Death from caustic ingestion:A case report

Rationale:Acute caustic ingestion from suicidal intent is not usual in emergency departments in developed countries.One of the substances commonly ingested by suicidal patients,phosphoric acid,tends to cause multi-system derangements.Patient’s Concern:A 41-year-old male patient presented with complaints of throat discomfort,severe generalized abdominal pain,and multiple episodes of hematemesis after ingesting a restroom cleaning solution.Diagnosis:Poisoning by acute caustic ingestion(containing<30%phosphoric acid and<4%ethylene glycol).Interventions:The patient was administered 50 mL of 8.4%sodium bicarbonate solution followed by an isotonic sodium bicarbonate solution running at 500 mL/h,a hyperkalemia kit,ceftriaxone,metronidazole,omeprazole,and atropine.The patient then underwent urgent hemodialysis.Outcomes:The patient suffered gastrointestinal bleeding as a result of local caustic injury.In addition,his course of illness was complicated by severe acidemia from high anion gap metabolic acidosis and deranged electrolytes(hyperphosphatemia,hyperkalemia,and hypocalcemia).He developed multi-organ failure and eventually demised.Lessons:The clinician needs to be mindful of the multi-system complications arising from such a caustic ingestion.These patients need to be monitored closely for deterioration,and have prompt management of the various arising complications,to reduce the high morbidity and mortality associated with this condition.

Predicting full-thickness necrosis in adult acute corrosive ingestion injuries in a sub-Saharan African setting

BACKGROUND Corrosive ingestion remains an important global pathology with high morbidity and mortality.Data on the acute management of adult corrosive injuries from sub-Saharan Africa is scarce,with international investigative algorithms,relying heavily on computed tomography(CT),having limited availability in this setting.AIM To investigate the corrosive injury spectrum in a low-resource setting and the applicability of parameters for predicting full-thickness(FT)necrosis and mortality.METHODS A retrospective analysis of a prospective corrosive injury registry(March 1,2017–October 31,2023)was performed to include all adult patients with acute corrosive ingestion managed at a single,academic referral centre in Cape Town,South Africa.Patient demographics,corrosive ingestion details,initial investigations,management,and short-term outcomes were described using descriptive statistics while multivariate analysis with receiver operator characteristic area under the curve graphs(ROC AUC)were used to identify factors predictive of FT necrosis and 30-day mortality.RESULTS One-hundred patients were included,with a mean age of 32 years(SD:11.2 years)and a male predominance(65.0%).The majority(73.0%)were intentional suicide attempts.Endoscopy on admission was the most frequent initial investigation performed(95 patients),while only 17 were assessed with CT.Seventeen patients had full thickness necrosis at surgery,of which eleven underwent emergency resection and six were palliated.Thirty-day morbidity and mortality were 27.0%and 14.0%,respectively.Patients with full thickness necrosis and those with an established perforation had a 30-day mortality of 58.8%and 91.0%,respectively.Full thickness necrosis was associated with a cumulative 2-year survival of only 17.6%.Multivariate analyses with ROC AUC showed admission endoscopy findings,CT findings,and blood gas findings(pH,base excess,lactate),to all have significant predictive value for full thickness necrosis,with endoscopy proving to have the best predictive value(AUC 0.850).CT and endoscopy findings were the only factors predictive of early mortality,with CT performing better than endoscopy(AUC 0.798 vs 0.759).CONCLUSION Intentional corrosive injuries result in devastating morbidity and mortality.Locally,early endoscopy remains the mainstay of severity assessment,but referral for CT imaging should be considered especially when blood gas findings are abnormal.

Accidental Ingestion of Nitric Acid in an Agricultural Company: A Case Study and Literature Review

Introduction: Though common in society, caustic accidental ingestion is rare in the agricultural industry. This study describes a case of ingestion of nitric acid used as an agricultural fertilizer by an ordinary worker at the Société de Cultures Légumières. Clinical Case: This is a 33-year-old unschooled woman who ingested a sip of nitric acid from an abandoned labelled acid canister near a farming plot of land. She showed a burn of the oral cavity with a bleeding tablecloth and an intense retrosternal pain. The duodenal oesophagus fibroscopy screening that was carried out 18 hours after the accident, revealed an esophagitis class 2b. The tests revealed no anomalies. Fifteen (15) days after the accident, the FOGD was normal. Following an 8-month-follow up, no signs of stenosis or degeneration were noted. Conclusion: The accidental ingestion of nitric acid is rare in adult. Its treatment is mainly symptomatic and aims at preserving vital functions without directly fighting the ingested substance off. The right actions must be integrated into the 15-minute Health and Safety awarenesssessions for optimum pre-hospital management. The hospital evaluation is mandatory and is carried out thanks to the digestive endoscopy, which is still relevant in this indication, but is completed by the thoraco-abdominal CT. The latter is very sensitive the transmural necrosis diagnosis.

