Investigation on Compressive Strength after Impact Damage of Carbon/Epoxy Laminate

2014 ◽  
Vol 627 ◽  
pp. 397-400
Author(s):  
Hyun Bum Park
Keyword(s):  
Compressive Strength ◽  
Composite Structure ◽  
Impact Damage ◽  
Damage Zone ◽  
Test Procedure ◽  
Standard Test ◽  
Small Scale ◽  
Foreign Object Damage ◽  
Residual Compressive Strength ◽  
The Impact

Development of the Korean small scale aircraft (KC-100) has been carried out by KAI (Korea Aerospace Industry Ltd.) for the BASA(Bilateral Aviation Safety Agreement) program with FAA. The KC-100 aircraft adopted the environmental friendly whole composite structure concept due to low fuel consumption owing to its light weight. However the composite structure has a disadvantage. They are very weak against impact damage due to FOD (Foreign Object Damage). This study is to investigate the residual compressive strength of the carbon/epoxy fabric and UD (Unidirectional prepreg tape) laminate due to impact damages. This residual compressive strength test follows fully the ASTM standard test procedure. Experimental investigation results reveal the residual strengths and the damage mode and size of impact damage specimens. Through these tests, it is found that the residual strength of the impact damage specimens is greatly reduced in comparison to the undamaged specimens depending on increase of both the indentation depth and the impact energy. The size and shape of damage zone greatly affects the reduction of the compressive strength.

Investigation on Damage Tolerance of Carbon/Epoxy Laminate for Aircraft Structural Design

2011 ◽  
Vol 488-489 ◽  
pp. 460-463
Author(s):  
Hyun Bum Park ◽  
Chang Duk Kong ◽  
Kyung Sun Lee
Keyword(s):  
Compressive Strength ◽  
Composite Structure ◽  
Structural Design ◽  
Damage Tolerance ◽  
Epoxy Composite ◽  
General Aviation ◽  
Small Scale ◽  
Foreign Object ◽  
Foreign Object Damage ◽  
Impact Damages

In Korea, the KC-100, which is a small scale piston propeller general aviation aircraft, has been developed to establish a domestic certificate infrastructure and system through the BASA(Bilateral Aviation Safety Agreement) program by KAI(Korea Aerospace Industries, Ltd.). This aircraft adopted the whole composite structure concept for an environmental friendly aircraft through low fuel consumption due to structure weight reduction. However the carbon/epoxy composite structure, which is mainly used for this aircraft, is very weak against foreign object damage. Therefore the purpose of the damage tolerance design philosophy is to ensure that the aircraft can operate safely for a period of time with damage present within the airframe. This study is to investigate the residual compressive strength of the carbon/epoxy UD and fabric laminate due to impact damages. Through investigation on compressive strength, design allowable of carbon/epoxy laminate is determined by the experiment to address design criteria of the composite structure.

Impact Damage Research of Sandwich Composite Laminates

2013 ◽  
Vol 710 ◽  
pp. 136-141
Author(s):  
Li Jun Wei ◽  
Fang Lue Huang ◽  
Hong Peng Li
Keyword(s):  
Compressive Strength ◽  
Composite Laminates ◽  
Impact Damage ◽  
Low Velocity Impact ◽  
Sandwich Composite ◽  
Low Velocity ◽  
Compression Process ◽  
Velocity Impact ◽  
Residual Compressive Strength ◽  
Core Materials

Sandwich composite laminates structure is a classic application of composite material on actual aircraft structural. Dealing with low-velocity impact damage and residual compressive strength of sandwich composite laminates, explicit finite element method of ABAQUS/Explicit software was adopted to simulate low-velocity impact and compression process. Impact response and invalidation on compression between sandwich composite laminates with different core materials and regular composite laminates were compared. The simulation results indicated that softer core materials can absorb more impact energy, reduce the structure damage and enhance the residual compressive strength after impact.

Experimental and simulation investigation on BVID and CAI behaviors of CFRP laminates manufactured by RTM technology

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Fang Chen ◽  
Weixing Yao ◽  
Wen Jiang
Keyword(s):  
Compressive Strength ◽  
Impact Damage ◽  
Projection Area ◽  
Element Analysis ◽  
Mechanical Fracture ◽  
Content Type ◽  
Explicit Finite Element ◽  
Compression Load ◽  
Cfrp Laminates ◽  
The Impact

Purpose The purpose of this paper is to synthetically investigate the impact damage responses of carbon fiber reinforced polymer (CFRP) and its influence on the compression mechanical responses of CFRP laminates, including damage distribution, residual compressive strength and fracture morphology. Design/methodology/approach A progressive damage simulation model is developed to analyze the complicated damage responses of CFRP laminates that are manufactured by resin transfer method (RTM) technology. Based on the ABAQUS/explicit finite element analysis solver, a VUMAT code is proposed to descript the composite materials’ damage behaviors under both impact and compression load. Adopting this proposed model, the primary mechanical indicators of four groups’ 5284RTM/U3160 CFRP laminates with different stacking sequences are predicted. Moreover, impact and compression after impact tests are conducted to verify the accuracy of simulation results. Findings Both simulation and experimental results show that the impact damage with low visible detectability can significantly reduce composites’ compressive strength. For all four groups’ composite laminates, the residual strength ratio is around 35% or even lower. The kernel impact damage near the plates’ geometric center promotes the degradation process of local materials and finally leads to the early occurrence of mechanical fracture. In addition, the impact damage projection area is not sensitive to the parameters of stacking sequences, while the residual compression strength is proportional to the number of 0-degree layers within whole laminates. Originality/value This study helps to understand the effect of an impact event on CFRP laminates’ compressive bearing capacity and provides a numerical method in simulating the damage responses under both impact and compression load.

