside-down in four-point bending to determine their center negative cracking moments. The test setup and procedure used closely resembles the center negative bending moment test outlined in AREMA 30, with minor variations. For each different tie design in the study, the center negative design moment was calculated following the AREMA 30 procedure, and compared to the experimental cracking moments. Of the seven different existing tie designs investigated, four would meet the requirements of the current AREMA 30 center negative bending test.

Comparison of a standardized four-point bending test to an implant system test of an osteosynthetic system under static and dynamic load condition

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Christian Halbauer ◽  
Hendrik Schorler ◽  
Laura Liberto ◽  
Felix Capanni
Keyword(s):  
Load Condition ◽  
Bending Moment ◽  
Secondary Phase ◽  
Mechanical Analysis ◽  
Test Method ◽  
Bone Plate ◽  
Bending Test ◽  
Four Point Bending ◽  
Four Point Bending Test ◽  
Implant System

Abstract Current test standards of osteosynthetic implants examine the bone plate and screw separately leading to unrealistic load scenarios and unknown performance of the system as a whole, which prevents the identification of characteristic failures in clinical use. A standardized static and dynamic four-point bending test (ASTM F382) was performed on a bone plate. Based on that standard, an advanced implant system test (IST) was designed and performed to test a mechanical construct consisting of a bone plate, screws and an artificial bone substitute out of Polyoxymethylene (POM). The test object was an osteosynthetic system to treat fractured ulna bones. Both results of the conventional and advanced test method were analyzed and compared to one another. The static results show a similar yield point (YP) relative to the bending moment with just 9% difference. Dynamic results show a bi-phasic behavior of the displacement vs. cycle data for the IST. The secondary phase can be defined as a constantly increasing plastic deflection or ratcheting effect quantified by its slope in mm per one million cycles, leading to a 10 times higher slope for the IST than the conventional test. The IST has a high impact on the test results and the resultant interpretation of the mechanical behavior of the osteosynthetic system. A constantly increasing plastic deflection might lead to fatigue failures and to a loss of the mechanical durability. The development of new standardizations referring to the whole system within reasonable boundary conditions of individual biomechanical applications is crucial for high quality mechanical analysis.

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