Endoscopic Aspects of Caustic Injuries of the Upper Gastrointestinal Tract in Parakou, Benin Republic: A Multicenter Study

Objective: Caustic ingestion is a medico-surgical emergency. The objective of this study is to describe endoscopic lesions of the upper gastrointestinal tract secondary to caustic ingestion in Parakou, Benin Republic. Patients and Methods: This was a retrospective and descriptive cross-sectional study. The study was multicenter in the gastrointestinal endoscopy units of the Teaching Hospital Center of Borgou-Alibori and the Military Teaching Hospital of Parakou. It covered the period from July 2015 to October 2021. This included any patient who ingested a caustic substance and performed a gastroscopy in one of the two endoscopy units. The variables studied were: socio-demographic data, the nature of the caustic substance ingested, the time between the caustic ingestion and the performance of gastroscopy and injuries of the upper gastrointestinal tract. Results: Out of the 24 patients included, 19 were men, i.e. a sex ratio of 3.8. Their average age was 25.54 ± 12.04 years with extremes of 6 and 50 years. Five subjects (20.83%) were under the age of 18 and the ingestion was accidental in them. Among the 19 patients aged at least 18 years, caustic ingestion was voluntary in 14 (73.68%). The caustic substance ingested was either a base (sodium hydroxide or caustic soda) or an acid (sulfuric acid) in 14 cases (58.33%) and 10 cases (41.67%), respectively. The time between the caustic ingestion and the performance of gastroscopy varied from 1 to 1095 days. The endoscopic lesions objectified were: stenosis (37.5%), ulcerations (29.17%), necrosis (20.83%), or erythema (12.25%). Conclusion: In Parakou, caustic ingestion, usually bases, is often voluntary in adult men. Endoscopic lesions were often ulcerative but sometimes necrotic.

Changing trends in the minimally invasive surgery for corrosive esophagogastric stricture

Esophagogastric stricture is the troublesome long-term complication of corrosive ingestion with a significant adverse impact on the quality of life.Surgery remains the mainstay of therapy in patients where endoscopic treatment is not feasible or fails to dilate the stricture.Conventional surgical management of esophageal stricture is open esophageal bypass using gastric or colon conduit.Colon is the commonly used esophageal substitute,particularly in those with high pharyngoesophageal strictures and in patients with accompanying gastric strictures.Traditionally colon bypass is performed using an open technique that requires a long midline incision from the xiphisternum to the suprapubic area,with adverse cosmetic outcomes and long-term complications like an incisional hernia.As most of the affected patients are in the second or third decade of life minimally invasive approach is an attractive proposition.However,minimally invasive surgery for corrosive esophagogastric stricture is slow to evolve due to the complex nature of the surgical procedure.With advancements in laparoscopic skills and instrumentation,the feasibility and safety of minimally invasive surgery in corrosive esophagogastric stricture have been documented.Initial series have mainly used a laparoscopic-assisted approach,whereas more recent studies have shown the safety of a total laparoscopic approach.The changing trend from laparoscopic assisted procedure to a totally minimally invasive technique for corrosive esophagogastric stricture should be carefully disseminated to preclude adverse longterm outcomes.Also,well-designed trials with long-term follow-ups are required to document the superiority of minimally invasive surgery for corrosive esophagogastric stricture.The present review focuses on the challenges and changing trends in the minimally invasive treatment of corrosive esophagogastric stricture.