A Study on Low Velocity Impact of Woven Glass/Phenolic Composite Laminates Considering Environmental Effects

2005 ◽  
Vol 297-300 ◽  
pp. 1303-1308 ◽  
Author(s):  
Jae Hoon Kim ◽  
Duck Hoi Kim ◽  
Hu Shik Kim ◽  
Byoung Jun Park
Keyword(s):  
Compressive Strength ◽  
Environmental Effects ◽  
Impact Loading ◽  
Composite Laminates ◽  
Impact Damage ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Internal Damage ◽  
The Impact ◽  
Phenolic Composite

The objectives of this study are to evaluate the internal damage and compressive residual strength of composite laminate by impact loading. To investigate the environmental effects, as-received and accelerated-aged glass/phenolic laminates are used. UT C-Scan is used to determine the impact damage characteristics and CAI tests are carried out to evaluate quantitatively the reduction of compressive strength by impact loading. The damage modes of the woven glass/phenolic laminates are evaluated. In the case of the accelerated-aged laminates, as aging time increases, initial failure energy and residual compressive strength decrease.

Development of a Novel Test Procedure to Investigate the Impact of Strain Gradients on the Fatigue Endurance of Stainless Steel

2017 ◽  
Author(s):  
Mohammed-Rafi Riley ◽  
Catrin M. Davies ◽  
Stephen Garwood
Keyword(s):  
Stainless Steel ◽  
Stress Field ◽  
Low Cycle Fatigue ◽  
Test Procedure ◽  
Stress Gradient ◽  
Small Scale ◽  
Design Criteria ◽  
Thermal Transients ◽  
The Impact ◽  
Fatigue Endurance

In recent years, there has been an increasing need for component specific testing in nuclear power plant (NPP) materials. This has arisen from changes in fatigue design criteria outlined within the ASME Boiler Pressure and Vessel and Pipe Code (BPVC). These are primarily derived from low-cycle fatigue (LCF) testing on idealized small-scale specimens. For the case of stainless steel (SS), testing is performed under membrane loading on traditional uniaxial round-bar specimens according to standards such as ASTM E606. Here, failure is defined as a 25% drop in load, that typically corresponds to a 3 mm deep crack. Real NPP components however, rarely experience such membrane loading due to their complex geometry and in-service loading (combined primary and secondary stresses). For the case of an internally-pressurized pipe subjected to thermal transients, due to temperature fluctuations in the coolant, an additional through-wall stress field gradient is present. This results in fatigue crack initiation and propagation occurring into a decreasing stress field, which may be expected to result in longer fatigue lives than within small specimen testing and, hence, a large degree of inherent over-conservatism may exist in the ASME design data. This paper describes the development of a novel test procedure able to incorporate the effect of a stress gradient within fatigue endurance testing. A bespoke eight-point bend (8PB) setup has been developed that is capable of performing load-, displacement- and strain-controlled LCF tests. A series of trials have been conducted in all three control modes with the material response validated against finite element analysis (FEA). It is anticipated that this testing procedure can provide a better representation of NPP components under fatigue loading conditions, providing results that would be used to remove over-conservatism within the current design criteria.

Foreign Object Damage Behavior of a SiC Fibrous Ceramic Composite

2017 ◽  
Author(s):  
Nesredin Kedir ◽  
D. Calvin Faucett ◽  
Luis Sanchez ◽  
Sung R. Choi
Keyword(s):  
Ceramic Composite ◽  
Impact Force ◽  
Impact Damage ◽  
Incidence Angle ◽  
Fibrous Composite ◽  
Normal Incidence ◽  
Foreign Object ◽  
Foreign Object Damage ◽  
Post Impact ◽  
The Impact

The response of a SiC fibrous ceramic composite to foreign object damage was determined at ambient temperature and velocities ranging from 40 to 150 m/s. Target specimens were impacted, at a normal incidence angle and in a partially supported configuration, using 1.59 mm-diameter hardened steel ball projectiles. Qualitative analysis of the damage morphologies of targets and projectiles were made via scanning electron microscopy (SEM). In addition, the extent of impact damage was characterized by determining the post-impact strength of each target specimen as a function of impact velocity. Relative to the as-received strength, the fibrous composite showed limited strength degradation due to impact with the maximum reduction of 17 % occurring at 150 m/s. A quasi-static analysis of the impact force prediction was also made based on the principle of energy conservation and the results were verified via experimental data.

Study on the Residual Compressive Strength of a Composite Sandwich Panel with Foam Core after Low Velocity Impact

2012 ◽  
Vol 430-432 ◽  
pp. 484-487 ◽  
Author(s):  
Zong Hong Xie ◽  
Jiang Tian ◽  
Jian Zhao ◽  
Wei Li
Keyword(s):  
Compressive Strength ◽  
Failure Criterion ◽  
Sandwich Panel ◽  
Low Velocity Impact ◽  
Foam Core ◽  
Low Velocity ◽  
Velocity Impact ◽  
Residual Compressive Strength ◽  
Composite Sandwich ◽  
The Impact

The residual compressive strength of a foam core sandwich panel after low-velocity impact was studied by using experimental and analytical methods. The test specimens were compressed uniaxially after they were subjected to a low-velocity-impact. From the observation in the test, one can conclude that the subsequent core crushing around the impact region is the major failure mode in the sandwich structure. A failure criterion named Damage Propagation Criterion was proposed to predict the residual compressive load bearing capability of the low-velocity impacted composite sandwich panel. The characteristic value used in this failure criterion can be calculated by an analytical model developed or by conducting the Sandwich Compression after Impact test.

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