Accidental ingestion of foreign bodies/harmful materials in children from Bahrain:A retrospective cohort study

BACKGROUND Children like to discover their environment by putting substances in their mouths.This behavior puts them at risk of accidentally ingesting foreign bodies(FBs)or harmful materials,which can cause serious morbidities.AIM To study the clinical characteristics,diagnosis,complications,management,and outcomes of accidental ingestion of FBs,caustics,and medications in children.METHODS We conducted a retrospective cohort study of all children admitted for accidental ingestion to the Department of Pediatrics,Salmaniya Medical Complex,Bahrain,between 2011 and 2021.Demographic data,type of FB/harmful material ingested,and investigations used for diagnosis and management were recorded.The patients were divided into three groups based on the type of ingested material(FBs,caustics,and medications).The three groups were compared based on patient demographics,socioeconomic status(SES),symptoms,ingestion scenario,endoscopic and surgical complications,management,and outcomes.The FB anatomical location was categorized as the esophagus,stomach,and bowel and compared with respect to symptoms.The Fisher’s exact,Pearson’s χ^(2),Mann-Whitney U,and Kruskal-Wallis tests were used for comparison.RESULTS A total of 161 accidental ingestion episodes were documented in 153 children.Most children were boys(n=85,55.6%),with a median age of 2.8(interquartile range:1.8-4.4)years.Most participants ingested FBs(n=108,70.6%),31(20.3%)ingested caustics,and the remaining 14(9.2%)ingested medications.Patients with caustic ingestion were younger at the time of presentation(P<0.001)and were more symptomatic(n=26/31,89.7%)than those who ingested medications(n=8/14,57.1%)or FBs(n=52/108,48.6%)(P<0.001).The caustic group had more vomiting(P<0.001)and coughing(P=0.029)than the other groups.Most FB ingestions were asymptomatic(n=55/108,51.4%).In terms of FB location,most esophageal FBs were symptomatic(n=14/16,87.5%),whereas most gastric(n=34/56,60.7%)and intestinal FBs(n=19/32,59.4%)were asymptomatic(P=0.002).Battery ingestion was the most common(n=49,32%).Unsafe toys were the main source of batteries(n=22/43,51.2%).Most episodes occurred while playing(n=49/131,37.4%)or when they were unwitnessed(n=78,57.4%).FBs were ingested more while playing(P<0.001),caustic ingestion was mainly due to unsafe storage(P<0.001),and medication ingestion was mostly due to a missing object(P<0.001).Girls ingested more jewelry items than boys(P=0.006).The stomach was the common location of FB lodgment,both radiologically(n=54/123,43.9%)and endoscopically(n=31/91,34%).Of 107/108(99.1%)patients with FB ingestion,spontaneous passage was noted in 54(35.5%),endoscopic removal in 46(30.3%),laparotomy in 5(3.3%)after magnet ingestion,and direct laryngoscopy in 2(1.3%).Pharmacological therapy was required for 105(70.9%)patients;79/105(75.2%)in the FB group,22/29(75.9%)in the caustic group,and 4/14(28.8%)in the medication group(P=0.001).Omeprazole was the commonly used(n=58;37.9%)and was used more in the caustic group(n=19/28,67.9%)than in the other groups(P=0.001).Endoscopic and surgical complications were detected in 39/148(26.4%)patients.The caustic group had more complications than the other groups(P=0.036).Gastrointestinal perforation developed in the FB group only(n=5,3.4%)and was more with magnet ingestion(n=4)than with other FBs(P<0.001).In patients with FB ingestion,patients aged<1 year(P=0.042),those with middle or low SES(P=0.028),and those with more symptoms at presentation(P=0.027)had more complications.Patients with complications had longer hospital stays(P<0.001)than those without.CONCLUSION Accidental ingestion in children is a serious condition.Symptomatic infants from middle or low SES families have the highest morbidity.Prevention through parental education and government legislation is crucial.

Experimental study on dynamic fracture behavior of three-point bending beam with double deformity inclusions

The dynamic fracture behavior of the three-point bending beam with double deformity inclusions under impact loading is studied by using digital high-speed photography in combination with the transmission-type dynamic caustic method. The experimental results indicate that the fluctuation of crack propagation velocity v first increases and then decreases in the crack propagation process. During the process of crack propagating into the inclusion area, the fracture resistance effect of the circular inclusion is the most significant and the effects of triangular and square inclusions are less obvious. The stress intensity factor near the crack tip increases during the propagation process and reaches its maximum value when the crack tip is close to the inclusions. The crack tip’s dynamic stress intensity factor （ DSIF） decreases when the crack exceeds the middle area of the double inclusions. These results provide an experimental basis and scientific foundation to strengthen the evaluation and fracture analysis of the structure containing deformity inclusions.

Dynamic caustics experimental study on interaction between propagating crack and deformity inclusions in primary structure

The approach combining the dynamic caustics method with high-speed photography technology is used to study the interaction between propagating cracks and three kinds of deformity inclusions（ cylinder inclusion, quadruple inclusion and triangular inclusion） under lowvelocity impact loading. By recording the caustic spots of crack tips at different moments during the crack propagation, the variation regulations of dynamic stress intensity factors（ DSIF） and crack growth velocity with respect to time are obtained. The experimental results showthat the resistance effects to crack growth are varied with different shapes of inclusions in specimens, and the quadruple inclusion＇s effect is more apparent. The distortion degree of caustic spots is affected by the shapes of inclusions as well, and the situation is more serious for cylinder and quadruple inclusions. The overall values of DSIFs of triangular inclusion specimen are greater than the others, and the crack growth velocities, characteristic sizes and DSIFs showprocesses of fluctuations because of the disturbance of reflection waves in specimens. The results provide an experimental basis for the analysis of strength and impact-resistance ability in structures with deformity inclusions.

Caustics study of the effect of glass fibres on dynamic fracture of hardened cement paste

The reflected optical caustics method is applied to study dynamic fracture problems in hardened cement paste. First both the unreinforced cement paste and the glass fibres reinforced cement paste specimens were fabricated and the reflective coating on the surface of the specimen was prepared. Secondly the crack path and the shadow spot patterns during the crack propagation process for the two specimens were recorded by using a multi-spark high speed camera.Thirdly some dynamic parameters of two cement paste specimens including crack onset time the dynamic stress intensity factor and crack growth velocity were determined and analyzed comparatively.This indicates that the glass fibres can improve the fracture resistance and delay fracture time.These results will play an important role in evaluating the dynamic fracture properties of cement paste.

Caustic injury of the upper gastrointestinal tract: A comprehensive review

Prevention has a paramount role in reducing the incidence of corrosive ingestion especially in children, yet this goal is far from being reached in developing countries, where such injuries are largely unreported and their true prevalence simply cannot be extrapolated from random articles or personal experience. The specific pathophysiologic mechanisms are becoming better understood and may have a role in the future management and prevention of long-term consequences, such as esophageal strictures. Whereas the mainstay of diagnosis is considered upper gastrointestinal endoscopy, computed tomography and ultrasound are gaining a more significant role, especially in addressing the need for emergency surgery, whose morbidity and mortality remains high even in the best hands. The need to perform emergency surgery has a persistent long-term negative impact both on survival and functional outcome. Medical or endoscopic prevention of stricture is debatable, yet esophageal stents, absorbable or not, show promising data. Dilatation is the first therapeutic option for strictures and bougies should be considered especially for long, multiple and tortuous narrowing. It is crucial to avoid malnutrition, especially in developingcountries where management strategies are influenced by malnutrition and poor clinical conditions. Late reconstructive surgery, mainly using colon transposition, offers the best results in referral centers, either in children or adults, but such a difficult surgical procedure is often unavailable in developing countries. Possible late development of esophageal cancer, though probably overemphasized, entails careful and long-term endoscopic screening.

Predictability of outcome of caustic ingestion by esophagogastroduodenoscopy in children

AIM: To assess the necessity of esophagogastroduodenoscopy (EGD) to predict the outcome of caustic ingestion in children. METHODS: The study included 206 children who underwent EGD because of ingestion of caustic substances between January 2005 and August 2010. Retrospective analysis of data of the patients was performed. RESULTS: The male/female ratio was 1.6 and mean age was 38.1 ± 28.8 mo. The caustic substances were acidic in 72 (34.9%) cases, alkaline in 56 (27.2%), liquid household bleach in 62 (30.1%), and unknown in 16 (7.8%). Fifty-seven (27.7%) patients were symptom-free. Significant clinical findings were observed in 149 (72.3%) patients. Upper gastrointestinal endoscopy findings of esophageal injury were grade 0 in 86 (41.7%) patients, grade 1 in 49 (23.8%), grade 2a in 42 (20.4%), grade 2b in 28 (13.6%), and grade 3a in 1 (0.5%) patient. 35 patients with grade 2a, 2b, and 3a injuries underwent esophageal dilation at second week of ingestion. Esophageal stricture, which necessitated a regular dilation program developed in 13 of the aforementioned 35 patients. There is no statistically significant difference in the rate of development of esophageal stricture between the patients who ingested acidic (15.3%) and alkaline (8.9%) substances (P = 0.32). Severe gastric injury was detected in 38 (18.5%) patients. The rate of development of gastric injury was significantly higher in the acidic group (14%) than in the alkaline group (2.9%) (P = 0.001). Out of 149 patients with clinical findings, 49 (32.9%) patients had no esophageal injury and 117 (78.5%) patients had no gastric lesion. Esophageal and severe gastric injuries were detected in 20 (35.1%) and 8 (14%) of patients with no clinical findings respectively. Pyloric stenosis developed in 6 patients. Pyloric obstruction improved with balloon dilation in 2 patients. Mean hospitalization time were 1.2 ± 0.5 d for grade 0 and 2.3 ± 5 d for grade 1 and 6.3 ± 6.2 d for grade 2a and 15.8 ± 18.6 d for grade 2b. It was significantly longer for patients with grade 2a and 2b injuries (P = 0.000). CONCLUSION: Endoscopy is an effective technique for determining the presence of esophageal and gastric damage and to avoid unnecessary treatment in patients with no or mild injury.

Therapeutic upper gastrointestinal tract endoscopy in Paediatric Gastroenterology

Since the first report of use of endoscopy in children in the 1970 s, there has seen an exponential growthin published experience and innovation in the field. In this review article we focus on modern age therapeutic endoscopy practice, explaining use of traditional as well as new and innovative techniques, for diagnosis and treatment of diseases in the paediatric upper gastrointestinal tract.

Endoscopic management of esophageal stenosis in children:New and traditional treatments

Post-esophageal atresia anastomotic strictures and postcorrosive esophagitis are the most frequent types of cicatricial esophageal stricture. Congenital esophageal stenosis has been reported to be a rare but typical disease in children; other pediatric conditions are peptic, eosinophilic esophagitis and dystrophic recessive epidermolysis bullosa strictures. The conservative treatment of esophageal stenosis and strictures(ES) rather than surgery is a well-known strategy for children. Before planning esophageal dilation, the esophageal morphology should be assessed in detail for its length, aspect, number and level, and different conservative strategies should be chosen accordingly. Endoscopic dilators and techniques that involve different adjuvant treatment strategies have been reported and depend on the stricture's etiology, the availability of different tools and the operator's experience and preferences. Balloon and semirigid dilators are the most frequently used tools. No high-quality studies have reported on the differences in the efficacies and rates of complications associated with these two types of dilators. There is no consensus in the literature regarding the frequency of dilations or the diameter that should be achieved. The use of adjuvant treatments has been reported in cases of recalcitrant stenosis or strictures with evidence of dysphagic symptoms. Corticosteroids(either systemically or locally injected), the local application of mitomycin C, diathermy and laser ES sectioning have been reported. Some authors have suggested that stenting can reduce both the number of dilations and the treatment length. In many cases, this strategy is effective when either metallic or plastic stents are utilized. Treatment complications, such esophageal perforations, can be conservatively managed, considering surgery only in cases with severe pleural cavity involvement. In cases of stricture relapse,even if such relapses occur following the execution of well-conducted conservative strategies, surgical stricture resection and anastomosis or esophageal substitution are the only remaining options.

Reaction kinetics and mechanism of calcium oxide in dilute sodium aluminate solution with oxalate based on lime causticization

The formation kinetics and mechanism of tricalcium aluminate hydrate and calcium oxalate in dilute sodium aluminate solution and sodium oxalate solution were studied respectively based on the lime causticization, and the optimal conditions for removing the oxalate in dilute sodium aluminate solution as well as the mechanism were finally obtained.The formation processes of tricalcium aluminate hydrate and calcium oxalate are mainly controlled by the chemical reaction and the inner diffusion respectively,and the corresponding reaction rate equations as well as the apparent activation energy were calculated. The hydrocalumite with a spatially interleaved structure will form in dilute sodium aluminate solution with sodium oxalate, greatly removing the oxalate impurity by absorption. Calcium oxalate can be converted to tricalcium aluminate hydrate with the increasing reaction time. The oxalate causticization efficiency and the alumina loss rate can be over 90% and below 31% respectively when reacted at 50℃ with a stirring rate of 200 r/min.

Extraction of Zinc from Electric Arc Furnace Dust by Alkaline Leaching Followed by Fusion of the Leaching Residue with Caustic Soda

Extractability of zinc from two types of electric arc furnace (EAF) dusts containing 24.8% and 16.8% of zinc respectively (denoted as Sample A and Sample B) were tested using direct alkaline leaching followed by fusion of the resulting leaching residues with caustic soda. The experimental results show that the extraction of zinc is heavily dependent on the contents of iron in the dusts. The higher iron content, the lower extraction of zinc is obtained. 53% and 38% of zinc can be extracted when both dusts were directly contacted with 5mol·L^-1 NaOH solution for 42h. The remaining zinc left in the leaching residues, which supposed to be present as zinc ferrites, can be further leached when the residues were fused with caustic soda. Quantitative extraction of zinc can be obtained from the leaching residue of Sample A while only 85% from Sample B. The extractability of zinc from dusts wit hvarious contents of iron is compared. The production flowsheet for zinc from the dusts using the process proposed is discussed.

CAUSTIC DECOMPOSITION OF SCHEELITE AND SCHEELITE－WOLFRAMITE CONCENTRATES THROUGH MECHANICAL ACTIVATION

Based on physicochemical study of the reaction between scheelite and NaOH, a new decomposition process for scheelite and scheelitewolframite concentrate, i. e., mechenically activating caustic decomposition has been developed, and it has been successfu

Dynamic caustics test of blast load impact on neighboring different cross-section roadways

Using digital laser dynamic caustics experimental system and conducting simulation experiment researched the influence rule of blasting excavation of a new roadway on neighboring existed different cross-section roadways. The experimental results show that the influence of blast load on adjacent roadway has a good relationship with the cross-section of roadway. The expansion distance of precrack existed in circular, arch-wall, rectangular roadway is respectively 1.76, 1.61 and 0 cm under blast load.At the same time, the direct-blast side of rectangular roadway has more obvious damage compared with circular and arch-wall roadway. It explains that plane reflects more stress wave than arc, so that it exerts more tensile failure in the direct-blast side, which leads to less stress wave diffracting to the precrack in the back-blast side. When the precrack extends, higher value dynamic stress intensity factor in circular roadway works longer than that of arch-wall roadway. Indirectly, it explains that plane's weakening function on stress wave is significantly stronger than arc. Stress wave brings about self-evident influence on the upper and bottom endpoints of the rectangular roadway, and it respectively extends 1.03, 2.06 cm along the line link direction of the center of the blasthole and the upper and bottom endpoints on the right wall.

Dynamic fracture behavior of rock under impact load using the caustics method

We studied the dynamic fracture mechanical behavior of rock under different impact rates. The fracture experiment was a three-point bending beam subjected to different impact loads monitored using the reflected caustics method. The mechanical parameters for fracture of the three-poim bending beam specimen under impact load are analyzed. The mechanism of crack propagation is discussed. Experimental results show that the dynamic stress intensity factor increases before crack initiation. When the dynamic stress intensity factor reaches its maximum value the crack starts to develop. After crack initiation the dynamic stress intensity factor decreases rapidly and oscillates. As the impact rate increases the cracks initiate earlier, the maximum value of crack growth velocity becomes smaller and the values of dynamic stress intensity factor also vary less during crack propagation. The results provide a theoretical basis for the study of rock dynamic fracture.

DETERMINATION OF THE DYNAMIC STRESS INTENSITY FACTORS,K_Ⅰ~d AND K_Ⅱ~d,FOR A MIXED-MODE PROPAGATING CRACK

In this paper,the dynamic propagation problem of a mixed-mode crack was studied by means of the experimental method of caustics.The initial curve and caustic equations were derived un- der the mixed-mode dynamic condition.A multi-point measurement method for determining the dy- namic stress intensity factors,K_Ⅰ~d and K_Ⅱ~d,and the position of the crack tip was developed.Several other methods were adopted to check this method,and showed that it has a good precision.Finally, the dynamic propagating process of a mixed-mode crack in a three-point bending beam specimen was investigated with our method.

INFLUENCE OF LOADING RATE ON DYNAMIC FRACTURE BEHAVIOR OF FIBER-REINFORCED COMPOSITES

The effect of loading rate on the dynamic fracture properties and the failure mechanisms of glass fiber-reinforced composite materials under mode I fracture is studied. Dynamic reflective caustic experiments are carried out for two loading rates. By measuring the characteristic dimensions of the shadow spots during the caustic experiments, the dynamic SIFs are calculated for different loading rates. The experimental results indicate that the dynamic fracture toughness Kid increases remarkably with increasing loading rate, and the crack grows faster under the high-velocity impact. Moreover, by examining the crack growth routes and the fracture surfaces, it is shown that the loading rate also greatly affects the failure mechanisms at micro-scale.